Nano-Micro Letters

Rational Design of Cost-Effective Metal-Doped ZrO2 for Oxygen Evolution Reaction

Yuefeng Zhang, Tianyi Wang, Liang Mei, Ruijie Yang, Weiwei Guo, Hao Li — Thu, 25 Apr 2024 00:00:00 +0000

The design of cost-effective electrocatalysts is an open challenging for oxygen evolution reaction (OER) due to the “stable-or-active” dilemma. Zirconium dioxide (ZrO₂), a versatile and low-cost material that can be stable under OER operating conditions, exhibits inherently poor OER activity from experimental observations. Herein, we doped a series of metal elements to regulate the ZrO₂ catalytic activity in OER via spin-polarized density functional theory calculations with van der Waals interactions. Microkinetic modeling as a function of the OER activity descriptor (G_O*-G_HO*) displays that 16 metal dopants enable to enhance OER activities over a thermodynamically stable ZrO₂ surface, among which Fe and Rh (in the form of single-atom dopant) reach the volcano peak (i.e. the optimal activity of OER under the potential of interest), indicating excellent OER performance. Free energy diagram calculations, density of states, and ab initio molecular dynamics simulations further showed that Fe and Rh are the effective dopants for ZrO₂, leading to low OER overpotential, high conductivity, and good stability. Considering cost-effectiveness, single-atom Fe doped ZrO₂ emerged as the most promising catalyst for OER. This finding offers a valuable perspective and reference for experimental researchers to design cost-effective catalysts for the industrial-scale OER production.

Highlights:
1 Surface energy and surface Pourbaix diagram reveal that ZrO₂ (111) is the most thermodynamically stable facet and is preferentially occupied by HO* at the equilibrium potential of oxygen evolution reaction (OER).
2 Microkinetic modeling analyzed the OER activity of 40 single-metal doped ZrO₂ and identified 16 metals exhibit improved catalytic activity, with Rh and Fe dopants showing the remarkable improvement.
3 Thermodynamic free energy diagrams, density of states analysis, and ab initio molecular dynamics simulations further confirm that Fe–ZrO₂ and Rh–ZrO₂ are highly promising catalysts for OER, showcasing low ΔG for the rate-determining step, high conductivity, and exceptional stability.

Structurally Flexible 2D Spacer for Suppressing the Electron–Phonon Coupling Induced Non-Radiative Decay in Perovskite Solar Cells

Wed, 24 Apr 2024 00:00:00 +0000

This study presents experimental evidence of the dependence of non-radiative recombination processes on the electron–phonon coupling of perovskite in perovskite solar cells (PSCs). Via A-site cation engineering, a weaker electron–phonon coupling in perovskite has been achieved by introducing the structurally soft cyclohexane methylamine (CMA⁺) cation, which could serve as a damper to alleviate the mechanical stress caused by lattice oscillations, compared to the rigid phenethyl methylamine (PEA⁺) analog. It demonstrates a significantly lower non-radiative recombination rate, even though the two types of bulky cations have similar chemical passivation effects on perovskite, which might be explained by the suppressed carrier capture process and improved lattice geometry relaxation. The resulting PSCs achieve an exceptional power conversion efficiency (PCE) of 25.5% with a record-high open-circuit voltage (V_OC) of 1.20 V for narrow bandgap perovskite (FAPbI₃). The established correlations between electron–phonon coupling and non-radiative decay provide design and screening criteria for more effective passivators for highly efficient PSCs approaching the Shockley–Queisser limit.

Highlights:
1 The soft 2D material reduces the coupling strength between carriers and longitudinal optical phonons, releasing the mechanical stress of lattice vibration.
2 The power conversion efficiency of rigid devices and flexible devices reaches 25.5% and 23.4%, respectively.

Rational Design of Ruddlesden–Popper Perovskite Ferrites as Air Electrode for Highly Active and Durable Reversible Protonic Ceramic Cells

Na Yu, Idris Temitope Bello, Xi Chen, Tong Liu, Zheng Li, Yufei Song, Meng Ni — Mon, 22 Apr 2024 00:00:00 +0000

Reversible protonic ceramic cells (RePCCs) hold promise for efficient energy storage, but their practicality is hindered by a lack of high-performance air electrode materials. Ruddlesden–Popper perovskite Sr₃Fe₂O_7−δ (SF) exhibits superior proton uptake and rapid ionic conduction, boosting activity. However, excessive proton uptake during RePCC operation degrades SF’s crystal structure, impacting durability. This study introduces a novel A/B-sites co-substitution strategy for modifying air electrodes, incorporating Sr-deficiency and Nb-substitution to create Sr_2.8Fe_1.8Nb_0.2O_7−δ (D-SFN). Nb stabilizes SF's crystal, curbing excessive phase formation, and Sr-deficiency boosts oxygen vacancy concentration, optimizing oxygen transport. The D-SFN electrode demonstrates outstanding activity and durability, achieving a peak power density of 596 mW cm⁻² in fuel cell mode and a current density of − 1.19 A cm⁻² in electrolysis mode at 1.3 V, 650 °C, with excellent cycling durability. This approach holds the potential for advancing robust and efficient air electrodes in RePCCs for renewable energy storage.

Highlights:
1 A novel A/B-sites co-substitution strategy was introduced to enhance the performance and durability of Ruddlesden–Popper perovskite Sr₃Fe₂O₇−δ (SF)-based air electrodes for reversible protonic ceramic cells (RePCCs).
2 Simultaneous Sr-deficiency and Nb-substitution in SF result in Sr_2.8Fe_1.8Nb_0.2O₇−δ (D-SFN), offering improved structural stability under RePCC conditions by suppressing the formation of Sr₃Fe₂(OH)₁₂ phase.
3 The introduction of Sr-deficiency enhances oxygen vacancy concentration in D-SFN, promoting efficient oxygen transport within the material and contributing to excellent activity in RePCCs.

Achieving Ultra-Broad Microwave Absorption Bandwidth Around Millimeter-Wave Atmospheric Window Through an Intentional Manipulation on Multi-Magnetic Resonance Behavior

Mon, 22 Apr 2024 00:00:00 +0000

The utilization of electromagnetic waves is rapidly advancing into the millimeter-wave frequency range, posing increasingly severe challenges in terms of electromagnetic pollution prevention and radar stealth. However, existing millimeter-wave absorbers are still inadequate in addressing these issues due to their monotonous magnetic resonance pattern. In this work, rare-earth La³⁺ and non-magnetic Zr⁴⁺ ions are simultaneously incorporated into M-type barium ferrite (BaM) to intentionally manipulate the multi-magnetic resonance behavior. By leveraging the contrary impact of La³⁺ and Zr⁴⁺ ions on magnetocrystalline anisotropy field, the restrictive relationship between intensity and frequency of the multi-magnetic resonance is successfully eliminated. The magnetic resonance peak-differentiating and imitating results confirm that significant multi-magnetic resonance phenomenon emerges around 35 GHz due to the reinforced exchange coupling effect between Fe³⁺ and Fe²⁺ ions. Additionally, Mössbauer spectra analysis, first-principle calculations, and least square fitting collectively identify that additional La³⁺ doping leads to a profound rearrangement of Zr⁴⁺ occupation and thus makes the portion of polarization/conduction loss increase gradually. As a consequence, the La³⁺–Zr⁴⁺ co-doped BaM achieves an ultra-broad bandwidth of 12.5 + GHz covering from 27.5 to 40 + GHz, which holds remarkable potential for millimeter-wave absorbers around the atmospheric window of 35 GHz.

Highlights:
1 The frequency and intensity of multi-magnetic resonance are freely regulated by co-doping La³⁺ and Zr⁴⁺ ions.
2 Zr⁴⁺ occupation is elaborately modified for promoting the portion of polarization/conduction loss to increase profoundly.
3 The optimized electromagnetic characteristics lead to an ultra-wide bandwidth of 12.5+ GHz around millimeter-wave atmospheric window.

Accelerating Oxygen Electrocatalysis Kinetics on Metal–Organic Frameworks via Bond Length Optimization

Fri, 19 Apr 2024 00:00:00 +0000

Metal–organic frameworks (MOFs) have been developed as an ideal platform for exploration of the relationship between intrinsic structure and catalytic activity, but the limited catalytic activity and stability has hampered their practical use in water splitting. Herein, we develop a bond length adjustment strategy for optimizing naphthalene-based MOFs that synthesized by acid etching Co-naphthalenedicarboxylic acid-based MOFs (donated as AE-CoNDA) to serve as efficient catalyst for water splitting. AE-CoNDA exhibits a low overpotential of 260 mV to reach 10 mA cm⁻² and a small Tafel slope of 62 mV dec⁻¹ with excellent stability over 100 h. After integrated AE-CoNDA onto BiVO₄, photocurrent density of 4.3 mA cm⁻² is achieved at 1.23 V. Experimental investigations demonstrate that the stretched Co–O bond length was found to optimize the orbitals hybridization of Co 3d and O 2p, which accounts for the fast kinetics and high activity. Theoretical calculations reveal that the stretched Co–O bond length strengthens the adsorption of oxygen-contained intermediates at the Co active sites for highly efficient water splitting.

Highlights:
1 The acid etching Co-naphthalenedicarboxylic acid-based metal–organic frameworks (donated as AE-CoNDA) catalyst displayed an excellent oxygen evolution reaction (OER) activity for long-term stability.
2 Integration of the AE-CoNDA cocatalyst into BiVO₄ achieved a remarkable PEC-OER activity.
3 The stretched Co-O bond length regulated the spin state transition at the Co active sites.
4 The optimized high spin state of Co sites adjusted the orbitals hybridization of Co 3d and O 2p.

Structural Engineering of Hierarchical Magnetic/Carbon Nanocomposites via In Situ Growth for High-Efficient Electromagnetic Wave Absorption

Xianyuan Liu, Jinman Zhou, Ying Xue, Xianyong Lu — Mon, 15 Apr 2024 00:00:00 +0000

Materials exhibiting high-performance electromagnetic wave absorption have garnered considerable scientific and technological attention, yet encounter significant challenges. Developing new materials and innovative structural design concepts is crucial for expanding the application field of electromagnetic wave absorption. Particularly, hierarchical structure engineering has emerged as a promising approach to enhance the physical and chemical properties of materials, providing immense potential for creating versatile electromagnetic wave absorption materials. Herein, an exceptional multi-dimensional hierarchical structure was meticulously devised, unleashing the full microwave attenuation capabilities through in situ growth, self-reduction, and multi-heterogeneous interface integration. The hierarchical structure features a three-dimensional carbon framework, where magnetic nanoparticles grow in situ on the carbon skeleton, creating a necklace-like structure. Furthermore, magnetic nanosheets assemble within this framework. Enhanced impedance matching was achieved by precisely adjusting component proportions, and intelligent integration of diverse interfaces bolstered dielectric polarization. The obtain Fe₃O₄-Fe nanoparticles/carbon nanofibers/Al-Fe₃O₄-Fe nanosheets composites demonstrated outstanding performance with a minimum reflection loss (RL_min) value of − 59.3 dB and an effective absorption bandwidth (RL ≤ − 10 dB) extending up to 5.6 GHz at 2.2 mm. These notable accomplishments offer fresh insights into the precision design of high-efficient electromagnetic wave absorption materials.

Highlights:
1 Hierarchical Fe₃O₄-Fe@CNFs/Al-Fe₃O₄-Fe nanocomposites were constructed by in situ growth, vacuum-assisted filtration, and self-reduction methods.
2 The carbon framework, with in situ grown magnetic nanoparticles, supports two-dimensional magnetic nanosheets, achieving excellent electromagnetic performance and good impedance matching.
3 Excellent reflection loss value (− 59.3 dB), broadband wave absorption (5.6 GHz at 2.2 mm thickness), and low radar cross-section value were achieved.

In Situ Atomic Reconstruction Engineering Modulating Graphene-Like MXene-Based Multifunctional Electromagnetic Devices Covering Multi-Spectrum

Mon, 15 Apr 2024 00:00:00 +0000

With the diversified development of big data, detection and precision guidance technologies, electromagnetic (EM) functional materials and devices serving multiple spectrums have become a hot topic. Exploring the multispectral response of materials is a challenging and meaningful scientific question. In this study, MXene/TiO₂ hybrids with tunable conduction loss and polarization relaxation are fabricated by in situ atomic reconstruction engineering. More importantly, MXene/TiO₂ hybrids exhibit adjustable spectral responses in the GHz, infrared and visible spectrums, and several EM devices are constructed based on this. An antenna array provides excellent EM energy harvesting in multiple microwave bands, with |S₁₁| up to − 63.2 dB, and can be tuned by the degree of bending. An ultra-wideband bandpass filter realizes a passband of about 5.4 GHz and effectively suppresses the transmission of EM signals in the stopband. An infrared stealth device has an emissivity of less than 0.2 in the infrared spectrum at wavelengths of 6–14 µm. This work can provide new inspiration for the design and development of multifunctional, multi-spectrum EM devices.

Highlights:
1 MXene/TiO₂ hybrids are prepared by a simple calcination treatment, and their electromagnetic response is customized by in situ atomic reconstruction engineering.
2 Based on the excellent electromagnetic response of MXene/TiO₂ hybrids, a series of electromagnetic devices are constructed.
3 Multi-spectrum stealth is realized covering visible-light, infrared radiation and GHz.

Multifunctional MOF@COF Nanoparticles Mediated Perovskite Films Management Toward Sustainable Perovskite Solar Cells

Thu, 11 Apr 2024 00:00:00 +0000

Although covalent organic frameworks (COFs) with high π-conjugation have recently exhibited great prospects in perovskite solar cells (PSCs), their further application in PSCs is still hindered by face-to-face stacking and aggregation issues. Herein, metal–organic framework (MOF-808) is selected as an ideal platform for the in situ homogeneous growth of a COF to construct a core–shell MOF@COF nanoparticle, which could effectively inhibit COF stacking and aggregation. The synergistic intrinsic mechanisms induced by the MOF@COF nanoparticles for reinforcing intrinsic stability and mitigating lead leakage in PSCs have been explored. The complementary utilization of π-conjugated skeletons and nanopores could optimize the crystallization of large-grained perovskite films and eliminate defects. The resulting PSCs achieve an impressive power conversion efficiency of 23.61% with superior open circuit voltage (1.20 V) and maintained approximately 90% of the original power conversion efficiency after 2000 h (30–50% RH and 25–30 °C). Benefiting from the synergistic effects of the in situ chemical fixation and adsorption abilities of the MOF@COF nanoparticles, the amount of lead leakage from unpackaged PSCs soaked in water (< 5 ppm) satisfies the laboratory assessment required for the Resource Conservation and Recovery Act Regulation.

Highlights:
1 Covalent organic frameworks (COFs) were in situ homogeneously growing on the surface of metal–organic framework (MOF-808) by a covalent bond to construct a core–shell MOF@COF nanoparticle.
2 MOF@COF optimized the crystallinity of perovskite to achieve 23.61% efficiency with superior open circuit voltage (1.20 V).
3 MOF-assisted COFs to ‘trap’ leaked lead ions by in situ chemical fixation and adsorption.
4 The amount of lead leakage (<5 ppm) satisfied the laboratory assessment.

Compliant Iontronic Triboelectric Gels with Phase-Locked Structure Enabled by Competitive Hydrogen Bonding

Tue, 09 Apr 2024 00:00:00 +0000

Rapid advancements in flexible electronics technology propel soft tactile sensing devices toward high-level biointegration, even attaining tactile perception capabilities surpassing human skin. However, the inherent mechanical mismatch resulting from deficient biomimetic mechanical properties of sensing materials poses a challenge to the application of wearable tactile sensing devices in human–machine interaction. Inspired by the innate biphasic structure of human subcutaneous tissue, this study discloses a skin-compliant wearable iontronic triboelectric gel via phase separation induced by competitive hydrogen bonding. Solvent-nonsolvent interactions are used to construct competitive hydrogen bonding systems to trigger phase separation, and the resulting soft-hard alternating phase-locked structure confers the iontronic triboelectric gel with Young's modulus (6.8–281.9 kPa) and high tensile properties (880%) compatible with human skin. The abundance of reactive hydroxyl groups gives the gel excellent tribopositive and self-adhesive properties (peel strength > 70 N m⁻¹). The self-powered tactile sensing skin based on this gel maintains favorable interface and mechanical stability with the working object, which greatly ensures the high fidelity and reliability of soft tactile sensing signals. This strategy, enabling skin-compliant design and broad dynamic tunability of the mechanical properties of sensing materials, presents a universal platform for broad applications from soft robots to wearable electronics.

Highlights:
1 A bionic phase-locked structure-inspired iontronic triboelectric gel is proposed with good mechanical compliance for wearable haptic sensing applications.
2 Competitive hydrogen bonding systems are constructed through polymer-solvent-nonsolvent interactions, and regeneration of polymers with weak hydrogen bond donors triggers controlled phase separation.
3 Self-powered haptic skin constructed with iontronic triboelectric gel has a modulus (150.6 kPa) and stretchability (> 400%) similar to that of the human body, enabling fidelity transmission of haptic signals and precise recognition of sensing objects.

Hollow Metal–Organic Framework/MXene/Nanocellulose Composite Films for Giga/Terahertz Electromagnetic Shielding and Photothermal Conversion

Tian Mai, Lei Chen, Pei‑Lin Wang, Qi Liu, Ming‑Guo Ma — Mon, 08 Apr 2024 00:00:00 +0000

With the continuous advancement of communication technology, the escalating demand for electromagnetic shielding interference (EMI) materials with multifunctional and wideband EMI performance has become urgent. Controlling the electrical and magnetic components and designing the EMI material structure have attracted extensive interest, but remain a huge challenge. Herein, we reported the alternating electromagnetic structure composite films composed of hollow metal–organic frameworks/layered MXene/nanocellulose (HMN) by alternating vacuum-assisted filtration process. The HMN composite films exhibit excellent EMI shielding effectiveness performance in the GHz frequency (66.8 dB at Ka-band) and THz frequency (114.6 dB at 0.1–4.0 THz). Besides, the HMN composite films also exhibit a high reflection loss of 39.7 dB at 0.7 THz with an effective absorption bandwidth up to 2.1 THz. Moreover, HMN composite films show remarkable photothermal conversion performance, which can reach 104.6 °C under 2.0 Sun and 235.4 °C under 0.8 W cm⁻², respectively. The unique micro- and macro-structural design structures will absorb more incident electromagnetic waves via interfacial polarization/multiple scattering and produce more heat energy via the local surface plasmon resonance effect. These features make the HMN composite film a promising candidate for advanced EMI devices for future 6G communication and the protection of electronic equipment in cold environments.

Highlights:
1 The composite films are composed of hollow metal–organic frameworks/layered MXene/nanocellulose with unique alternating electromagnetic structures.
2 The optimized composite films exhibit excellent EMI shielding performance of 66.8 dB at GHz frequency and 114.6 dB at THz frequency.
3 The EMI shielding ability of composite films to electromagnetic waves is verified by practical visualized application simulation.
4 The composite films show remarkable photothermal conversion performance, which can reach 235.4 °C under 0.8 W cm⁻².

Interface Engineering of Titanium Nitride Nanotube Composites for Excellent Microwave Absorption at Elevated Temperature

Thu, 04 Apr 2024 00:00:00 +0000

Currently, the microwave absorbers usually suffer dreadful electromagnetic wave absorption (EMWA) performance damping at elevated temperature due to impedance mismatching induced by increased conduction loss. Consequently, the development of high-performance EMWA materials with good impedance matching and strong loss ability in wide temperature spectrum has emerged as a top priority. Herein, due to the high melting point, good electrical conductivity, excellent environmental stability, EM coupling effect, and abundant interfaces of titanium nitride (TiN) nanotubes, they were designed based on the controlling kinetic diffusion procedure and Ostwald ripening process. Benefiting from boosted heterogeneous interfaces between TiN nanotubes and polydimethylsiloxane (PDMS), enhanced polarization loss relaxations were created, which could not only improve the depletion efficiency of EMWA, but also contribute to the optimized impedance matching at elevated temperature. Therefore, the TiN nanotubes/PDMS composite showed excellent EMWA performances at varied temperature (298–573 K), while achieved an effective absorption bandwidth (EAB) value of 3.23 GHz and a minimum reflection loss (RL_min) value of − 44.15 dB at 423 K. This study not only clarifies the relationship between dielectric loss capacity (conduction loss and polarization loss) and temperature, but also breaks new ground for EM absorbers in wide temperature spectrum based on interface engineering.

Highlights:
1 The boosted heterogeneous interfaces in titanium nitride (TiN) nanotube/polydimethylsiloxane (PDMS) composite contributed to strong polarization loss relaxation ability.
2 The TiN nanotubes/PDMS composite possessed both good impedance matching behavior and strong dielectric loss ability in wide temperature spectrum.
3 The TiN nanotubes/PDMS composite exhibited excellent EMWA performances (effective absorption bandwidth value of 3.23 GHz and minimum reflection loss value of − 44.15 dB) at the varied temperature from 298 to 573 K.

Compositional and Hollow Engineering of Silicon Carbide/Carbon Microspheres as High-Performance Microwave Absorbing Materials with Good Environmental Tolerance

Tue, 02 Apr 2024 00:00:00 +0000

Microwave absorbing materials (MAMs) characterized by high absorption efficiency and good environmental tolerance are highly desirable in practical applications. Both silicon carbide and carbon are considered as stable MAMs under some rigorous conditions, while their composites still fail to produce satisfactory microwave absorption performance regardless of the improvements as compared with the individuals. Herein, we have successfully implemented compositional and structural engineering to fabricate hollow SiC/C microspheres with controllable composition. The simultaneous modulation on dielectric properties and impedance matching can be easily achieved as the change in the composition of these composites. The formation of hollow structure not only favors lightweight feature, but also generates considerable contribution to microwave attenuation capacity. With the synergistic effect of composition and structure, the optimized SiC/C composite exhibits excellent performance, whose the strongest reflection loss intensity and broadest effective absorption reach − 60.8 dB and 5.1 GHz, respectively, and its microwave absorption properties are actually superior to those of most SiC/C composites in previous studies. In addition, the stability tests of microwave absorption capacity after exposure to harsh conditions and Radar Cross Section simulation data demonstrate that hollow SiC/C microspheres from compositional and structural optimization have a bright prospect in practical applications.

Highlights:
1 Hollow SiC/C microspheres with controllable composition have been successfully synthesized by simultaneously implementing compositional and structural engineering.
2 The optimum dielectric properties (i.e., conductivity loss and polarization loss) and impedance matching characteristics can achieve outstanding microwave absorption performance.
3 Broadband wave absorption (5.1 GHz with only 1.8 mm thickness), high efficiency loss (− 60.8 dB at 10.4 GHz) combined with good environmental tolerance, demonstrate their bright prospects in practice.

A Fully-Integrated Memristor Chip for Edge Learning

Yanhong Zhang, Liang Chu, Wenjun Li — Tue, 02 Apr 2024 00:00:00 +0000

Highlights:
1 The fully-integrated memristor chip for edge learning provides a solid foundation for neural network computation.
2 The fully-integrated memristor chip enables efficient object recognition in noisy backgrounds while minimizing energy consumption.
3 The computing-in-memory chip represents an innovative and interdisciplinary technology that extends beyond multiple research domains.

Stretchable, Transparent, and Ultra-Broadband Terahertz Shielding Thin Films Based on Wrinkled MXene Architectures

Tue, 02 Apr 2024 00:00:00 +0000

With the increasing demand for terahertz (THz) technology in security inspection, medical imaging, and flexible electronics, there is a significant need for stretchable and transparent THz electromagnetic interference (EMI) shielding materials. Existing EMI shielding materials, like opaque metals and carbon-based films, face challenges in achieving both high transparency and high shielding efficiency (SE). Here, a wrinkled structure strategy was proposed to construct ultra-thin, stretchable, and transparent terahertz shielding MXene films, which possesses both isotropous wrinkles (height about 50 nm) and periodic wrinkles (height about 500 nm). Compared to flat film, the wrinkled MXene film (8 nm) demonstrates a remarkable 36.5% increase in SE within the THz band. The wrinkled MXene film exhibits an EMI SE of 21.1 dB at the thickness of 100 nm, and an average EMI SE/t of 700 dB μm⁻¹ over the 0.1–10 THz. Theoretical calculations suggest that the wrinkled structure enhances the film's conductivity and surface plasmon resonances, resulting in an improved THz wave absorption. Additionally, the wrinkled structure enhances the MXene films' stretchability and stability. After bending and stretching (at 30% strain) cycles, the average THz transmittance of the wrinkled film is only 0.5% and 2.4%, respectively. The outstanding performances of the wrinkled MXene film make it a promising THz electromagnetic shielding materials for future smart windows and wearable electronics.

Highlights:
1 A stretchable, transparent, and ultra-broadband (0.1–10 THz) terahertz shielding MXene (Ti₃C₂T_x) film has been fabricated by a structure engineering strategy.
2 Theoretical calculations indicate that the wrinkled structure enhances the film's conductivity and surface plasmon resonances, resulting in an improved THz wave absorption.
3 The wrinkled MXene films exhibit superb conformability to surfaces with random curvatures, and can be used as a shielding film for THz imaging.

Amphipathic Phenylalanine-Induced Nucleophilic–Hydrophobic Interface Toward Highly Reversible Zn Anode

Thu, 28 Mar 2024 00:00:00 +0000

Aqueous Zn²⁺-ion batteries (AZIBs), recognized for their high security, reliability, and cost efficiency, have garnered considerable attention. However, the prevalent issues of dendrite growth and parasitic reactions at the Zn electrode interface significantly impede their practical application. In this study, we introduced a ubiquitous biomolecule of phenylalanine (Phe) into the electrolyte as a multifunctional additive to improve the reversibility of the Zn anode. Leveraging its exceptional nucleophilic characteristics, Phe molecules tend to coordinate with Zn²⁺ ions for optimizing the solvation environment. Simultaneously, the distinctive lipophilicity of aromatic amino acids empowers Phe with a higher adsorption energy, enabling the construction of a multifunctional protective interphase. The hydrophobic benzene ring ligands act as cleaners for repelling H₂O molecules, while the hydrophilic hydroxyl and carboxyl groups attract Zn²⁺ ions for homogenizing Zn²⁺ flux. Moreover, the preferential reduction of Phe molecules prior to H₂O facilitates the in situ formation of an organic–inorganic hybrid solid electrolyte interphase, enhancing the interfacial stability of the Zn anode. Consequently, Zn||Zn cells display improved reversibility, achieving an extended cycle life of 5250 h. Additionally, Zn||LMO full cells exhibit enhanced cyclability of retaining 77.3% capacity after 300 cycles, demonstrating substantial potential in advancing the commercialization of AZIBs.

Highlights:
1 The amphipathic phenylalanine-adsorbed layer contributes to form a nucleophilic–hydrophobic interface that homogenizes Zn²⁺ flux while repelling H₂O molecules from contacting Zn anode.
2 The preferential reduction of phenylalanine (Phe) prior to H₂O facilitates in situ formation of an organic–inorganic hybrid solid electrolyte interphase, enhancing the interfacial stability.
3 Benefiting from the triple protection of Phe, the Zn||Zn and Zn||LMO cells display significantly improved electrochemical performances, even at extreme diluted electrolytes.

Dilute Aqueous-Aprotic Electrolyte Towards Robust Zn-Ion Hybrid Supercapacitor with High Operation Voltage and Long Lifespan

Mon, 25 Mar 2024 00:00:00 +0000

With the merits of the high energy density of batteries and power density of supercapacitors, the aqueous Zn-ion hybrid supercapacitors emerge as a promising candidate for applications where both rapid energy delivery and moderate energy storage are required. However, the narrow electrochemical window of aqueous electrolytes induces severe side reactions on the Zn metal anode and shortens its lifespan. It also limits the operation voltage and energy density of the Zn-ion hybrid supercapacitors. Using ‘water in salt’ electrolytes can effectively broaden their electrochemical windows, but this is at the expense of high cost, low ionic conductivity, and narrow temperature compatibility, compromising the electrochemical performance of the Zn-ion hybrid supercapacitors. Thus, designing a new electrolyte to balance these factors towards high-performance Zn-ion hybrid supercapacitors is urgent and necessary. We developed a dilute water/acetonitrile electrolyte (0.5 m Zn(CF₃SO₃)₂ + 1 m LiTFSI-H₂O/AN) for Zn-ion hybrid supercapacitors, which simultaneously exhibited expanded electrochemical window, decent ionic conductivity, and broad temperature compatibility. In this electrolyte, the hydration shells and hydrogen bonds are significantly modulated by the acetonitrile and TFSI⁻ anions. As a result, a Zn-ion hybrid supercapacitor with such an electrolyte demonstrates a high operating voltage up to 2.2 V and long lifespan beyond 120,000 cycles.

Highlights:
1 A novel aqueous/aprotic electrolyte with low salt concentration (i.e., 0.5 m Zn(CF₃SO₃)₂+1 m LiTFSI) demonstrated an expanded electrochemical window, which can simultaneously stabilize Zn metal anode and increase the operation voltage of Zn-ion hybrid supercapacitors.
2 The coordination shell of the electrolyte induced by acetonitrile and LiTFSI can not only suppress the Zn corrosion and hydrogen evolution reaction but also promote the cathodic stability and ion migration, which is depicted by the density functional theory simulations together with experimental characterizations.
3 The Zn-ion hybrid supercapacitor based on the developed electrolyte can operate within 0–2.2 V in a wide temperature range with an ultra-long lifespan (> 120,000 cycles).

Boosting Hydrogen Storage Performance of MgH2 by Oxygen Vacancy-Rich H-V2O5 Nanosheet as an Excited H-Pump

Li Ren, Yinghui Li, Zi Li, Xi Lin, Chong Lu, Wenjiang Ding, Jianxin Zou — Thu, 21 Mar 2024 00:00:00 +0000

MgH₂ is a promising high-capacity solid-state hydrogen storage material, while its application is greatly hindered by the high desorption temperature and sluggish kinetics. Herein, intertwined 2D oxygen vacancy-rich V₂O₅ nanosheets (H-V₂O₅) are specifically designed and used as catalysts to improve the hydrogen storage properties of MgH₂. The as-prepared MgH₂-H-V₂O₅ composites exhibit low desorption temperatures (T_onset = 185 °C) with a hydrogen capacity of 6.54 wt%, fast kinetics (E_a = 84.55 ± 1.37 kJ mol⁻¹ H₂ for desorption), and long cycling stability. Impressively, hydrogen absorption can be achieved at a temperature as low as 30 °C with a capacity of 2.38 wt% within 60 min. Moreover, the composites maintain a capacity retention rate of ~ 99% after 100 cycles at 275 °C. Experimental studies and theoretical calculations demonstrate that the in-situ formed VH₂/V catalysts, unique 2D structure of H-V₂O₅ nanosheets, and abundant oxygen vacancies positively contribute to the improved hydrogen sorption properties. Notably, the existence of oxygen vacancies plays a double role, which could not only directly accelerate the hydrogen ab/de-sorption rate of MgH₂, but also indirectly affect the activity of the catalytic phase VH₂/V, thereby further boosting the hydrogen storage performance of MgH₂. This work highlights an oxygen vacancy excited “hydrogen pump” effect of VH₂/V on the hydrogen sorption of Mg/MgH₂. The strategy developed here may pave a new way toward the development of oxygen vacancy-rich transition metal oxides catalyzed hydride systems.

Highlights:
1 Graphene-like 2D V₂O₅ nanosheets rich in oxygen vacancies are designed as multi-functional catalysts to fabricate MgH₂-H-V₂O₅ composites.
2 Hydrogen release starts from 185 °C and capacity retention is as high as 99% after 100 cycles at 275 °C.
3 The composites present rapid kinetics and impressive hydrogen absorption capability at near room temperature.
4 The oxygen vacancies could directly enhance kinetics of MgH₂ while indirectly exciting “hydrogen pump” effect of VH₂/V.

Wettability Gradient-Induced Diode: MXene-Engineered Membrane for Passive-Evaporative Cooling

Leqi Lei, Shuo Meng, Yifan Si, Shuo Shi, Hanbai Wu, Jieqiong Yang, Jinlian Hu — Thu, 21 Mar 2024 00:00:00 +0000

Thermoregulatory textiles, leveraging high-emissivity structural materials, have arisen as a promising candidate for personal cooling management; however, their advancement has been hindered by the underperformed water moisture transportation capacity, which impacts on their thermophysiological comfort. Herein, we designed a wettability-gradient-induced-diode (WGID) membrane achieving by MXene-engineered electrospun technology, which could facilitate heat dissipation and moisture-wicking transportation. As a result, the obtained WGID membrane could obtain a cooling temperature of 1.5 °C in the “dry” state, and 7.1 °C in the “wet” state, which was ascribed to its high emissivity of 96.40% in the MIR range, superior thermal conductivity of 0.3349 W m⁻¹ K⁻¹ (based on radiation- and conduction-controlled mechanisms), and unidirectional moisture transportation property. The proposed design offers an approach for meticulously engineering electrospun membranes with enhanced heat dissipation and moisture transportation, thereby paving the way for developing more efficient and comfortable thermoregulatory textiles in a high-humidity microenvironment.

Highlights:
1 Engineering MXene into electrospun nanofibers can effectively enhance its thermal emissivity and conductance, and the unidirectional water transport of the wettability-gradient-induced-diode (WGID) membrane displayed diode-like properties with wettability gradient by tailoring the water contact angle of each single layer.
2 The WGID membrane could achieve a cooling temperature of 1.5 °C in the “dry” state, and 7.1 °C in the “wet” state, with high emissivity of 96.40% in the MIR range, superior thermal conductivity of 0.3349 W m⁻¹ K⁻¹.
3 Zero-energy-consumption for personal cooling management via multiple heat dissipation pathways, including thermal radiation, conduction, and evaporation.

Correction to: Highly Porous Yet Transparent Mechanically Flexible Aerogels Realizing Solar–Thermal Regulatory Cooling

Thu, 21 Mar 2024 00:00:00 +0000

The demand for highly porous yet transparent aerogels with mechanical flexibility and solar-thermal dual-regulation for energy-saving windows is significant but challenging. Herein, a delaminated aerogel film (DAF) is fabricated through filtration-induced delaminated gelation and ambient drying. The delaminated gelation process involves the assembly of fluorinated cellulose nanofiber (FCNF) at the solid–liquid interface between the filter and the filtrate during filtration, resulting in the formation of lamellar FCNF hydrogels with strong intra-plane and weak interlayer hydrogen bonding. By exchanging the solvents from water to hexane, the hydrogen bonding in the FCNF hydrogel is further enhanced, enabling the formation of the DAF with intra-layer mesopores upon ambient drying. The resulting aerogel film is lightweight and ultra-flexible, which possesses desirable properties of high visible-light transmittance (91.0%), low thermal conductivity (33 mW m⁻¹ K⁻¹), and high atmospheric-window emissivity (90.1%). Furthermore, the DAF exhibits reduced surface energy and exceptional hydrophobicity due to the presence of fluorine-containing groups, enhancing its durability and UV resistance. Consequently, the DAF has demonstrated its potential as solar-thermal regulatory cooling window materials capable of simultaneously providing indoor lighting, thermal insulation, and daytime radiative cooling under direct sunlight. Significantly, the enclosed space protected by the DAF exhibits a temperature reduction of 2.6 °C compared to that shielded by conventional architectural glass.

Highlights:
1 A lamellar-structured fluorinated cellulose nanofiber aerogel film is prepared by filtration-induced delaminated gelation and ambient drying.
2 The aerogel film demonstrates exceptional mechanical flexibility and resistance to complex deformations.
3 The aerogel film displays low thermal conductivity, high visible-light transmittance and superior selective infrared emissivity, rendering it high solar-thermal regulatory cooling performance.

ROS Balance Autoregulating Core–Shell CeO2@ZIF-8/Au Nanoplatform for Wound Repair

Thu, 21 Mar 2024 00:00:00 +0000

Reactive oxygen species (ROS) plays important roles in living organisms. While ROS is a double-edged sword, which can eliminate drug-resistant bacteria, but excessive levels can cause oxidative damage to cells. A core–shell nanozyme, CeO₂@ZIF-8/Au, has been crafted, spontaneously activating both ROS generating and scavenging functions, achieving the multi-faceted functions of eliminating bacteria, reducing inflammation, and promoting wound healing. The Au Nanoparticles (NPs) on the shell exhibit high-efficiency peroxidase-like activity, producing ROS to kill bacteria. Meanwhile, the encapsulation of CeO₂ core within ZIF-8 provides a seal for temporarily limiting the superoxide dismutase and catalase-like activities of CeO₂ nanoparticles. Subsequently, as the ZIF-8 structure decomposes in the acidic microenvironment, the CeO₂ core is gradually released, exerting its ROS scavenging activity to eliminate excess ROS produced by the Au NPs. These two functions automatically and continuously regulate the balance of ROS levels, ultimately achieving the function of killing bacteria, reducing inflammation, and promoting wound healing. Such innovative ROS spontaneous regulators hold immense potential for revolutionizing the field of antibacterial agents and therapies.

Highlights:
1 The innovation of this work mainly lies in the auto-regulation of reactive oxygen species (ROS) balance effective by combination of ROS antibacterial and ROS scavenging anti-inflammatory functions with a core–shell nanoplatform (CeO₂@ZIF-8/Au), which can not only achieve high antibacterial efficiency, but also promote wound healing, and provide a new idea for the nano-catalytic system in the field of wound healing of bacterial infection.

A Skin-Inspired Self-Adaptive System for Temperature Control During Dynamic Wound Healing

Mon, 11 Mar 2024 00:00:00 +0000

The thermoregulating function of skin that is capable of maintaining body temperature within a thermostatic state is critical. However, patients suffering from skin damage are struggling with the surrounding scene and situational awareness. Here, we report an interactive self-regulation electronic system by mimicking the human thermos-reception system. The skin-inspired self-adaptive system is composed of two highly sensitive thermistors (thermal-response composite materials), and a low-power temperature control unit (Laser-induced graphene array). The biomimetic skin can realize self-adjusting in the range of 35–42 °C, which is around physiological temperature. This thermoregulation system also contributed to skin barrier formation and wound healing. Across wound models, the treatment group healed ~ 10% more rapidly compared with the control group, and showed reduced inflammation, thus enhancing skin tissue regeneration. The skin-inspired self-adaptive system holds substantial promise for next-generation robotic and medical devices.

Highlights:
1 An interactive electronic system inspired by the temperature self-regulation of human skin.
2 Heat stimulation therapy and temperature monitoring during dynamic wound healing.
3 Mechanism of temperature self-regulation during dynamic wound healing.

Harness High-Temperature Thermal Energy via Elastic Thermoelectric Aerogels

Mon, 11 Mar 2024 00:00:00 +0000

Despite notable progress in thermoelectric (TE) materials and devices, developing TE aerogels with high-temperature resistance, superior TE performance and excellent elasticity to enable self-powered high-temperature monitoring/warning in industrial and wearable applications remains a great challenge. Herein, a highly elastic, flame-retardant and high-temperature-resistant TE aerogel, made of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/single-walled carbon nanotube (PEDOT:PSS/SWCNT) composites, has been fabricated, displaying attractive compression-induced power factor enhancement. The as-fabricated sensors with the aerogel can achieve accurately pressure stimuli detection and wide temperature range monitoring. Subsequently, a flexible TE generator is assembled, consisting of 25 aerogels connected in series, capable of delivering a maximum output power of 400 μW when subjected to a temperature difference of 300 K. This demonstrates its outstanding high-temperature heat harvesting capability and promising application prospects for real-time temperature monitoring on industrial high-temperature pipelines. Moreover, the designed self-powered wearable sensing glove can realize precise wide-range temperature detection, high-temperature warning and accurate recognition of human hand gestures. The aerogel-based intelligent wearable sensing system developed for firefighters demonstrates the desired self-powered and highly sensitive high-temperature fire warning capability. Benefitting from these desirable properties, the elastic and high-temperature-resistant aerogels present various promising applications including self-powered high-temperature monitoring, industrial overheat warning, waste heat energy recycling and even wearable healthcare.

Highlights:
1 A thermoelectric aerogel of highly elastic, flame-retardant and high-temperature-resistant PEDOT:PSS/SWCNT composite is fabricated.
2 The assembled thermoelectric generator generates a maximum output power of 400 μW at a temperature difference of 300 K.
3 The self-powered wearable sensing glove can achieve wide-range temperature detection, complex hand motion recognition and high-temperature warning.
4 The intelligent fire warning system enables highly sensitive and repeatable monitoring and alarm capabilities for high-temperature fire sources.

Naturally Crosslinked Biocompatible Carbonaceous Liquid Metal Aqueous Ink Printing Wearable Electronics for Multi-Sensing and Energy Harvesting

King Yan Chung, Bingang Xu, Di Tan, Qingjun Yang, Zihua Li, Hong Fu — Mon, 11 Mar 2024 00:00:00 +0000

Achieving flexible electronics with comfort and durability comparable to traditional textiles is one of the ultimate pursuits of smart wearables. Ink printing is desirable for e-textile development using a simple and inexpensive process. However, fabricating high-performance atop textiles with good dispersity, stability, biocompatibility, and wearability for high-resolution, large-scale manufacturing, and practical applications has remained challenging. Here, water-based multi-walled carbon nanotubes (MWCNTs)-decorated liquid metal (LM) inks are proposed with carbonaceous gallium–indium micro-nanostructure. With the assistance of biopolymers, the sodium alginate-encapsulated LM droplets contain high carboxyl groups which non-covalently crosslink with silk sericin-mediated MWCNTs. E-textile can be prepared subsequently via printing technique and natural waterproof triboelectric coating, enabling good flexibility, hydrophilicity, breathability, wearability, biocompatibility, conductivity, stability, and excellent versatility, without any artificial chemicals. The obtained e-textile can be used in various applications with designable patterns and circuits. Multi-sensing applications of recognizing complex human motions, breathing, phonation, and pressure distribution are demonstrated with repeatable and reliable signals. Self-powered and energy-harvesting capabilities are also presented by driving electronic devices and lighting LEDs. As proof of concept, this work provides new opportunities in a scalable and sustainable way to develop novel wearable electronics and smart clothing for future commercial applications.

Highlights:
1 Naturally crosslinked carbonaceous liquid metal aqueous printable ink mediated by biopolymers.
2 E-textile with conductivity, stability, wearability, and aesthetic characteristics.
3 Multi-applications in health monitoring, pressure sensing, and energy harvesting.

Publisher Correction to: Highly Elastic, Bioresorbable Polymeric Materials for Stretchable, Transient Electronic Systems

Wed, 06 Mar 2024 00:00:00 +0000

Substrates or encapsulants in soft and stretchable formats are key components for transient, bioresorbable electronic systems; however, elastomeric polymers with desired mechanical and biochemical properties are very limited compared to non-transient counterparts. Here, we introduce a bioresorbable elastomer, poly(glycolide-co-ε-caprolactone) (PGCL), that contains excellent material properties including high elongation-at-break (< 1300%), resilience and toughness, and tunable dissolution behaviors. Exploitation of PGCLs as polymer matrices, in combination with conducing polymers, yields stretchable, conductive composites for degradable interconnects, sensors, and actuators, which can reliably function under external strains. Integration of device components with wireless modules demonstrates elastic, transient electronic suture system with on-demand drug delivery for rapid recovery of post-surgical wounds in soft, time-dynamic tissues.

Highlights:
1 The paper introduces a bioresorbable elastomer, poly(glycolide-co-ε-caprolactone) (PGCL), with remarkable mechanical properties, including high elongation-at-break (< 1300%), resilience, and toughness (75 MJ m⁻³) for soft and transient electronics.
2 Fabrication of conducting polymers with PGCL yields stretchable, conductive composites for transient electronic devices, functioning reliably under external strains.
3 The study demonstrates the feasibility of a disintegrable electronic suture system with on-demand drug delivery for rapid recovery of post-surgical wounds on soft, time-dynamic tissues or versatile biomedical areas of interest.

Critical Solvation Structures Arrested Active Molecules for Reversible Zn Electrochemistry

Tue, 05 Mar 2024 00:00:00 +0000

Aqueous Zn-ion batteries (AZIBs) have attracted increasing attention in next-generation energy storage systems due to their high safety and economic. Unfortunately, the side reactions, dendrites and hydrogen evolution effects at the zinc anode interface in aqueous electrolytes seriously hinder the application of aqueous zinc-ion batteries. Here, we report a critical solvation strategy to achieve reversible zinc electrochemistry by introducing a small polar molecule acetonitrile to form a “catcher” to arrest active molecules (bound water molecules). The stable solvation structure of [Zn(H₂O)₆]²⁺ is capable of maintaining and completely inhibiting free water molecules. When [Zn(H₂O)₆]²⁺ is partially desolvated in the Helmholtz outer layer, the separated active molecules will be arrested by the “catcher” formed by the strong hydrogen bond N–H bond, ensuring the stable desolvation of Zn²⁺. The Zn||Zn symmetric battery can stably cycle for 2250 h at 1 mAh cm⁻², Zn||V₆O₁₃ full battery achieved a capacity retention rate of 99.2% after 10,000 cycles at 10 A g⁻¹. This paper proposes a novel critical solvation strategy that paves the route for the construction of high-performance AZIBs.

Highlights:
1 Critical solvation structure changes the hydrogen bond network through “catchers”.
2 Catcher further arrests the active molecules to promote Zn²⁺ deposition.
3 The Zn||Zn symmetric battery can stably cycle for 2250 h. Zn||V₆O₁₃ full battery achieved a capacity retention rate of 99.2% after 10,000 cycles.

A Molecular-Sieving Interphase Towards Low-Concentrated Aqueous Sodium-Ion Batteries

Mon, 04 Mar 2024 00:00:00 +0000

Aqueous sodium-ion batteries are known for poor rechargeability because of the competitive water decomposition reactions and the high electrode solubility. Improvements have been reported by salt-concentrated and organic-hybridized electrolyte designs, however, at the expense of cost and safety. Here, we report the prolonged cycling of ASIBs in routine dilute electrolytes by employing artificial electrode coatings consisting of NaX zeolite and NaOH-neutralized perfluorinated sulfonic polymer. The as-formed composite interphase exhibits a molecular-sieving effect jointly played by zeolite channels and size-shrunken ionic domains in the polymer matrix, which enables high rejection of hydrated Na⁺ ions while allowing fast dehydrated Na⁺ permeance. Applying this coating to electrode surfaces expands the electrochemical window of a practically feasible 2 mol kg^–1 sodium trifluoromethanesulfonate aqueous electrolyte to 2.70 V and affords Na₂MnFe(CN)₆//NaTi₂(PO₄)₃ full cells with an unprecedented cycling stability of 94.9% capacity retention after 200 cycles at 1 C. Combined with emerging electrolyte modifications, this molecular-sieving interphase brings amplified benefits in long-term operation of ASIBs.

Highlights:
1 A molecular-sieving electrode coating towards low-concentrated aqueous sodium-ion batteries is constructed by applying a composite of NaX zeolite and NaOH-neutralized Nafion.
2 Resulting from a molecular sieving effect of zeolite channels and size-shrunken ionic domains in Nafion, the as-prepared coating layer reject hydrated Na+ ions and allow fast dehydrated Na⁺ permeance.
3 200 cycles of Na₂MnFe(CN)₆//NaTi₂(PO₄)₃ full cells can be achieved in a practically feasible 2 m aqueous electrolyte.

Kinetic-Thermodynamic Promotion Engineering toward High-Density Hierarchical and Zn-Doping Activity-Enhancing ZnNiO@CF for High-Capacity Desalination

Jie Ma, Siyang Xing, Yabo Wang, Jinhu Yang, Fei Yu — Mon, 04 Mar 2024 00:00:00 +0000

Despite the promising potential of transition metal oxides (TMOs) as capacitive deionization (CDI) electrodes, the actual capacity of TMOs electrodes for sodium storage is significantly lower than the theoretical capacity, posing a major obstacle. Herein, we prepared the kinetically favorable Zn_xNi_{1 − x}O electrode in situ growth on carbon felt (Zn_xNi_{1 − x}O@CF) through constraining the rate of OH⁻ generation in the hydrothermal method. Zn_xNi_{1 − x}O@CF exhibited a high-density hierarchical nanosheet structure with three-dimensional open pores, benefitting the ion transport/electron transfer. And tuning the moderate amount of redox-inert Zn-doping can enhance surface electroactive sites, actual activity of redox-active Ni species, and lower adsorption energy, promoting the adsorption kinetic and thermodynamic of the Zn_0.2Ni_0.8O@CF. Benefitting from the kinetic-thermodynamic facilitation mechanism, Zn_0.2Ni_0.8O@CF achieved ultrahigh desalination capacity (128.9 mg_NaCl g⁻¹), ultra-low energy consumption (0.164 kW h kg_NaCl⁻¹), high salt removal rate (1.21 mg_NaCl g⁻¹ min⁻¹), and good cyclability. The thermodynamic facilitation and Na⁺ intercalation mechanism of Zn_0.2Ni_0.8O@CF are identified by the density functional theory calculations and electrochemical quartz crystal microbalance with dissipation monitoring, respectively. This research provides new insights into controlling electrochemically favorable morphology and demonstrates that Zn-doping, which is redox-inert, is essential for enhancing the electrochemical performance of CDI electrodes.

Highlights:
1 Through facial basicity adjustment, kinetically favorable Zn_xNi_1-xO@CF electrode was formed with a high density hierarchical structure and three dimensional open pores.
2 The optimal Zn-doping ratio in Zn_xNi_1-xO@CF has excellent sodium storage and desalination performance (128.9 mg g^-1).
3 The mechanism of Na⁺ intercalation process was studied by electrochemical quartz crystal microbalance with dissipation monitoring in situ test and the activation mechanism of redox-inert Zn-doping on electrode materials was reported.

MXenes for Bioinspired Soft Actuators: Advancements in Angle-Independent Structural Colors and Beyond

Siavash Iravani, Rajender S. Varma — Mon, 04 Mar 2024 00:00:00 +0000

Soft actuators have garnered substantial attention in current years in view of their potential appliances in diverse domains like robotics, biomedical devices, and biomimetic systems. These actuators mimic the natural movements of living organisms, aiming to attain enhanced flexibility, adaptability, and versatility. On the other hand, angle-independent structural color has been achieved through innovative design strategies and engineering approaches. By carefully controlling the size, shape, and arrangement of nanostructures, researchers have been able to create materials exhibiting consistent colors regardless of the viewing angle. One promising class of materials that holds great potential for bioinspired soft actuators is MXenes in view of their exceptional mechanical, electrical, and optical properties. The integration of MXenes for bioinspired soft actuators with angle-independent structural color offers exciting possibilities. Overcoming material compatibility issues, improving color reproducibility, scalability, durability, power supply efficiency, and cost-effectiveness will play vital roles in advancing these technologies. This perspective appraises the development of bioinspired MXene-centered soft actuators with angle-independent structural color in soft robotics.

Highlights:
1 MXene-based soft actuators with angle-independent structural colors have the potential to contribute to various fields, including display technologies, camouflage systems, sensors, and beyond.
2 Bioinspiration has paved the way for developing advanced structural colored soft actuators for biomimetic soft robots.
3 This perspective appraises the development of bioinspired MXene-based soft actuators with angle-independent structural color and beyond in soft robotics.

Enabling an Inorganic-Rich Interface via Cationic Surfactant for High-Performance Lithium Metal Batteries

Mon, 04 Mar 2024 00:00:00 +0000

An anion-rich electric double layer (EDL) region is favorable for fabricating an inorganic-rich solid–electrolyte interphase (SEI) towards stable lithium metal anode in ester electrolyte. Herein, cetyltrimethylammonium bromide (CTAB), a cationic surfactant, is adopted to draw more anions into EDL by ionic interactions that shield the repelling force on anions during lithium plating. In situ electrochemical surface-enhanced Raman spectroscopy results combined with molecular dynamics simulations validate the enrichment of NO₃⁻/FSI⁻ anions in the EDL region due to the positively charged CTA⁺. In-depth analysis of SEI structure by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry results confirmed the formation of the inorganic-rich SEI, which helps improve the kinetics of Li⁺ transfer, lower the charge transfer activation energy, and homogenize Li deposition. As a result, the Li||Li symmetric cell in the designed electrolyte displays a prolongated cycling time from 500 to 1300 h compared to that in the blank electrolyte at 0.5 mA cm⁻² with a capacity of 1 mAh cm⁻². Moreover, Li||LiFePO₄ and Li||LiCoO₂ with a high cathode mass loading of > 10 mg cm⁻² can be stably cycled over 180 cycles.

Highlights:
1 Cetyltrimethylammonium cations can shield the repelling force on anions to attract more anions into electric double layer region during lithium plating process, facilitating the formation of inorganic-rich solid-state electrolyte interphase (SEI).
2 An inorganic-rich (N/F-containing species) structure of SEI can be evidenced by the in-depth analysis.
3 The cycling lifetime of Li||Li symmetric cell in the designed electrolyte can be extended from 500 to 1300 h. Moreover, full cells with a high cathode mass loading of >10 mg cm^-2 can be stably cycled over 180 cycles.

Ionic Liquid-Enhanced Assembly of Nanomaterials for Highly Stable Flexible Transparent Electrodes

Jianmin Yang, Li Chang, Xiqi Zhang, Ziquan Cao, Lei Jiang — Mon, 04 Mar 2024 00:00:00 +0000

The controlled assembly of nanomaterials has demonstrated significant potential in advancing technological devices. However, achieving highly efficient and low-loss assembly technique for nanomaterials, enabling the creation of hierarchical structures with distinctive functionalities, remains a formidable challenge. Here, we present a method for nanomaterial assembly enhanced by ionic liquids, which enables the fabrication of highly stable, flexible, and transparent electrodes featuring an organized layered structure. The utilization of hydrophobic and nonvolatile ionic liquids facilitates the production of stable interfaces with water, effectively preventing the sedimentation of 1D/2D nanomaterials assembled at the interface. Furthermore, the interfacially assembled nanomaterial monolayer exhibits an alternate self-climbing behavior, enabling layer-by-layer transfer and the formation of a well-ordered MXene-wrapped silver nanowire network film. The resulting composite film not only demonstrates exceptional photoelectric performance with a sheet resistance of 9.4 Ω sq⁻¹ and 93% transmittance, but also showcases remarkable environmental stability and mechanical flexibility. Particularly noteworthy is its application in transparent electromagnetic interference shielding materials and triboelectric nanogenerator devices. This research introduces an innovative approach to manufacture and tailor functional devices based on ordered nanomaterials.

Highlights:
1 We present a method that utilizes ionic liquid-enhanced nanomaterial assembly to fabricate highly stable and large-area MXene-silver nanowire electrodes with ordered layered structures.
2 This approach emphasizes the use of hydrophobic and nonvolatile ionic liquids, which form stable interfaces with water by reducing interface energy, preventing the sedimentation loss of nanomaterials during assembly.
3 The prepared electrodes not only exhibit excellent optoelectronic properties (9.4 Ω sq⁻¹ sheet resistance and 93% transmittance), but also have exceptional antioxidant capacity.

Correction: Surface Patterning of Metal Zinc Electrode with an In-Region Zincophilic Interface for High-Rate and Long-Cycle-Life Zinc Metal Anode

Wed, 28 Feb 2024 00:00:00 +0000

The undesirable dendrite growth induced by non-planar zinc (Zn) deposition and low Coulombic efficiency resulting from severe side reactions have been long-standing challenges for metallic Zn anodes and substantially impede the practical application of rechargeable aqueous Zn metal batteries (ZMBs). Herein, we present a strategy for achieving a high-rate and long-cycle-life Zn metal anode by patterning Zn foil surfaces and endowing a Zn-Indium (Zn-In) interface in the microchannels. The accumulation of electrons in the microchannel and the zincophilicity of the Zn-In interface promote preferential heteroepitaxial Zn deposition in the microchannel region and enhance the tolerance of the electrode at high current densities. Meanwhile, electron aggregation accelerates the dissolution of non-(002) plane Zn atoms on the array surface, thereby directing the subsequent homoepitaxial Zn deposition on the array surface. Consequently, the planar dendrite-free Zn deposition and long-term cycling stability are achieved (5,050 h at 10.0 mA cm⁻² and 27,000 cycles at 20.0 mA cm⁻²). Furthermore, a Zn/I₂ full cell assembled by pairing with such an anode can maintain good stability for 3,500 cycles at 5.0 C, demonstrating the application potential of the as-prepared ZnIn anode for high-performance aqueous ZMBs.

Highlights:
1 A stable Zn anode was obtained by patterning Zn foil surfaces and endowing a zincphilic interface in microchannels.
2 The accumulation of electrons in the microchannel and the zincphilic interface promoted preferential heteroepitaxial Zn deposition in the microchannel region and subsequent homoepitaxial Zn deposition on the array surface.
3 The Zn symmetrical cells could undergo repeated plating/stripping for more than 25,000 cycles at the current densities of 10 and 20 mA cm⁻².

Building Feedback-Regulation System Through Atomic Design for Highly Active SO2 Sensing

Tue, 27 Feb 2024 00:00:00 +0000

Reasonably constructing an atomic interface is pronouncedly essential for surface-related gas-sensing reaction. Herein, we present an ingenious feedback-regulation system by changing the interactional mode between single Pt atoms and adjacent S species for high-efficiency SO₂ sensing. We found that the single Pt sites on the MoS₂ surface can induce easier volatilization of adjacent S species to activate the whole inert S plane. Reversely, the activated S species can provide a feedback role in tailoring the antibonding-orbital electronic occupancy state of Pt atoms, thus creating a combined system involving S vacancy-assisted single Pt sites (Pt-Vs) to synergistically improve the adsorption ability of SO₂ gas molecules. Furthermore, in situ Raman, ex situ X-ray photoelectron spectroscopy testing and density functional theory analysis demonstrate the intact feedback-regulation system can expand the electron transfer path from single Pt sites to whole Pt-MoS₂ supports in SO₂ gas atmosphere. Equipped with wireless-sensing modules, the final Pt₁-MoS₂-def sensors array can further realize real-time monitoring of SO₂ levels and cloud-data storage for plant growth. Such a fundamental understanding of the intrinsic link between atomic interface and sensing mechanism is thus expected to broaden the rational design of highly effective gas sensors.

Highlights:
1 Feedback-regulation system is established between single Pt sites and MoS₂ supports
2 The Pt1-MoS₂-def can expand the electron transfer path from single Pt sites to whole Pt-MoS₂ supports in SO₂ gas atmosphere.
3 The Pt1-MoS₂-def sensors exhibit high SO₂ responses and extremely low limit of detection (3.14% to 500 ppb SO₂) at room temperature.
4 The Pt1-MoS₂-def sensors array can realize real-time monitoring of SO₂ for plant growth.

Enhancing the Interaction of Carbon Nanotubes by Metal–Organic Decomposition with Improved Mechanical Strength and Ultra-Broadband EMI Shielding Performance

Tue, 27 Feb 2024 00:00:00 +0000

The remarkable properties of carbon nanotubes (CNTs) have led to promising applications in the field of electromagnetic interference (EMI) shielding. However, for macroscopic CNT assemblies, such as CNT film, achieving high electrical and mechanical properties remains challenging, which heavily depends on the tube–tube interactions of CNTs. Herein, we develop a novel strategy based on metal–organic decomposition (MOD) to fabricate a flexible silver–carbon nanotube (Ag–CNT) film. The Ag particles are introduced in situ into the CNT film through annealing of MOD, leading to enhanced tube–tube interactions. As a result, the electrical conductivity of Ag–CNT film is up to 6.82 × 10⁵ S m⁻¹, and the EMI shielding effectiveness of Ag–CNT film with a thickness of ~ 7.8 μm exceeds 66 dB in the ultra-broad frequency range (3–40 GHz). The tensile strength and Young’s modulus of Ag–CNT film increase from 30.09 ± 3.14 to 76.06 ± 6.20 MPa (~ 253%) and from 1.12 ± 0.33 to 8.90 ± 0.97 GPa (~ 795%), respectively. Moreover, the Ag–CNT film exhibits excellent near-field shielding performance, which can effectively block wireless transmission. This innovative approach provides an effective route to further apply macroscopic CNT assemblies to future portable and wearable electronic devices.

Highlights:
1 A strategy based on metal-organic decomposition is proposed to enhance the tube-tube interactions of carbon nanotubes (CNTs).
2 The robust tube-tube interactions of CNTs enhance both EMI shielding performance and mechanical properties of CNT film.
3 This innovative approach provides an effective way to obtain high-performance CNT film.

Tailoring Classical Conditioning Behavior in TiO2 Nanowires: ZnO QDs-Based Optoelectronic Memristors for Neuromorphic Hardware

Tue, 27 Feb 2024 00:00:00 +0000

Neuromorphic hardware equipped with associative learning capabilities presents fascinating applications in the next generation of artificial intelligence. However, research into synaptic devices exhibiting complex associative learning behaviors is still nascent. Here, an optoelectronic memristor based on Ag/TiO₂ Nanowires: ZnO Quantum dots/FTO was proposed and constructed to emulate the biological associative learning behaviors. Effective implementation of synaptic behaviors, including long and short-term plasticity, and learning-forgetting-relearning behaviors, were achieved in the device through the application of light and electrical stimuli. Leveraging the optoelectronic co-modulated characteristics, a simulation of neuromorphic computing was conducted, resulting in a handwriting digit recognition accuracy of 88.9%. Furthermore, a 3 × 7 memristor array was constructed, confirming its application in artificial visual memory. Most importantly, complex biological associative learning behaviors were emulated by mapping the light and electrical stimuli into conditioned and unconditioned stimuli, respectively. After training through associative pairs, reflexes could be triggered solely using light stimuli. Comprehensively, under specific optoelectronic signal applications, the four features of classical conditioning, namely acquisition, extinction, recovery, and generalization, were elegantly emulated. This work provides an optoelectronic memristor with associative behavior capabilities, offering a pathway for advancing brain-machine interfaces, autonomous robots, and machine self-learning in the future.

Highlights:
1 An optoelectronic memristor with bioinspired neuromorphic behavior was proposed based on Ag/TiO₂ Nanowires: ZnO QDs/FTO.
2 The proposed device establishes superior long/short-term synaptic plasticity in response to electrical and light stimuli, and a neuromorphic computing task is effectively implemented based on its optoelectronic performance.
3 The device emulated complex biological associative learning behaviors, including the four features of acquisition, extinction, restoration, and generalization.

Highly Porous Yet Transparent Mechanically Flexible Aerogels Realizing Solar-Thermal Regulatory Cooling

Mon, 26 Feb 2024 00:00:00 +0000

Weakly Polarized Organic Cation-Modified Hydrated Vanadium Oxides for High-Energy Efficiency Aqueous Zinc-Ion Batteries

Xiaoxiao Jia, Chaofeng Liu, Zhi Wang, Di Huang, Guozhong Cao — Thu, 22 Feb 2024 00:00:00 +0000

Vanadium oxides, particularly hydrated forms like V₂O₅·nH₂O (VOH), stand out as promising cathode candidates for aqueous zinc ion batteries due to their adjustable layered structure, unique electronic characteristics, and high theoretical capacities. However, challenges such as vanadium dissolution, sluggish Zn²⁺ diffusion kinetics, and low operating voltage still hinder their direct application. In this study, we present a novel vanadium oxide ([C₆H₆N(CH₃)₃]_1.08V₈O₂₀·0.06H₂O, TMPA-VOH), developed by pre-inserting trimethylphenylammonium (TMPA⁺) cations into VOH. The incorporation of weakly polarized organic cations capitalizes on both ionic pre-intercalation and molecular pre-intercalation effects, resulting in a phase and morphology transition, an expansion of the interlayer distance, extrusion of weakly bonded interlayer water, and a substantial increase in V⁴⁺ content. These modifications synergistically reduce the electrostatic interactions between Zn²⁺ and the V–O lattice, enhancing structural stability and reaction kinetics during cycling. As a result, TMPA-VOH achieves an elevated open circuit voltage and operation voltage, exhibits a large specific capacity (451 mAh g^–1 at 0.1 A g^–1) coupled with high energy efficiency (89%), the significantly-reduced battery polarization, and outstanding rate capability and cycling stability. The concept introduced in this study holds great promise for the development of high-performance oxide-based energy storage materials.

Highlights:
1 A vanadium oxide (TMPA-VOH) is synthesized with trimethylphenylammonium cations chemically pre-inserted into hydrated vanadium oxide.
2 The pre-intercalation of weakly polarized organic cations strategically utilizes both ionic and molecular pre-intercalation effects.
3 TMPA-VOH, with modified crystal structure and morphology, increased V⁴⁺ content, and weakened electrostatic interactions between Zn²⁺ and the V-O lattice, demonstrates enhanced voltage, storage capacity, structural stability, and reaction kinetics.

On-Chip Micro Temperature Controllers Based on Freestanding Thermoelectric Nano Films for Low-Power Electronics

Tue, 20 Feb 2024 00:00:00 +0000

Multidimensional integration and multifunctional component assembly have been greatly explored in recent years to extend Moore’s Law of modern microelectronics. However, this inevitably exacerbates the inhomogeneity of temperature distribution in microsystems, making precise temperature control for electronic components extremely challenging. Herein, we report an on-chip micro temperature controller including a pair of thermoelectric legs with a total area of 50 × 50 μm², which are fabricated from dense and flat freestanding Bi₂Te₃-based thermoelectric nano films deposited on a newly developed nano graphene oxide membrane substrate. Its tunable equivalent thermal resistance is controlled by electrical currents to achieve energy-efficient temperature control for low-power electronics. A large cooling temperature difference of 44.5 K at 380 K is achieved with a power consumption of only 445 μW, resulting in an ultrahigh temperature control capability over 100 K mW⁻¹. Moreover, an ultra-fast cooling rate exceeding 2000 K s⁻¹ and excellent reliability of up to 1 million cycles are observed. Our proposed on-chip temperature controller is expected to enable further miniaturization and multifunctional integration on a single chip for microelectronics.

Highlights:
1 Dense and flat freestanding Bi₂Te₃-based thermoelectric nano films were successfully fabricated by sputtering technology using a newly developed nano graphene oxide membrane as a substrate.
2 On-chip micro temperature controllers were integrated using conventional micro-electromechanical system technology, to achieve energy-efficient temperature control for low-power electronics.
3 The tunable equivalent thermal resistance enables an ultrahigh temperature control capability of 100 K mW⁻¹ and an ultra-fast cooling rate exceeding 2000 K s⁻¹, as well as excellent reliability of up to 1 million cycles.

Enhanced High-Temperature Cycling Stability of Garnet-Based All Solid-State Lithium Battery Using a Multi-Functional Catholyte Buffer Layer

Leqi Zhao, Yijun Zhong, Chencheng Cao, Tony Tang, Zongping Shao — Mon, 19 Feb 2024 00:00:00 +0000

The pursuit of safer and high-performance lithium-ion batteries (LIBs) has triggered extensive research activities on solid-state batteries, while challenges related to the unstable electrode–electrolyte interface hinder their practical implementation. Polymer has been used extensively to improve the cathode-electrolyte interface in garnet-based all-solid-state LIBs (ASSLBs), while it introduces new concerns about thermal stability. In this study, we propose the incorporation of a multi-functional flame-retardant triphenyl phosphate additive into poly(ethylene oxide), acting as a thin buffer layer between LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathode and garnet electrolyte. Through electrochemical stability tests, cycling performance evaluations, interfacial thermal stability analysis and flammability tests, improved thermal stability (capacity retention of 98.5% after 100 cycles at 60 °C, and 89.6% after 50 cycles at 80 °C) and safety characteristics (safe and stable cycling up to 100 °C) are demonstrated. Based on various materials characterizations, the mechanism for the improved thermal stability of the interface is proposed. The results highlight the potential of multi-functional flame-retardant additives to address the challenges associated with the electrode–electrolyte interface in ASSLBs at high temperature. Efficient thermal modification in ASSLBs operating at elevated temperatures is also essential for enabling large-scale energy storage with safety being the primary concern.

Highlights:
1 Thermally stable catholyte buffer layer was fabricated via incorporating a multi-functional flame-retardant triphenyl phosphate additive into poly(ethylene oxide).
2 The optimized catholyte buffer layer enabled thermal and electrochemical stability at interface level, delivering comparable cycling stability of garnet-based all solid-state lithium battery, i.e., capacity retention of 98.5% after 100 cycles at 60 °C, and 89.6% after 50 cycles at 80 °C.
3 Exceptional safety performances were demonstrated, i.e., safely cycling behavior at temperature up to 100 °C and spontaneous fire-extinguishing ability.

Ultraconformable Integrated Wireless Charging Micro-Supercapacitor Skin

Mon, 19 Feb 2024 00:00:00 +0000

Conformable and wireless charging energy storage devices play important roles in enabling the fast development of wearable, non-contact soft electronics. However, current wireless charging power sources are still restricted by limited flexural angles and fragile connection of components, resulting in the failure expression of performance and constraining their further applications in health monitoring wearables and moveable artificial limbs. Herein, we present an ultracompatible skin-like integrated wireless charging micro-supercapacitor, which building blocks (including electrolyte, electrode and substrate) are all evaporated by liquid precursor. Owing to the infiltration and permeation of the liquid, each part of the integrated device attached firmly with each other, forming a compact and all-in-one configuration. In addition, benefitting from the controllable volume of electrode solution precursor, the electrode thickness is easily regulated varying from 11.7 to 112.5 μm. This prepared thin IWC-MSC skin can fit well with curving human body, and could be wireless charged to store electricity into high capacitive micro-supercapacitors (11.39 F cm⁻³) of the integrated device. We believe this work will shed light on the construction of skin-attachable electronics and irregular sensing microrobots.

Highlights:
1 An ultraconformable skin-like integrated wireless charging micro-supercapacitor (IWC-MSC) could be wireless charged to store electricity into high capacitive micro-supercapacitors (11.39 F cm⁻³), and fits well with human surface.
2 Building blocks of IWC-MSC skin are all evaporated by liquid precursor, and each part of the device attached firmly benefitting from the liquid permeation, forming a compact and all-in-one configuration.
3 The electrode thickness easily regulated varying from 11.7 to 112.5 μm by controlling the volume of electrode solution precursor.

A Self-Healing Optoacoustic Patch with High Damage Threshold and Conversion Efficiency for Biomedical Applications

Mon, 19 Feb 2024 00:00:00 +0000

Compared with traditional piezoelectric ultrasonic devices, optoacoustic devices have unique advantages such as a simple preparation process, anti-electromagnetic interference, and wireless long-distance power supply. However, current optoacoustic devices remain limited due to a low damage threshold and energy conversion efficiency, which seriously hinder their widespread applications. In this study, using a self-healing polydimethylsiloxane (PDMS, Fe-Hpdca-PDMS) and carbon nanotube composite, a flexible optoacoustic patch is developed, which possesses the self-healing capability at room temperature, and can even recover from damage induced by cutting or laser irradiation. Moreover, this patch can generate high-intensity ultrasound (> 25 MPa) without the focusing structure. The laser damage threshold is greater than 183.44 mJ cm⁻², and the optoacoustic energy conversion efficiency reaches a major achievement at 10.66 × 10⁻³, compared with other carbon-based nanomaterials and PDMS composites. This patch is also been successfully examined in the application of acoustic flow, thrombolysis, and wireless energy harvesting. All findings in this study provides new insight into designing and fabricating of novel ultrasound devices for biomedical applications.

Highlights:
1 Based on Fe-Hpdca-PDMS and carbon nanotube composite, an optoacoustic patch is developed, which can recover from the damage induced by cutting or laser irradiation at room temperature.
2 The patch has high laser damage threshold (183.44 mJ cm⁻²) and optoacoustic energy conversion efficiency (10.66×10⁻³).
3 The patch has been successfully examined in acoustic flow, thrombolysis, and wireless energy harvesting, which may provide new insights into the field of the design and fabrication of novel ultrasound devices for biomedical applications.

Dual-Atom Nanozyme Eye Drops Attenuate Inflammation and Break the Vicious Cycle in Dry Eye Disease

Mon, 19 Feb 2024 00:00:00 +0000

Dry eye disease (DED) is a major ocular pathology worldwide, causing serious ocular discomfort and even visual impairment. The incidence of DED is gradually increasing with the high-frequency use of electronic products. Although inflammation is core cause of the DED vicious cycle, reactive oxygen species (ROS) play a pivotal role in the vicious cycle by regulating inflammation from upstream. Therefore, current therapies merely targeting inflammation show the failure of DED treatment. Here, a novel dual-atom nanozymes (DAN)-based eye drops are developed. The antioxidative DAN is successfully prepared by embedding Fe and Mn bimetallic single-atoms in N-doped carbon material and modifying it with a hydrophilic polymer. The in vitro and in vivo results demonstrate the DAN is endowed with superior biological activity in scavenging excessive ROS, inhibiting NLRP3 inflammasome activation, decreasing proinflammatory cytokines expression, and suppressing cell apoptosis. Consequently, the DAN effectively alleviate ocular inflammation, promote corneal epithelial repair, recover goblet cell density and tear secretion, thus breaking the DED vicious cycle. Our findings open an avenue to make the DAN as an intervention form to DED and ROS-mediated inflammatory diseases.

Highlights:
1 A dual-atom nanozyme (DAN) was successfully prepared based on Fe and Mn bimetallic single-atom embedded in N-doped carbon material and modified with hydrophilic polymer.
2 The DAN possess excellent enzyme catalytic activity and attenuate dramatically inflammation by inhibiting the reactive oxygen species (ROS)/NLRP3 signal axis.
3 The DAN break the vicious cycle in dry eye disease and is a potential strategy for treating dry eye disease.

Thioacetamide Additive Homogenizing Zn Deposition Revealed by In Situ Digital Holography for Advanced Zn Ion Batteries

Thu, 15 Feb 2024 00:00:00 +0000

Zinc ion batteries are considered as potential energy storage devices due to their advantages of low-cost, high-safety, and high theoretical capacity. However, dendrite growth and chemical corrosion occurring on Zn anode limit their commercialization. These problems can be tackled through the optimization of the electrolyte. However, the screening of electrolyte additives using normal electrochemical methods is time-consuming and labor-intensive. Herein, a fast and simple method based on the digital holography is developed. It can realize the in situ monitoring of electrode/electrolyte interface and provide direct information concerning ion concentration evolution of the diffusion layer. It is effective and time-saving in estimating the homogeneity of the deposition layer and predicting the tendency of dendrite growth, thus able to value the applicability of electrolyte additives. The feasibility of this method is further validated by the forecast and evaluation of thioacetamide additive. Based on systematic characterization, it is proved that the introduction of thioacetamide can not only regulate the interficial ion flux to induce dendrite-free Zn deposition, but also construct adsorption molecule layers to inhibit side reactions of Zn anode. Being easy to operate, capable of in situ observation, and able to endure harsh conditions, digital holography method will be a promising approach for the interfacial investigation of other battery systems.

Highlights:
1 Digital holography can realize the in situ observation of electrode/electrolyte interface and provide dynamic evolution information of the liquid phase of electrode, which is both efficient and effective in investing the interficial electrochemical mechanism and screening electrolyte additives.
2 Thioacetamide electrolyte additive effectively enhances the electrochemical performance of Zn anode by regulating the interficial ion flux to induce dendrite-free Zn deposition and constructing adsorption molecule layers to inhibit side reactions.

All-Covalent Organic Framework Nanofilms Assembled Lithium-Ion Capacitor to Solve the Imbalanced Charge Storage Kinetics

Thu, 15 Feb 2024 00:00:00 +0000

Free-standing covalent organic framework (COFs) nanofilms exhibit a remarkable ability to rapidly intercalate/de-intercalate Li⁺ in lithium-ion batteries, while simultaneously exposing affluent active sites in supercapacitors. The development of these nanofilms offers a promising solution to address the persistent challenge of imbalanced charge storage kinetics between battery-type anode and capacitor-type cathode in lithium-ion capacitors (LICs). Herein, for the first time, custom-made COF_BTMB-TP and COF_TAPB-BPY nanofilms are synthesized as the anode and cathode, respectively, for an all-COF nanofilm-structured LIC. The COF_BTMB-TP nanofilm with strong electronegative–CF₃ groups enables tuning the partial electron cloud density for Li⁺ migration to ensure the rapid anode kinetic process. The thickness-regulated cathodic COF_TAPB-BPY nanofilm can fit the anodic COF nanofilm in the capacity. Due to the aligned 1D channel, 2D aromatic skeleton and accessible active sites of COF nanofilms, the whole COF_TAPB-BPY//COF_BTMB-TP LIC demonstrates a high energy density of 318 mWh cm⁻³ at a high-power density of 6 W cm⁻³, excellent rate capability, good cycle stability with the capacity retention rate of 77% after 5000-cycle. The COF_TAPB-BPY//COF_BTMB-TP LIC represents a new benchmark for currently reported film-type LICs and even film-type supercapacitors. After being comprehensively explored via ex situ XPS, ⁷Li solid-state NMR analyses, and DFT calculation, it is found that the COF_BTMB-TP nanofilm facilitates the reversible conversion of semi-ionic to ionic C–F bonds during lithium storage. COF_BTMB-TP exhibits a strong interaction with Li⁺ due to the C–F, C=O, and C–N bonds, facilitating Li⁺ desolation and absorption from the electrolyte. This work addresses the challenge of imbalanced charge storage kinetics and capacity between the anode and cathode and also pave the way for future miniaturized and wearable LIC devices.

Highlights:
1 An all-covalent organic framework (COF) nanofilm-structured lithium-ion capacitor (LIC) was developed by custom-made COF nanofilms as the anode/cathode.
2 The COF nanofilm-structured LIC exhibits good electrochemical properties via the fast Li⁺ transport kinetics of the anodic COF_BTMB-TP nanofilm and the high specific capacity of the cathodic COF_TAPB-BPY nanofilm.
3 This work can realize the charge storage kinetics and capacity balance of anode/cathode in COF_TAPB-BPY//COF_BTMB-TP LIC.

Covalently Bonded Ni Sites in Black Phosphorene with Electron Redistribution for Efficient Metal-Lightweighted Water Electrolysis

Wed, 14 Feb 2024 00:00:00 +0000

The metal-lightweighted electrocatalysts for water splitting are highly desired for sustainable and economic hydrogen energy deployments, but challengeable. In this work, a low-content Ni-functionalized approach triggers the high capability of black phosphorene (BP) with hydrogen and oxygen evolution reaction (HER/OER) bifunctionality. Through a facile in situ electro-exfoliation route, the ionized Ni sites are covalently functionalized in BP nanosheets with electron redistribution and controllable metal contents. It is found that the as-fabricated Ni-BP electrocatalysts can drive the water splitting with much enhanced HER and OER activities. In 1.0 M KOH electrolyte, the optimized 1.5 wt% Ni-functionalized BP nanosheets have readily achieved low overpotentials of 136 mV for HER and 230 mV for OER at 10 mA cm⁻². Moreover, the covalently bonding between Ni and P has also strengthened the catalytic stability of the Ni-functionalized BP electrocatalyst, stably delivering the overall water splitting for 50 h at 20 mA cm⁻². Theoretical calculations have revealed that Ni–P covalent binding can regulate the electronic structure and optimize the reaction energy barrier to improve the catalytic activity effectively. This work confirms that Ni-functionalized BP is a suitable candidate for electrocatalytic overall water splitting, and provides effective strategies for constructing metal-lightweighted economic electrocatalysts.

Highlights:
1 Black phosphorene (BP) was functionalized by the ionized Ni through an in situ electrochemical exfoliation method.
2 Just 1.5 wt% Ni-functionalized BP can stably deliver the efficient alkaline H₂/O₂ evolution electrocatalysis.
3 Optimized intermediate chemisorption is enabled by Ni–P covalent bonding and electron redistributed surface.

Janus Quasi-Solid Electrolyte Membranes with Asymmetric Porous Structure for High-Performance Lithium-Metal Batteries

Zerui Chen, Wei Zhao, Qian Liu, Yifei Xu, Qinghe Wang, Jinmin Lin, Hao Bin Wu — Wed, 14 Feb 2024 00:00:00 +0000

Quasi-solid electrolytes (QSEs) based on nanoporous materials are promising candidates to construct high-performance Li-metal batteries (LMBs). However, simultaneously boosting the ionic conductivity (σ) and lithium-ion transference number (t₊) of liquid electrolyte confined in porous matrix remains challenging. Herein, we report a novel Janus MOFLi/MSLi QSEs with asymmetric porous structure to inherit the benefits of both mesoporous and microporous hosts. This Janus QSE composed of mesoporous silica and microporous MOF exhibits a neat Li⁺ conductivity of 1.5 × 10^–4 S cm⁻¹ with t₊ of 0.71. A partially de-solvated structure and preference distribution of Li⁺ near the Lewis base O atoms were depicted by MD simulations. Meanwhile, the nanoporous structure enabled efficient ion flux regulation, promoting the homogenous deposition of Li⁺. When incorporated in Li||Cu cells, the MOFLi/MSLi QSEs demonstrated a high Coulombic efficiency of 98.1%, surpassing that of liquid electrolytes (96.3%). Additionally, NCM 622||Li batteries equipped with MOFLi/MSLi QSEs exhibited promising rate performance and could operate stably for over 200 cycles at 1 C. These results highlight the potential of Janus MOFLi/MSLi QSEs as promising candidates for next-generation LMBs.

Highlights:
1 Janus quasi-solid electrolyte membranes with asymmetric porous structure were constructed, showing a high σ_Li⁺ of 1.5 × 10^-4 S cm^-1 and a high t₊ of 0.71.
2 The solvation structures and ion transport dynamics in nanopores have been deciphered, manifesting a concentrated electrolyte-like structure and regulated transport behaviors.
3 Quasi-solid NCM 622||Li cells have been demonstrated to stably cycle for 200 cycles at 1 C, and pouch cell has shown high tolerance for abuse.

Laser-Induced and MOF-Derived Metal Oxide/Carbon Composite for Synergistically Improved Ethanol Sensing at Room temperature

Hyeongtae Lim, Hyeokjin Kwon, Hongki Kang, Jae Eun Jang, Hyuk‑Jun Kwon — Fri, 09 Feb 2024 00:00:00 +0000

Advancements in sensor technology have significantly enhanced atmospheric monitoring. Notably, metal oxide and carbon (MO_x/C) hybrids have gained attention for their exceptional sensitivity and room-temperature sensing performance. However, previous methods of synthesizing MO_x/C composites suffer from problems, including inhomogeneity, aggregation, and challenges in micropatterning. Herein, we introduce a refined method that employs a metal–organic framework (MOF) as a precursor combined with direct laser writing. The inherent structure of MOFs ensures a uniform distribution of metal ions and organic linkers, yielding homogeneous MO_x/C structures. The laser processing facilitates precise micropatterning (< 2 μm, comparable to typical photolithography) of the MO_x/C crystals. The optimized MOF-derived MO_x/C sensor rapidly detected ethanol gas even at room temperature (105 and 18 s for response and recovery, respectively), with a broad range of sensing performance from 170 to 3,400 ppm and a high response value of up to 3,500%. Additionally, this sensor exhibited enhanced stability and thermal resilience compared to previous MOF-based counterparts. This research opens up promising avenues for practical applications in MOF-derived sensing devices.

Highlights:
1 Metal oxide and carbon hybrids (MO_x/C) were micropatterned very rapidly and energy efficiently by direct laser writing.
2 Metal-organic framework was the ideal precursor for fabricating homogeneous MO_x/C hybrids due to regularly spaced metal ions and organic ligands.
3 The fabricated sensor not only demonstrated broad-range gas sensing capability for ethanol gas (170-3,400 ppm) but also exhibited exceptional sensitivity, rapid response and recovery, selectivity, linearity, and thermal stability.

Surface Patterning of Metal Zinc Electrode with an In-Region Zincophilic Interface for High-Rate and Long-Cycle-Life Zinc Metal Anode

Fri, 09 Feb 2024 00:00:00 +0000

Fundamental Understanding of Hydrogen Evolution Reaction on Zinc Anode Surface: A First-Principles Study

Tue, 06 Feb 2024 00:00:00 +0000

Hydrogen evolution reaction (HER) has become a key factor affecting the cycling stability of aqueous Zn-ion batteries, while the corresponding fundamental issues involving HER are still unclear. Herein, the reaction mechanisms of HER on various crystalline surfaces have been investigated by first-principle calculations based on density functional theory. It is found that the Volmer step is the rate-limiting step of HER on the Zn (002) and (100) surfaces, while, the reaction rates of HER on the Zn (101), (102) and (103) surfaces are determined by the Tafel step. Moreover, the correlation between HER activity and the generalized coordination number $\bar{C N}$ of Zn at the surfaces has been revealed. The relatively weaker HER activity on Zn (002) surface can be attributed to the higher $\bar{C N}$ of surface Zn atom. The atomically uneven Zn (002) surface shows significantly higher HER activity than the flat Zn (002) surface as the $\bar{C N}$ of the surface Zn atom is lowered. The $\bar{C N}$ of surface Zn atom is proposed as a key descriptor of HER activity. Tuning the $\bar{C N}$ of surface Zn atom would be a vital strategy to inhibit HER on the Zn anode surface based on the presented theoretical studies. Furthermore, this work provides a theoretical basis for the in-depth understanding of HER on the Zn surface.

Highlights:
1 The reaction mechanisms of hydrogen evolution reaction (HER) on various crystal surfaces of zinc anode have been systematically investigated by first-principle calculations.
2 Both the thermodynamic and kinetic aspects of HER have been studied to reveal the relative HER activity of several crystal surface of zinc anode.
3 The generalized coordination number of surface Zn atoms are proposed as a key descriptor of HER activity of Zn anode.

Discovering Cathodic Biocompatibility for Aqueous Zn–MnO2 Battery: An Integrating Biomass Carbon Strategy

Mon, 05 Feb 2024 00:00:00 +0000

Developing high-performance aqueous Zn-ion batteries from sustainable biomass becomes increasingly vital for large-scale energy storage in the foreseeable future. Therefore, γ-MnO₂ uniformly loaded on N-doped carbon derived from grapefruit peel is successfully fabricated in this work, and particularly the composite cathode with carbon carrier quality percentage of 20 wt% delivers the specific capacity of 391.2 mAh g⁻¹ at 0.1 A g⁻¹, outstanding cyclic stability of 92.17% after 3000 cycles at 5 A g⁻¹, and remarkable energy density of 553.12 Wh kg⁻¹ together with superior coulombic efficiency of ~ 100%. Additionally, the cathodic biosafety is further explored specifically through in vitro cell toxicity experiments, which verifies its tremendous potential in the application of clinical medicine. Besides, Zinc ion energy storage mechanism of the cathode is mainly discussed from the aspects of Jahn–Teller effect and Mn domains distribution combined with theoretical analysis and experimental data. Thus, a novel perspective of the conversion from biomass waste to biocompatible Mn-based cathode is successfully developed.

Highlights:
1 γ-MnO₂ loaded on N-doped biomass carbon from grapefruit peel is firstly developed.
2 The splendid cathodic properties (e.g., coulombic efficiency: ~ 100%, energy density: 553.12 Wh kg⁻¹) are gained.
3 The biomass strategy guaranteed via cytotoxicity test shows a clinical potential.
4 Zn-ion storage efficiency is boosted mainly by regulating Mn–O bond and Mn domains.

Ultra-Efficient and Cost-Effective Platinum Nanomembrane Electrocatalyst for Sustainable Hydrogen Production

Mon, 05 Feb 2024 00:00:00 +0000

Hydrogen production through hydrogen evolution reaction (HER) offers a promising solution to combat climate change by replacing fossil fuels with clean energy sources. However, the widespread adoption of efficient electrocatalysts, such as platinum (Pt), has been hindered by their high cost. In this study, we developed an easy-to-implement method to create ultrathin Pt nanomembranes, which catalyze HER at a cost significantly lower than commercial Pt/C and comparable to non-noble metal electrocatalysts. These Pt nanomembranes consist of highly distorted Pt nanocrystals and exhibit a heterogeneous elastic strain field, a characteristic rarely seen in conventional crystals. This unique feature results in significantly higher electrocatalytic efficiency than various forms of Pt electrocatalysts, including Pt/C, Pt foils, and numerous Pt single-atom or single-cluster catalysts. Our research offers a promising approach to develop highly efficient and cost-effective low-dimensional electrocatalysts for sustainable hydrogen production, potentially addressing the challenges posed by the climate crisis.

Highlights:
1 A percolating network of distorted 2D Pt nanomembranes was synthesized by polymer surface buckling-enabled exfoliation for hydrogen evolution reaction.
2 The 2D Pt nanomembrane enabled important technological applications for its high efficiency, low costs, and good stability, making it potential alternative to commercial Pt/C.
3 Our 2D Pt nanomembranes offer insights into a new mechanism for efficient catalyst design strategy: lattice distortion-induced heterogeneous strain.

MXene Hollow Spheres Supported by a C–Co Exoskeleton Grow MWCNTs for Efficient Microwave Absorption

Ze Wu, Xiuli Tan, Jianqiao Wang, Youqiang Xing, Peng Huang, Bingjue Li, Lei Liu — Fri, 02 Feb 2024 00:00:00 +0000

High-performance microwave absorption (MA) materials must be studied immediately since electromagnetic pollution has become a problem that cannot be disregarded. A straightforward composite material, comprising hollow MXene spheres loaded with C–Co frameworks, was prepared to develop multiwalled carbon nanotubes (MWCNTs). A high impedance and suitable morphology were guaranteed by the C–Co exoskeleton, the attenuation ability was provided by the MWCNTs endoskeleton, and the material performance was greatly enhanced by the layered core–shell structure. When the thickness was only 2.04 mm, the effective absorption bandwidth was 5.67 GHz, and the minimum reflection loss (RL_min) was − 70.70 dB. At a thickness of 1.861 mm, the sample calcined at 700 °C had a RL_min of − 63.25 dB. All samples performed well with a reduced filler ratio of 15 wt%. This paper provides a method for making lightweight core–shell composite MA materials with magnetoelectric synergy.

Highlights:
1 A hollow core–shell structure was constructed with C–Co as the exoskeleton to support the MXene and multiwalled carbon nanotubes (MWCNTs) endoskeleton, with MWCNTs growing toward the center of the sphere.
2 A reflection loss of − 70.70 dB and an effective absorption bandwidth of 5.67 GHz were obtained when the thickness was only 2.04 mm. The powder filler ratio was only 15 wt%.
3 The unique hollow core–shell structure enhanced multiple reflection and scattering losses.

A Sustainable Dual Cross-Linked Cellulose Hydrogel Electrolyte for High-Performance Zinc-Metal Batteries

Haodong Zhang, Xiaotang Gan, Yuyang Yan, Jinping Zhou — Fri, 02 Feb 2024 00:00:00 +0000

Aqueous rechargeable Zn-metal batteries (ARZBs) are considered one of the most promising candidates for grid-scale energy storage. However, their widespread commercial application is largely plagued by three major challenges: The uncontrollable Zn dendrites, notorious parasitic side reactions, and sluggish Zn²⁺ ion transfer. To address these issues, we design a sustainable dual cross-linked cellulose hydrogel electrolyte, which has excellent mechanical strength to inhibit dendrite formation, high Zn²⁺ ions binding capacity to suppress side reaction, and abundant porous structure to facilitate Zn²⁺ ions migration. Consequently, the Zn||Zn cell with the hydrogel electrolyte can cycle stably for more than 400 h under a high current density of 10 mA cm⁻². Moreover, the hydrogel electrolyte also enables the Zn||polyaniline cell to achieve high-rate and long-term cycling performance (> 2000 cycles at 2000 mA g⁻¹). Remarkably, the hydrogel electrolyte is easily accessible and biodegradable, making the ARZBs attractive in terms of scalability and sustainability.

Highlights:
1 A sustainable dual cross-linked cellulose hydrogel with excellent mechanical strength was fabricated from aqueous alkali hydroxide/urea solution using a sequential chemical and physical cross-linking strategy.
2 The hydrogel electrolyte effectively suppresses dendrites growth and side reactions to achieve a stable Zn anode (over 2000 h for Zn||Zn cell), which are proved by a multi-perspective and in-depth mechanism investigation.
3 The hydrogel electrolyte is easily accessible and biodegradable, making the zinc batteries attractive in terms of scalability and sustainability.

Proton-Prompted Ligand Exchange to Achieve High-Efficiency CsPbI3 Quantum Dot Light-Emitting Diodes

Yanming Li, Ming Deng, Xuanyu Zhang, Lei Qian, Chaoyu Xiang — Thu, 01 Feb 2024 00:00:00 +0000

CsPbI₃ perovskite quantum dots (QDs) are ideal materials for the next generation of red light-emitting diodes. However, the low phase stability of CsPbI₃ QDs and long-chain insulating capping ligands hinder the improvement of device performance. Traditional in-situ ligand replacement and ligand exchange after synthesis were often difficult to control. Here, we proposed a new ligand exchange strategy using a proton-prompted in-situ exchange of short 5-aminopentanoic acid ligands with long-chain oleic acid and oleylamine ligands to obtain stable small-size CsPbI₃ QDs. This exchange strategy maintained the size and morphology of CsPbI₃ QDs and improved the optical properties and the conductivity of CsPbI₃ QDs films. As a result, high-efficiency red QD-based light-emitting diodes with an emission wavelength of 645 nm demonstrated a record maximum external quantum efficiency of 24.45% and an operational half-life of 10.79 h.

Highlights:
1 A new proton-promoted in situ ligand exchange strategy based on CsPbI₃ quantum dots.
2 The ligand exchange strategy maintains the quantum confinement effect of quantum dots and significantly improves the stability and photophysical properties of CsPbI₃ quantum dots.
3 The performance of light-emitting diodes based on CsPbI₃ quantum dots is significantly improved, the external quantum efficiency is increased from 18.63% to 24.45%, and the half-operational lifetime is increased by 70 times.

Optoelectronic Synapses Based on MXene/Violet Phosphorus van der Waals Heterojunctions for Visual-Olfactory Crossmodal Perception

Hailong Ma, Huajing Fang, Xinxing Xie, Yanming Liu, He Tian, Yang Chai — Thu, 01 Feb 2024 00:00:00 +0000

The crossmodal interaction of different senses, which is an important basis for learning and memory in the human brain, is highly desired to be mimicked at the device level for developing neuromorphic crossmodal perception, but related researches are scarce. Here, we demonstrate an optoelectronic synapse for vision-olfactory crossmodal perception based on MXene/violet phosphorus (VP) van der Waals heterojunctions. Benefiting from the efficient separation and transport of photogenerated carriers facilitated by conductive MXene, the photoelectric responsivity of VP is dramatically enhanced by 7 orders of magnitude, reaching up to 7.7 A W⁻¹. Excited by ultraviolet light, multiple synaptic functions, including excitatory postsynaptic currents, paired-pulse facilitation, short/long-term plasticity and “learning-experience” behavior, were demonstrated with a low power consumption. Furthermore, the proposed optoelectronic synapse exhibits distinct synaptic behaviors in different gas environments, enabling it to simulate the interaction of visual and olfactory information for crossmodal perception. This work demonstrates the great potential of VP in optoelectronics and provides a promising platform for applications such as virtual reality and neurorobotics.

Highlights:
1 The photoelectric response of violet phosphorus (VP) is significantly enhanced by the MXene/VP van der Waals heterojunctions and the highest photoresponsivity of VP is demonstrated.
2 The first VP-based optoelectronic synapse with essential synaptic behaviours is demonstrated.
3 Proof-of-concept visual-olfactory crossmodal perception based on MXene/VP optoelectronic synapses is explored to mimic neuromorphic vision with multi-sensory interactions.

Molecular Mechanisms of Intracellular Delivery of Nanoparticles Monitored by an Enzyme-Induced Proximity Labeling

Thu, 01 Feb 2024 00:00:00 +0000

Achieving increasingly finely targeted drug delivery to organs, tissues, cells, and even to intracellular biomacromolecules is one of the core goals of nanomedicines. As the delivery destination is refined to cellular and subcellular targets, it is essential to explore the delivery of nanomedicines at the molecular level. However, due to the lack of technical methods, the molecular mechanism of the intracellular delivery of nanomedicines remains unclear to date. Here, we develop an enzyme-induced proximity labeling technology in nanoparticles (nano-EPL) for the real-time monitoring of proteins that interact with intracellular nanomedicines. Poly(lactic-co-glycolic acid) nanoparticles coupled with horseradish peroxidase (HRP) were fabricated as a model (HRP(+)-PNPs) to evaluate the molecular mechanism of nano delivery in macrophages. By adding the labeling probe biotin-phenol and the catalytic substrate H₂O₂ at different time points in cellular delivery, nano-EPL technology was validated for the real-time in situ labeling of proteins interacting with nanoparticles. Nano-EPL achieves the dynamic molecular profiling of 740 proteins to map the intracellular delivery of HRP (+)-PNPs in macrophages over time. Based on dynamic clustering analysis of these proteins, we further discovered that different organelles, including endosomes, lysosomes, the endoplasmic reticulum, and the Golgi apparatus, are involved in delivery with distinct participation timelines. More importantly, the engagement of these organelles differentially affects the drug delivery efficiency, reflecting the spatial–temporal heterogeneity of nano delivery in cells. In summary, these findings highlight a significant methodological advance toward understanding the molecular mechanisms involved in the intracellular delivery of nanomedicines.

Highlights:
1 Novel enzyme-induced proximity labeling technology in nanoparticles (nano-EPL).
2 Nano-EPL enables dynamic molecular mapping of the intracellular delivery of nanoparticles in macrophages.
3 Nano-EPL enables the elucidation of a comprehensive phagosome-centered timeline during the vesicular transportation of nanoparticles, revealing distinct organelle engagement and its differential impact on drug delivery efficiency.

Highly Elastic, Bioresorbable Polymeric Materials for Stretchable, Transient Electronic Systems

Thu, 01 Feb 2024 00:00:00 +0000

Publisher Correction to: Strongly Coupled 2D Transition Metal Chalcogenide-MXene-Carbonaceous Nanoribbon Heterostructures with Ultrafast Ion Transport for Boosting Sodium/Potassium Ions Storage

Thu, 01 Feb 2024 00:00:00 +0000

Combining with the advantages of two-dimensional (2D) nanomaterials, MXenes have shown great potential in next generation rechargeable batteries. Similar with other 2D materials, MXenes generally suffer severe self-agglomeration, low capacity, and unsatisfied durability, particularly for larger sodium/potassium ions, compromising their practical values. In this work, a novel ternary heterostructure self-assembled from transition metal selenides (MSe, M = Cu, Ni, and Co), MXene nanosheets and N-rich carbonaceous nanoribbons (CNRibs) with ultrafast ion transport properties is designed for sluggish sodium-ion (SIB) and potassium-ion (PIB) batteries. Benefiting from the diverse chemical characteristics, the positively charged MSe anchored onto the electronegative hydroxy (–OH) functionalized MXene surfaces through electrostatic adsorption, while the fungal-derived CNRibs bonded with the other side of MXene through amino bridging and hydrogen bonds. This unique MXene-based heterostructure prevents the restacking of 2D materials, increases the intrinsic conductivity, and most importantly, provides ultrafast interfacial ion transport pathways and extra surficial and interfacial storage sites, and thus, boosts the high-rate storage performances in SIB and PIB applications. Both the quantitatively kinetic analysis and the density functional theory (DFT) calculations revealed that the interfacial ion transport is several orders higher than that of the pristine MXenes, which delivered much enhanced Na⁺ (536.3 mAh g⁻¹@ 0.1 A g⁻¹) and K⁺ (305.6 mAh g⁻¹@ 1.0 A g⁻¹ ) storage capabilities and excellent long-term cycling stability. Therefore, this work provides new insights into 2D materials engineering and low-cost, but kinetically sluggish post-Li batteries.

Highlights:
1 Unique “Janus” interfacial assemble strategy of 2D MXene nanosheets was proposed firstly.
2 Ternary heterostructure consisting of high capacity transitional metal chalcogenide, high conductive 2D MXene and N rich fungal carbonaceous matrix was achieved for larger radius Na/K ions storages.
3 The highly accessible surfaces and interfaces of the strongly coupled 2D based ternary heterostructures provide superb surficial pseudocapacitive storages for both Na and K ions with low energy barriers was verified.

Quantum Spin Exchange Interactions to Accelerate the Redox Kinetics in Li–S Batteries

Yu Du, Weijie Chen, Yu Wang, Yue Yu, Kai Guo, Gan Qu, Jianan Zhang — Mon, 29 Jan 2024 00:00:00 +0000

Spin-engineering with electrocatalysts have been exploited to suppress the “shuttle effect” in Li–S batteries. Spin selection, spin-dependent electron mobility and spin potentials in activation barriers can be optimized as quantum spin exchange interactions leading to a significant reduction of the electronic repulsions in the orbitals of catalysts. Herein, we anchor the MgPc molecules on fluorinated carbon nanotubes (MgPc@FCNT), which exhibits the single active Mg sites with axial displacement. According to the density functional theory calculations, the electronic spin polarization in MgPc@FCNT not only increases the adsorption energy toward LiPSs intermediates but also facilitates the tunneling process of electron in Li–S batteries. As a result, the MgPc@FCNT provides an initial capacity of 6.1 mAh cm⁻² even when the high sulfur loading is 4.5 mg cm⁻², and still maintains 5.1 mAh cm⁻² after 100 cycles. This work provides a new perspective to extend the main group single-atom catalysts enabling high-performance Li–S batteries.

Highlights:
1 Compared with the traditional single-atom catalysts (SACs), the Mg SACs with axial displacement is accurately fabricated on the functional carbon nanotubes.
2 The electronic spin polarization modulates the spin density of MgPc, facilitating the LiPSs conversion kinetics in Li-S batteries.
3 The MgPc@FCNT achieves ultra-low capacity decay rate under the high sulfur loading.

An Environment-Tolerant Ion-Conducting Double-Network Composite Hydrogel for High-Performance Flexible Electronic Devices

Wenchao Zhao, Haifeng Zhou, Wenkang Li, Manlin Chen, Min Zhou, Long Zhao — Mon, 29 Jan 2024 00:00:00 +0000

High-performance ion-conducting hydrogels (ICHs) are vital for developing flexible electronic devices. However, the robustness and ion-conducting behavior of ICHs deteriorate at extreme temperatures, hampering their use in soft electronics. To resolve these issues, a method involving freeze–thawing and ionizing radiation technology is reported herein for synthesizing a novel double-network (DN) ICH based on a poly(ionic liquid)/MXene/poly(vinyl alcohol) (PMP DN ICH) system. The well-designed ICH exhibits outstanding ionic conductivity (63.89 mS cm⁻¹ at 25 °C), excellent temperature resistance (− 60–80 °C), prolonged stability (30 d at ambient temperature), high oxidation resistance, remarkable antibacterial activity, decent mechanical performance, and adhesion. Additionally, the ICH performs effectively in a flexible wireless strain sensor, thermal sensor, all-solid-state supercapacitor, and single-electrode triboelectric nanogenerator, thereby highlighting its viability in constructing soft electronic devices. The highly integrated gel structure endows these flexible electronic devices with stable, reliable signal output performance. In particular, the all-solid-state supercapacitor containing the PMP DN ICH electrolyte exhibits a high areal specific capacitance of 253.38 mF cm⁻² (current density, 1 mA cm⁻²) and excellent environmental adaptability. This study paves the way for the design and fabrication of high-performance multifunctional/flexible ICHs for wearable sensing, energy-storage, and energy-harvesting applications.

Highlights:
1 Novel double-network (DN) ion-conducting hydrogel (ICH) based on a poly(ionic liquid)/MXene/poly(vinyl alcohol) system (named PMP DN ICH) was synthesized using freeze–thawing and ionizing radiation technology.
2 The PMP DN ICH possesses a multiple cross-linking mechanism and exhibits outstanding ionic conductivity (63.89 mS cm⁻¹), excellent temperature resistance (−60–80 °C) and decent mechanical performance.
3 The well-designed PMP DN ICH shows considerable potential in wearable sensing, energy storage, and energy harvesting.

Macroporous Directed and Interconnected Carbon Architectures Endow Amorphous Silicon Nanodots as Low-Strain and Fast-Charging Anode for Lithium-Ion Batteries

Zhenwei Li, Meisheng Han, Peilun Yu, Junsheng Lin, Jie Yu — Mon, 29 Jan 2024 00:00:00 +0000

Fabricating low-strain and fast-charging silicon-carbon composite anodes is highly desired but remains a huge challenge for lithium-ion batteries. Herein, we report a unique silicon-carbon composite fabricated by uniformly dispersing amorphous Si nanodots (SiNDs) in carbon nanospheres (SiNDs/C) that are welded on the wall of the macroporous carbon framework (MPCF) by vertical graphene (VG), labeled as MPCF@VG@SiNDs/C. The high dispersity and amorphous features of ultrasmall SiNDs (~ 0.7 nm), the flexible and directed electron/Li⁺ transport channels of VG, and the MPCF impart the MPCF@VG@SiNDs/C more lithium storage sites, rapid Li⁺ transport path, and unique low-strain property during Li⁺ storage. Consequently, the MPCF@VG@SiNDs/C exhibits high cycle stability (1301.4 mAh g⁻¹ at 1 A g⁻¹ after 1000 cycles without apparent decay) and high rate capacity (910.3 mAh g⁻¹, 20 A g⁻¹) in half cells based on industrial electrode standards. The assembled pouch full cell delivers a high energy density (1694.0 Wh L⁻¹; 602.8 Wh kg⁻¹) and an excellent fast-charging capability (498.5 Wh kg⁻¹, charging for 16.8 min at 3 C). This study opens new possibilities for preparing advanced silicon-carbon composite anodes for practical applications.

Highlights:
1 MPCF@VG@SiNDs/C, constructed by uniformly dispersing amorphous Si nanodots in carbon nanospheres that are welded on the wall of the macroporous carbon frameworks by vertical graphene, is synthesized and has achieved a few kilogram production per batch.
2 Finite element imitation reveals that amorphous Si nanodots with high dispersity in carbon nanosphere can achieve ultra-low stress and strain values during lithiation.
3 Unique low-strain property and fast-charging capability are achieved under industrial electrode conditions.

Ultrathin Zincophilic Interphase Regulated Electric Double Layer Enabling Highly Stable Aqueous Zinc-Ion Batteries

Thu, 25 Jan 2024 00:00:00 +0000

The practical application of aqueous zinc-ion batteries for large-grid scale systems is still hindered by uncontrolled zinc dendrite and side reactions. Regulating the electrical double layer via the electrode/electrolyte interface layer is an effective strategy to improve the stability of Zn anodes. Herein, we report an ultrathin zincophilic ZnS layer as a model regulator. At a given cycling current, the cell with Zn@ZnS electrode displays a lower potential drop over the Helmholtz layer (stern layer) and a suppressed diffuse layer, indicating the regulated charge distribution and decreased electric double layer repulsion force. Boosted zinc adsorption sites are also expected as proved by the enhanced electric double-layer capacitance. Consequently, the symmetric cell with the ZnS protection layer can stably cycle for around 3,000 h at 1 mA cm⁻² with a lower overpotential of 25 mV. When coupled with an I₂/AC cathode, the cell demonstrates a high rate performance of 160 mAh g⁻¹ at 0.1 A g⁻¹ and long cycling stability of over 10,000 cycles at 10 A g⁻¹. The Zn||MnO₂ also sustains both high capacity and long cycling stability of 130 mAh g⁻¹ after 1,200 cycles at 0.5 A g⁻¹.

Highlights:
1 Electric double-layer regulation enabled by an ultrathin multifunctional solid electrolyte interphase layer with zincophilicity and rapid transport kinetics.
2 Lowered potential drop over the Helmholtz layer and suppressed diffuse layer.
3 Inhibited side reactions and uniform zinc deposition.

Versatile MXene Gels Assisted by Brief and Low-Strength Centrifugation

Weiyan Yu, Yi Yang, Yunjing Wang, Lulin Hu, Jingcheng Hao, Lu Xu, Weimin Liu — Mon, 22 Jan 2024 00:00:00 +0000

Due to the mutual repulsion between their hydrophilic surface terminations and the high surface energy facilitating their random restacking, 2D MXene nanosheets usually cannot self-assemble into 3D macroscopic gels with various applications in the absence of proper linking agents. In this work, a rapid spontaneous gelation of Ti₃C₂T_x MXene with a very low dispersion concentration of 0.5 mg mL⁻¹ into multifunctional architectures under moderate centrifugation is illustrated. The as-prepared MXene gels exhibit reconfigurable internal structures and tunable rheological, tribological, electrochemical, infrared-emissive and photothermal-conversion properties based on the pH-induced changes in the surface chemistry of Ti₃C₂T_x nanosheets. By adopting a gel with optimized pH value, high lubrication, exceptional specific capacitances (~ 635 and ~ 408 F g⁻¹ at 5 and 100 mV s⁻¹, respectively), long-term capacitance retention (~ 96.7% after 10,000 cycles) and high-precision screen- or extrusion-printing into different high-resolution anticounterfeiting patterns can be achieved, thus displaying extensive potential applications in the fields of semi-solid lubrication, controllable devices, supercapacitors, information encryption and infrared camouflaging.

Highlights:
1 A low-strength-centrifugation-assisted approach for rapid gelation of Ti₃C₂T_x MXene with a very low dispersion concentration into multifunctional 3D architectures is developed.
2 On the basis of pH-induced surface termination changes, the MXene gels exhibit reconfigurable internal structures and tunable rheological, tribological, electrochemical, infrared-emissive and photothermal-conversion properties.
3 By adopting a gel with optimized pH value, high lubrication, remarkable capacitance, long-term capacitance retention and high-precision screen- or extrusion-printing into high-resolution anticounterfeiting patterns can be achieved.

Novel Perovskite Oxide Hybrid Nanofibers Embedded with Nanocatalysts for Highly Efficient and Durable Electrodes in Direct CO2 Electrolysis

Akromjon Akhmadjonov, Kyung Taek Bae, Kang Taek Lee — Mon, 22 Jan 2024 00:00:00 +0000

The unique characteristics of nanofibers in rational electrode design enable effective utilization and maximizing material properties for achieving highly efficient and sustainable CO₂ reduction reactions (CO₂RRs) in solid oxide electrolysis cells (SOECs). However, practical application of nanofiber-based electrodes faces challenges in establishing sufficient interfacial contact and adhesion with the dense electrolyte. To tackle this challenge, a novel hybrid nanofiber electrode, La_0.6Sr_0.4Co_0.15Fe_0.8Pd_0.05O_3−δ (H-LSCFP), is developed by strategically incorporating low aspect ratio crushed LSCFP nanofibers into the excess porous interspace of a high aspect ratio LSCFP nanofiber framework synthesized via electrospinning technique. After consecutive treatment in 100% H₂ and CO₂ at 700 °C, LSCFP nanofibers form a perovskite phase with in situ exsolved Co metal nanocatalysts and a high concentration of oxygen species on the surface, enhancing CO₂ adsorption. The SOEC with the H-LSCFP electrode yielded an outstanding current density of 2.2 A cm⁻² in CO₂ at 800 °C and 1.5 V, setting a new benchmark among reported nanofiber-based electrodes. Digital twinning of the H-LSCFP reveals improved contact adhesion and increased reaction sites for CO₂RR. The present work demonstrates a highly catalytically active and robust nanofiber-based fuel electrode with a hybrid structure, paving the way for further advancements and nanofiber applications in CO₂-SOECs.

Highlights:
1 The novel hybrid structured nanofiber electrode, incorporating crushed nanofibers into the nanofiber network, is designed to effectively resolve the issue of insufficient interfacial bonding of porous nanofiber electrodes on solid electrolyte interfaces.
2 The hybrid nanofibers are covered with in situ exsolved metal nanocatalysts to enhance CO₂ reduction reaction rate.
3 Electrochemical and microstructure 3D reconstruction analyses confirmed the hybrid structure’s efficiency in improving the contact area at the porous-solid interface, leading to an increase in reaction sites.

Flexible, Transparent and Conductive Metal Mesh Films with Ultra-High FoM for Stretchable Heating and Electromagnetic Interference Shielding

Mon, 22 Jan 2024 00:00:00 +0000

Despite the growing demand for transparent conductive films in smart and wearable electronics for electromagnetic interference (EMI) shielding, achieving a flexible EMI shielding film, while maintaining a high transmittance remains a significant challenge. Herein, a flexible, transparent, and conductive copper (Cu) metal mesh film for EMI shielding is fabricated by self-forming crackle template method and electroplating technique. The Cu mesh film shows an ultra-low sheet resistance (0.18 Ω □⁻¹), high transmittance (85.8%@550 nm), and ultra-high figure of merit (> 13,000). It also has satisfactory stretchability and mechanical stability, with a resistance increases of only 1.3% after 1,000 bending cycles. As a stretchable heater (ε > 30%), the saturation temperature of the film can reach over 110 °C within 60 s at 1.00 V applied voltage. Moreover, the metal mesh film exhibits outstanding average EMI shielding effectiveness of 40.4 dB in the X-band at the thickness of 2.5 μm. As a demonstration, it is used as a transparent window for shielding the wireless communication electromagnetic waves. Therefore, the flexible and transparent conductive Cu mesh film proposed in this work provides a promising candidate for the next-generation EMI shielding applications.

Highlights:
1 A transparent, conductive, and flexible metal mesh film has been developed by a low-cost, uniform self-forming crackle template and electroplating strategy.
2 The Cu mesh films show an ultra-low sheet resistance (0.18 Ω □⁻¹), high transmittance (85.8%@550 nm), high figure of merit (> 13,000), excellent stretchability and mechanical stability.
3 The metal mesh film can be used as a flexible heater and electromagnetic interference shielding film (40.4 dB at 2.5 μm).

Moderate Fields, Maximum Potential: Achieving High Records with Temperature-Stable Energy Storage in Lead-Free BNT-Based Ceramics

Thu, 18 Jan 2024 00:00:00 +0000

The increasing awareness of environmental concerns has prompted a surge in the exploration of lead-free, high-power ceramic capacitors. Ongoing efforts to develop lead-free dielectric ceramics with exceptional energy-storage performance (ESP) have predominantly relied on multi-component composite strategies, often accomplished under ultrahigh electric fields. However, this approach poses challenges in insulation and system downsizing due to the necessary working voltage under such conditions. Despite extensive study, bulk ceramics of (Bi_0.5Na_0.5)TiO₃ (BNT), a prominent lead-free dielectric ceramic family, have seldom achieved a recoverable energy-storage (ES) density (W_rec) exceeding 7 J cm⁻³. This study introduces a novel approach to attain ceramic capacitors with high ESP under moderate electric fields by regulating permittivity based on a linear dielectric model, enhancing insulation quality, and engineering domain structures through chemical formula optimization. The incorporation of SrTiO₃ (ST) into the BNT matrix is revealed to reduce the dielectric constant, while the addition of Bi(Mg_2/3Nb_1/3)O₃ (BMN) aids in maintaining polarization. Additionally, the study elucidates the methodology to achieve high ESP at moderate electric fields ranging from 300 to 500 kV cm⁻¹. In our optimized composition, 0.5(Bi_0.5Na_0.4K_0.1)TiO₃–0.5(2/3ST-1/3BMN) (B-0.5SB) ceramics, we achieved a W_rec of 7.19 J cm⁻³ with an efficiency of 93.8% at 460 kV cm⁻¹. Impressively, the B-0.5SB ceramics exhibit remarkable thermal stability between 30 and 140 °C under 365 kV cm⁻¹, maintaining a W_rec exceeding 5 J cm⁻³. This study not only establishes the B-0.5SB ceramics as promising candidates for ES materials but also demonstrates the feasibility of optimizing ESP by modifying the dielectric constant under specific electric field conditions. Simultaneously, it provides valuable insights for the future design of ceramic capacitors with high ESP under constraints of limited electric field.

Highlights:
1 Achieving ultrahigh energy-storage density (7.19 J cm⁻³) and outstanding storage efficiency (93.8%) at 460 kV cm⁻¹ in BNT-based relaxor ferroelectric ceramics under a moderate electric field.
2 Superior energy-storage performance accomplished through meticulous regulation of permittivity, enhancement of insulation quality, and strategic domain engineering via chemical formula optimization.
3 The intricate structure–property relationship elucidated with precision using high-resolution transmission electron microscopy.

Strain-Induced Surface Interface Dual Polarization Constructs PML-Cu/Bi12O17Br2 High-Density Active Sites for CO2 Photoreduction

Tue, 16 Jan 2024 00:00:00 +0000

The insufficient active sites and slow interfacial charge transfer of photocatalysts restrict the efficiency of CO₂ photoreduction. The synchronized modulation of the above key issues is demanding and challenging. Herein, strain-induced strategy is developed to construct the Bi–O-bonded interface in Cu porphyrin-based monoatomic layer (PML-Cu) and Bi₁₂O₁₇Br₂ (BOB), which triggers the surface interface dual polarization of PML-Cu/BOB (PBOB). In this multi-step polarization, the built-in electric field formed between the interfaces induces the electron transfer from conduction band (CB) of BOB to CB of PML-Cu and suppresses its reverse migration. Moreover, the surface polarization of PML-Cu further promotes the electron converge in Cu atoms. The introduction of PML-Cu endows a high density of dispersed Cu active sites on the surface of PBOB, significantly promoting the adsorption and activation of CO₂ and CO desorption. The conversion rate of CO₂ photoreduction to CO for PBOB can reach 584.3 μmol g⁻¹, which is 7.83 times higher than BOB and 20.01 times than PML-Cu. This work offers valuable insights into multi-step polarization regulation and active site design for catalysts.

Highlights:
1 Strain induces coupling in Bi₁₂O₁₇Br₂ and Cu porphyrin-based monoatomic layer (PML-Cu), constructing Bi–O bonding interface in PML-Cu/BOB (PBOB).
2 Surface interface dual polarization boosts internal electric field, promoting electron transfer.
3 PML-Cu provides high density of dispersed active Cu sites in PBOB, enhancing CO₂ photoreduction.

Enhancing Green Ammonia Electrosynthesis Through Tuning Sn Vacancies in Sn-Based MXene/MAX Hybrids

Tue, 16 Jan 2024 00:00:00 +0000

Renewable energy driven N₂ electroreduction with air as nitrogen source holds great promise for realizing scalable green ammonia production. However, relevant out-lab research is still in its infancy. Herein, a novel Sn-based MXene/MAX hybrid with abundant Sn vacancies, Sn@Ti₂CT_X/Ti₂SnC–V, was synthesized by controlled etching Sn@Ti₂SnC MAX phase and demonstrated as an efficient electrocatalyst for electrocatalytic N₂ reduction. Due to the synergistic effect of MXene/MAX heterostructure, the existence of Sn vacancies and the highly dispersed Sn active sites, the obtained Sn@Ti₂CT_X/Ti₂SnC–V exhibits an optimal NH₃ yield of 28.4 µg h⁻¹ mg_cat⁻¹ with an excellent FE of 15.57% at − 0.4 V versus reversible hydrogen electrode in 0.1 M Na₂SO₄, as well as an ultra-long durability. Noticeably, this catalyst represents a satisfactory NH₃ yield rate of 10.53 µg h⁻¹ mg⁻¹ in the home-made simulation device, where commercial electrochemical photovoltaic cell was employed as power source, air and ultrapure water as feed stock. The as-proposed strategy represents great potential toward ammonia production in terms of financial cost according to the systematic technical economic analysis. This work is of significance for large-scale green ammonia production.

Highlights:
1 Sn-based MAX/MXene hybrids with abundant Sn vacancies, Sn@Ti₂CTX/Ti₂SnC–V, fabricated by controlled etching method, are demonstrated to be an excellent electrocatalyst for N₂ electroreduction.
2 An economic “NH₃ farm” has been developed based on Sn@Ti₂CTX/Ti₂SnC–V electrode, demonstrated by a commercial electrochemical photovoltaic cell, which may open a novel avenue for solar energy-driven synthesis of ammonia directly from air and water.
3 The potential of the “NH₃ farm” was demonstrated by a systematic technical economic analysis.

A Generic Strategy to Create Mechanically Interlocked Nanocomposite/Hydrogel Hybrid Electrodes for Epidermal Electronics

Fri, 12 Jan 2024 00:00:00 +0000

Stretchable electronics are crucial enablers for next-generation wearables intimately integrated into the human body. As the primary compliant conductors used in these devices, metallic nanostructure/elastomer composites often struggle to form conformal contact with the textured skin. Hybrid electrodes have been consequently developed based on conductive nanocomposite and soft hydrogels to establish seamless skin-device interfaces. However, chemical modifications are typically needed for reliable bonding, which can alter their original properties. To overcome this limitation, this study presents a facile fabrication approach for mechanically interlocked nanocomposite/hydrogel hybrid electrodes. In this physical process, soft microfoams are thermally laminated on silver nanowire nanocomposites as a porous interface, which forms an interpenetrating network with the hydrogel. The microfoam-enabled bonding strategy is generally compatible with various polymers. The resulting interlocked hybrids have a 28-fold improved interfacial toughness compared to directly stacked hybrids. These electrodes achieve firm attachment to the skin and low contact impedance using tissue-adhesive hydrogels. They have been successfully integrated into an epidermal sleeve to distinguish hand gestures by sensing muscle contractions. Interlocked nanocomposite/hydrogel hybrids reported here offer a promising platform to combine the benefits of both materials for epidermal devices and systems.

Highlights:
1 Nanocomposite/hydrogel hybrid electrodes are created with high interfacial toughness by introducing soft microfoams as the mechanically interlocking layer.
2 In the hybrid electrodes, silver nanowires and hydrogels are electrically connected through the porous microfoams, achieving high conductivity and low contact impedance for high-quality biopotential recordings.
3 The microfoam-enabled bonding strategy is generally applicable to diverse polymer substrates.

Highly Efficient Aligned Ion-Conducting Network and Interface Chemistries for Depolarized All-Solid-State Lithium Metal Batteries

Fri, 12 Jan 2024 00:00:00 +0000

Improving the long-term cycling stability and energy density of all-solid-state lithium (Li)-metal batteries (ASSLMBs) at room temperature is a severe challenge because of the notorious solid–solid interfacial contact loss and sluggish ion transport. Solid electrolytes are generally studied as two-dimensional (2D) structures with planar interfaces, showing limited interfacial contact and further resulting in unstable Li/electrolyte and cathode/electrolyte interfaces. Herein, three-dimensional (3D) architecturally designed composite solid electrolytes are developed with independently controlled structural factors using 3D printing processing and post-curing treatment. Multiple-type electrolyte films with vertical-aligned micro-pillar (p-3DSE) and spiral (s-3DSE) structures are rationally designed and developed, which can be employed for both Li metal anode and cathode in terms of accelerating the Li⁺ transport within electrodes and reinforcing the interfacial adhesion. The printed p-3DSE delivers robust long-term cycle life of up to 2600 cycles and a high critical current density of 1.92 mA cm⁻². The optimized electrolyte structure could lead to ASSLMBs with a superior full-cell areal capacity of 2.75 mAh cm⁻² (LFP) and 3.92 mAh cm⁻² (NCM811). This unique design provides enhancements for both anode and cathode electrodes, thereby alleviating interfacial degradation induced by dendrite growth and contact loss. The approach in this study opens a new design strategy for advanced composite solid polymer electrolytes in ASSLMBs operating under high rates/capacities and room temperature.

Highlights:
1 This study introduces an innovative 3D-printed electrolyte with vertically aligned ion transport network, which contains well-dispersed nanoscale Ta-doped Li₇La₃Zr₂O₁₂ in a poly(ethylene glycol) diacrylate matrix.
2 The 3DSE architecture enables efficient ion transport across the Li/electrolyte and electrolyte/cathode interfaces, which allows for increased active material mass loading and enhanced interfacial adhesion.
3 The p-3DSE Li symmetric cell displays an impressive critical current density value of 1.92 mA cm⁻² and stable operation for 2600 h at room temperature. Full cells using p-3DSE achieve notable areal capacities.

3D-Printed Carbon-Based Conformal Electromagnetic Interference Shielding Module for Integrated Electronics

Fri, 12 Jan 2024 00:00:00 +0000

Electromagnetic interference shielding (EMI SE) modules are the core component of modern electronics. However, the traditional metal-based SE modules always take up indispensable three-dimensional space inside electronics, posing a major obstacle to the integration of electronics. The innovation of integrating 3D-printed conformal shielding (c-SE) modules with packaging materials onto core electronics offers infinite possibilities to satisfy ideal SE function without occupying additional space. Herein, the 3D printable carbon-based inks with various proportions of graphene and carbon nanotube nanoparticles are well-formulated by manipulating their rheological peculiarity. Accordingly, the free-constructed architectures with arbitrarily-customized structure and multifunctionality are created via 3D printing. In particular, the SE performance of 3D-printed frame is up to 61.4 dB, simultaneously accompanied with an ultralight architecture of 0.076 g cm⁻³ and a superhigh specific shielding of 802.4 dB cm³ g⁻¹. Moreover, as a proof-of-concept, the 3D-printed c-SE module is in situ integrated into core electronics, successfully replacing the traditional metal-based module to afford multiple functions for electromagnetic compatibility and thermal dissipation. Thus, this scientific innovation completely makes up the blank for assembling carbon-based c-SE modules and sheds a brilliant light on developing the next generation of high-performance shielding materials with arbitrarily-customized structure for integrated electronics.

Highlights:
1 3D printable functional inks incorporated with graphene and carbon nanotube nanoparticles were well-formulated by manipulating their rheological performance
2 The frame with ultralight structure (0.076 g cm⁻³) and high-efficiency electromagnetic interference shielding (61.4 dB) was assembled
3 3D-printed c-SE module was in situ integrated onto the electronics, affording multiple functions of electromagnetic compatibility and thermal dissipation.

Tailoring MXene Thickness and Functionalization for Enhanced Room-Temperature Trace NO2 Sensing

Muhammad Hilal, Woochul Yang, Yongha Hwang, Wanfeng Xie — Fri, 12 Jan 2024 00:00:00 +0000

In this study, precise control over the thickness and termination of Ti₃C₂T_X MXene flakes is achieved to enhance their electrical properties, environmental stability, and gas-sensing performance. Utilizing a hybrid method involving high-pressure processing, stirring, and immiscible solutions, sub-100 nm MXene flake thickness is achieved within the MXene film on the Si-wafer. Functionalization control is achieved by defunctionalizing MXene at 650 °C under vacuum and H₂ gas in a CVD furnace, followed by refunctionalization with iodine and bromine vaporization from a bubbler attached to the CVD. Notably, the introduction of iodine, which has a larger atomic size, lower electronegativity, reduce shielding effect, and lower hydrophilicity (contact angle: 99°), profoundly affecting MXene. It improves the surface area (36.2 cm² g⁻¹), oxidation stability in aqueous/ambient environments (21 days/80 days), and film conductivity (749 S m⁻¹). Additionally, it significantly enhances the gas-sensing performance, including the sensitivity (0.1119 Ω ppm⁻¹), response (0.2% and 23% to 50 ppb and 200 ppm NO₂), and response/recovery times (90/100 s). The reduced shielding effect of the –I-terminals and the metallic characteristics of MXene enhance the selectivity of I-MXene toward NO₂. This approach paves the way for the development of stable and high-performance gas-sensing two-dimensional materials with promising prospects for future studies.

Highlights:
1 Gas-phase functionalization of X-MXene (X = –F, –OH, –O, –Br, –I) films crafted from sub-100 nm thin MXene flakes for highly sensitive NO₂ sensors.
2 I-MXene-based senor exhibited significant sensing performances toward trace NO₂ at room temperature.
3 The hydrophobicity, larger atomic size, lower electronegativity, and reduced shielding of -I contribute to the excellent sensing enhancement of I-MXene.

Construction of a High-Performance Composite Solid Electrolyte Through In-Situ Polymerization within a Self-Supported Porous Garnet Framework

An‑Giang Nguyen, Min‑Ho Lee, Jaekook Kim, Chan‑Jin Park — Fri, 12 Jan 2024 00:00:00 +0000

Composite solid electrolytes (CSEs) have emerged as promising candidates for safe and high-energy–density solid-state lithium metal batteries (SSLMBs). However, concurrently achieving exceptional ionic conductivity and interface compatibility between the electrolyte and electrode presents a significant challenge in the development of high-performance CSEs for SSLMBs. To overcome these challenges, we present a method involving the in-situ polymerization of a monomer within a self-supported porous Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZT) to produce the CSE. The synergy of the continuous conductive LLZT network, well-organized polymer, and their interface can enhance the ionic conductivity of the CSE at room temperature. Furthermore, the in-situ polymerization process can also construct the integration and compatibility of the solid electrolyte–solid electrode interface. The synthesized CSE exhibited a high ionic conductivity of 1.117 mS cm⁻¹, a significant lithium transference number of 0.627, and exhibited electrochemical stability up to 5.06 V vs. Li/Li⁺ at 30 °C. Moreover, the Li|CSE|LiNi_0.8Co_0.1Mn_0.1O₂ cell delivered a discharge capacity of 105.1 mAh g⁻¹ after 400 cycles at 0.5 C and 30 °C, corresponding to a capacity retention of 61%. This methodology could be extended to a variety of ceramic, polymer electrolytes, or battery systems, thereby offering a viable strategy to improve the electrochemical properties of CSEs for high-energy–density SSLMBs.

Highlights:
1 A scalable tape-casting method produces self-supported porous Li_6.4La₃Zr_1.4Ta_0.6O₁₂.
2 Combining the in-situ polymerization approach, a composite solid electrolyte with superior electrochemical properties is fabricated.
3 Solid-state Li|CSE|LiNi_0.8Co_0.1Mn_0.1O₂ cells show remarkable cyclability and rate capability.
4 LiF-and B-rich interphase layers mitigate interfacial reactions, enhancing solid-state battery performance.

Polarizable Additive with Intermediate Chelation Strength for Stable Aqueous Zinc-Ion Batteries

Fri, 12 Jan 2024 00:00:00 +0000

Aqueous zinc-ion batteries are promising due to inherent safety, low cost, low toxicity, and high volumetric capacity. However, issues of dendrites and side reactions between zinc metal anode and the electrolyte need to be solved for extended storage and cycle life. Here, we proposed that an electrolyte additive with an intermediate chelation strength of zinc ion—strong enough to exclude water molecules from the zinc metal-electrolyte interface and not too strong to cause a significant energy barrier for zinc ion dissociation—can benefit the electrochemical stability by suppressing hydrogen evolution reaction, overpotential growth, and dendrite formation. Penta-sodium diethylene-triaminepentaacetic acid salt was selected for such a purpose. It has a suitable chelating ability in aqueous solutions to adjust solvation sheath and can be readily polarized under electrical loading conditions to further improve the passivation. Zn||Zn symmetric cells can be stably operated over 3500 h at 1 mA cm⁻². Zn||NH₄V₄O₁₀ full cells with the additive show great cycling stability with 84.6% capacity retention after 500 cycles at 1 A g⁻¹. Since the additive not only reduces H₂ evolution and corrosion but also modifies Zn²⁺ diffusion and deposition, highlyreversible Zn electrodes can be achieved as verified by the experimental results. Our work offers a practical approach to the logical design of reliable electrolytes for high-performance aqueous batteries.

Highlights:
1 Design principle of a reliable electrolyte based on chelation strength is proposed for high-performance aqueous batteries.
2 The addition of penta-sodium diethylene-triaminepentaacetic acid salt is effective in dynamically modulating anode/electrolyte interface, inhibiting water-related side reactions, and mitigating dendrite generation on zinc anodes.
3 Symmetrical, Zn||Cu half and Zn||NH₄V₄O₁₀ full cells using the new electrolyte exhibit improved electrochemical performance.

Interfacial Electronic Modulation of Dual-Monodispersed Pt–Ni3S2 as Efficacious Bi-Functional Electrocatalysts for Concurrent H2 Evolution and Methanol Selective Oxidation

Thu, 11 Jan 2024 00:00:00 +0000

Constructing the efficacious and applicable bi-functional electrocatalysts and establishing out the mechanisms of organic electro-oxidation by replacing anodic oxygen evolution reaction (OER) are critical to the development of electrochemically-driven technologies for efficient hydrogen production and avoid CO₂ emission. Herein, the hetero-nanocrystals between monodispersed Pt (~ 2 nm) and Ni₃S₂ (~ 9.6 nm) are constructed as active electrocatalysts through interfacial electronic modulation, which exhibit superior bi-functional activities for methanol selective oxidation and H₂ generation. The experimental and theoretical studies reveal that the asymmetrical charge distribution at Pt–Ni₃S₂ could be modulated by the electronic interaction at the interface of dual-monodispersed heterojunctions, which thus promote the adsorption/desorption of the chemical intermediates at the interface. As a result, the selective conversion from CH₃OH to formate is accomplished at very low potentials (1.45 V) to attain 100 mA cm⁻² with high electronic utilization rate (~ 98%) and without CO₂ emission. Meanwhile, the Pt–Ni₃S₂ can simultaneously exhibit a broad potential window with outstanding stability and large current densities for hydrogen evolution reaction (HER) at the cathode. Further, the excellent bi-functional performance is also indicated in the coupled methanol oxidation reaction (MOR)//HER reactor by only requiring a cell voltage of 1.60 V to achieve a current density of 50 mA cm⁻² with good reusability.

Highlights:
1 The well-conceived Pt–Ni₃S₂ heteronanocrystals with dual-monodispersed characteristics are synthesized through interfacial electronic modulation.
2 The asymmetrical charge distribution at Pt–Ni₃S₂ hetero-interface results in the formation of high-valent Ni sites and negatively-charged Pt^δ−.
3 It eventually accelerates water dissociation and achieves the steady concurrent generation of value-added formate and hydrogen.

Textured Asymmetric Membrane Electrode Assemblies of Piezoelectric Phosphorene and Ti3C2Tx MXene Heterostructures for Enhanced Electrochemical Stability and Kinetics in LIBs

Mon, 08 Jan 2024 00:00:00 +0000

Black phosphorus with a superior theoretical capacity (2596 mAh g⁻¹) and high conductivity is regarded as one of the powerful candidates for lithium-ion battery (LIB) anode materials, whereas the severe volume expansion and sluggish kinetics still impede its applications in LIBs. By contrast, the exfoliated two-dimensional phosphorene owns negligible volume variation, and its intrinsic piezoelectricity is considered to be beneficial to the Li-ion transfer kinetics, while its positive influence has not been discussed yet. Herein, a phosphorene/MXene heterostructure-textured nanopiezocomposite is proposed with even phosphorene distribution and enhanced piezo-electrochemical coupling as an applicable free-standing asymmetric membrane electrode beyond the skin effect for enhanced Li-ion storage. The experimental and simulation analysis reveals that the embedded phosphorene nanosheets not only provide abundant active sites for Li-ions, but also endow the nanocomposite with favorable piezoelectricity, thus promoting the Li-ion transfer kinetics by generating the piezoelectric field serving as an extra accelerator. By waltzing with the MXene framework, the optimized electrode exhibits enhanced kinetics and stability, achieving stable cycling performances for 1,000 cycles at 2 A g⁻¹, and delivering a high reversible capacity of 524 mAh g⁻¹ at − 20 ℃, indicating the positive influence of the structural merits of self-assembled nanopiezocomposites on promoting stability and kinetics.

Highlights:
1 An asymmetric membrane electrode based on phosphorene/MXene heterostructure-textured nanopiezocomposite was fabricated via a polar urea-assisted self-assembly strategy and additive manufacturing of the heterostructure beyond the skin effect.
2 The merits of this novel asymmetric heterostructure-textured electrode and its intrinsic piezoelectricity were detailedly discussed.
3 The stepwise lithiation process of phosphorene was revealed, and the enhanced electrochemical properties of this phosphorene-based nanopiezocomposite textured electrode were verified by the improved cycling stability and kinetics.

Lithium-Ion Charged Polymer Channels Flattening Lithium Metal Anode

Mon, 08 Jan 2024 00:00:00 +0000

The concentration difference in the near-surface region of lithium metal is the main cause of lithium dendrite growth. Resolving this issue will be key to achieving high-performance lithium metal batteries (LMBs). Herein, we construct a lithium nitrate (LiNO₃)-implanted electroactive β phase polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) crystalline polymorph layer (PHL). The electronegatively charged polymer chains attain lithium ions on the surface to form lithium-ion charged channels. These channels act as reservoirs to sustainably release Li ions to recompense the ionic flux of electrolytes, decreasing the growth of lithium dendrites. The stretched molecular channels can also accelerate the transport of Li ions. The combined effects enable a high Coulombic efficiency of 97.0% for 250 cycles in lithium (Li)||copper (Cu) cell and a stable symmetric plating/stripping behavior over 2000 h at 3 mA cm⁻² with ultrahigh Li utilization of 50%. Furthermore, the full cell coupled with PHL-Cu@Li anode and LiFePO₄ cathode exhibits long-term cycle stability with high-capacity retention of 95.9% after 900 cycles. Impressively, the full cell paired with LiNi_0.87Co_0.1Mn_0.03O₂ maintains a discharge capacity of 170.0 mAh g⁻¹ with a capacity retention of 84.3% after 100 cycles even under harsh condition of ultralow N/P ratio of 0.83. This facile strategy will widen the potential application of LiNO₃ in ester-based electrolyte for practical high-voltage LMBs.

Highlights:
1 The LiNO₃-implanted electroactive β phase polyvinylidene fluoride-co-hexafluoropropylene was built as an artificial solid electrolyte interphase layer for dendrite suppression.
2 The electronegatively charged polymer layer can capture Li ion on its surface to form Li-ion charged channels and recompense the ionic flux of electrolytes via continuous supply of Li ion.
3 The modified Li anode achieved a long cycle life over 2000 h under ultrahigh Li utilization of 50% in symmetric cell and worked in full cell for 100 cycles at harsh condition of extremely low N/P of 0.83.

Efficient Polytelluride Anchoring for Ultralong-Life Potassium Storage: Combined Physical Barrier and Chemisorption in Nanogrid-in-Nanofiber

Mon, 08 Jan 2024 00:00:00 +0000

Metal tellurides (MTes) are highly attractive as promising anodes for high-performance potassium-ion batteries. The capacity attenuation of most reported MTe anodes is attributed to their poor electrical conductivity and large volume variation. The evolution mechanisms, dissolution properties, and corresponding manipulation strategies of intermediates (K-polytellurides, K-pTe_x) are rarely mentioned. Herein, we propose a novel structural engineering strategy to confine ultrafine CoTe₂ nanodots in hierarchical nanogrid-in-nanofiber carbon substrates (CoTe₂@NC@NSPCNFs) for smooth immobilization of K-pTe_x and highly reversible conversion of CoTe₂ by manipulating the intense electrochemical reaction process. Various in situ/ex situ techniques and density functional theory calculations have been performed to clarify the formation, transformation, and dissolution of K-pTe_x (K₅Te₃ and K₂Te), as well as verifying the robust physical barrier and the strong chemisorption of K₅Te₃ and K₂Te on S, N co-doped dual-type carbon substrates. Additionally, the hierarchical nanogrid-in-nanofiber nanostructure increases the chemical anchoring sites for K-pTe_x, provides sufficient volume buffer space, and constructs highly interconnected conductive microcircuits, further propelling the battery reaction to new heights (3500 cycles at 2.0 A g⁻¹). Furthermore, the full cells further demonstrate the potential for practical applications. This work provides new insights into manipulating K-pTe_x in the design of ultralong-cycling MTe anodes for advanced PIBs.

Highlights:
1 The hierarchical nanogrid-in-nanofiber-structured dual-type carbon-confined CoTe₂ nanodots (CoTe₂@NC@NSPCNFs) were synthesized via facile templates and an electrospinning approach.
2 Hierarchical nanogrid-in-nanofiber structure effectively suppresses the volume change of CoTe₂ and the shuttle of potassium polytelluride (K-pTex) through robust physical restraint and strong chemisorption.
3 CoTe₂@NC@NSPCNFs hybrid achieves ultralong lifespan potassium-storage performance over 3500 cycles, and the deep mechanisms underlying the evolution, dissolution, and shuttle of K-pTex have been clearly revealed.

Covalent Organic Framework with 3D Ordered Channel and Multi-Functional Groups Endows Zn Anode with Superior Stability

Thu, 04 Jan 2024 00:00:00 +0000

Achieving a highly robust zinc (Zn) metal anode is extremely important for improving the performance of aqueous Zn-ion batteries (AZIBs) for advancing “carbon neutrality” society, which is hampered by the uncontrollable growth of Zn dendrite and severe side reactions including hydrogen evolution reaction, corrosion, and passivation, etc. Herein, an interlayer containing fluorinated zincophilic covalent organic framework with sulfonic acid groups (COF-S-F) is developed on Zn metal (Zn@COF-S-F) as the artificial solid electrolyte interface (SEI). Sulfonic acid group (− SO₃H) in COF-S-F can effectively ameliorate the desolvation process of hydrated Zn ions, and the three-dimensional channel with fluoride group (-F) can provide interconnected channels for the favorable transport of Zn ions with ion-confinement effects, endowing Zn@COF-S-F with dendrite-free morphology and suppressed side reactions. Consequently, Zn@COF-S-F symmetric cell can stably cycle for 1,000 h with low average hysteresis voltage (50.5 mV) at the current density of 1.5 mA cm⁻². Zn@COF-S-F|MnO₂ cell delivers the discharge specific capacity of 206.8 mAh g⁻¹ at the current density of 1.2 A g⁻¹ after 800 cycles with high-capacity retention (87.9%). Enlightening, building artificial SEI on metallic Zn surface with targeted design has been proved as the effective strategy to foster the practical application of high-performance AZIBs.

Highlights:
1 A fluorinated zincophilic covalent organic framework (COF-S-F) with sulfonic acid group (-SO₃H) is prepared on the surface of Zn anode, which promotes the desolvation of hydrated Zn ions and inhibits the side reactions.
2 The highly electronegative -F group in COF-S-F promotes fast and uniform transport of Zn ions along the interconnected channels, which contributes to the uniform electrodeposition process of Zn metal.
3 Zn@COF-S-F symmetric cell achieves a superior stability of 1,000 h and Zn@COF-S-F|MnO₂ cell delivers high specific capacity of 206.8 mAh g⁻¹ at current density of 1.2 A g⁻¹.

ZnO Additive Boosts Charging Speed and Cycling Stability of Electrolytic Zn–Mn Batteries

Thu, 04 Jan 2024 00:00:00 +0000

Electrolytic aqueous zinc-manganese (Zn–Mn) batteries have the advantage of high discharge voltage and high capacity due to two-electron reactions. However, the pitfall of electrolytic Zn–Mn batteries is the sluggish deposition reaction kinetics of manganese oxide during the charge process and short cycle life. We show that, incorporating ZnO electrolyte additive can form a neutral and highly viscous gel-like electrolyte and render a new form of electrolytic Zn–Mn batteries with significantly improved charging capabilities. Specifically, the ZnO gel-like electrolyte activates the zinc sulfate hydroxide hydrate assisted Mn²⁺ deposition reaction and induces phase and structure change of the deposited manganese oxide (Zn₂Mn₃O₈·H₂O nanorods array), resulting in a significant enhancement of the charge capability and discharge efficiency. The charge capacity increases to 2.5 mAh cm⁻² after 1 h constant-voltage charging at 2.0 V vs. Zn/Zn²⁺, and the capacity can retain for up to 2000 cycles with negligible attenuation. This research lays the foundation for the advancement of electrolytic Zn–Mn batteries with enhanced charging capability.

Highlights:
1 Low pH value of electrolyte suppresses the charge capabilities of electrolytic Zn–Mn batteries.
2 Unique solid phase alkaline properties of zinc sulfate hydroxide hydrate endow the electrolytic Zn–Mn batteries with greatly enhanced charge capabilities.
3 The highly active Zn₂Mn₃O₈·H₂O nanorods array deposited during the charge process improve the discharge efficiency and stability of electrolytic Zn–Mn batteries.

Highly Aligned Ternary Nanofiber Matrices Loaded with MXene Expedite Regeneration of Volumetric Muscle Loss

Thu, 04 Jan 2024 00:00:00 +0000

Current therapeutic approaches for volumetric muscle loss (VML) face challenges due to limited graft availability and insufficient bioactivities. To overcome these limitations, tissue-engineered scaffolds have emerged as a promising alternative. In this study, we developed aligned ternary nanofibrous matrices comprised of poly(lactide-co-ε-caprolactone) integrated with collagen and Ti₃C₂T_x MXene nanoparticles (NPs) (PCM matrices), and explored their myogenic potential for skeletal muscle tissue regeneration. The PCM matrices demonstrated favorable physicochemical properties, including structural uniformity, alignment, microporosity, and hydrophilicity. In vitro assays revealed that the PCM matrices promoted cellular behaviors and myogenic differentiation of C2C12 myoblasts. Moreover, in vivo experiments demonstrated enhanced muscle remodeling and recovery in mice treated with PCM matrices following VML injury. Mechanistic insights from next-generation sequencing revealed that MXene NPs facilitated protein and ion availability within PCM matrices, leading to elevated intracellular Ca²⁺ levels in myoblasts through the activation of inducible nitric oxide synthase (iNOS) and serum/glucocorticoid regulated kinase 1 (SGK1), ultimately promoting myogenic differentiation via the mTOR-AKT pathway. Additionally, upregulated iNOS and increased NO^– contributed to myoblast proliferation and fiber fusion, thereby facilitating overall myoblast maturation. These findings underscore the potential of MXene NPs loaded within highly aligned matrices as therapeutic agents to promote skeletal muscle tissue recovery.

Highlights:
1 The aligned ternary nanofibrous matrices composed of poly(lactide-co-ε-caprolactone), collagen, and Ti₃C₂T_x MXene nanoparticles were fabricated (referred as PCM matrices).
2 The aligned PCM matrices exhibited favorable physicochemical properties and excellent cytocompatibility and myogenic properties, which in turn promoted fast regeneration of volumetric muscle loss in vivo.
3 The Ca²⁺ binding of MXene nanoparticles activated inducible nitric oxide synthase and serum/glucocorticoid regulated kinase 1-mediated mTOR-AKT pathway to promote myoblast differentiation and maturation.

Solvation Engineering via Fluorosurfactant Additive Toward Boosted Lithium-Ion Thermoelectrochemical Cells

Yinghong Xu, Zhiwei Li, Langyuan Wu, Hui Dou, Xiaogang Zhang — Thu, 04 Jan 2024 00:00:00 +0000

Lithium-ion thermoelectrochemical cell (LTEC), featuring simultaneous energy conversion and storage, has emerged as promising candidate for low-grade heat harvesting. However, relatively poor thermosensitivity and heat-to-current behavior limit the application of LTECs using LiPF₆ electrolyte. Introducing additives into bulk electrolyte is a reasonable strategy to solve such problem by modifying the solvation structure of electrolyte ions. In this work, we develop a dual-salt electrolyte with fluorosurfactant (FS) additive to achieve high thermopower and durability of LTECs during the conversion of low-grade heat into electricity. The addition of FS induces a unique Li⁺ solvation with the aggregated double anions through a crowded electrolyte environment, resulting in an enhanced mobility kinetics of Li⁺ as well as boosted thermoelectrochemical performances. By coupling optimized electrolyte with graphite electrode, a high thermopower of 13.8 mV K⁻¹ and a normalized output power density of 3.99 mW m^–2 K^–2 as well as an outstanding output energy density of 607.96 J m⁻² can be obtained. These results demonstrate that the optimization of electrolyte by regulating solvation structure will inject new vitality into the construction of thermoelectrochemical devices with attractive properties.

Highlights:
1 Solvation engineering toward dual-salt electrolyte by fluorosurfactant additive is proposed, which implements the stable interface of electrode/electrolyte coupled with fast ion thermodiffusion, improving the durability and capability of lithium-ion thermoelectrochemical cell.
2 By combining the optimized electrolyte with functional electrodes, as-constructed device exhibits high Seebeck coefficient and energy density based on hybrid mechanisms, which can be extended as self-power supply for smart electronics.

Bioinspired Multifunctional Self-Sensing Actuated Gradient Hydrogel for Soft-Hard Robot Remote Interaction

Thu, 04 Jan 2024 00:00:00 +0000

The development of bioinspired gradient hydrogels with self-sensing actuated capabilities for remote interaction with soft-hard robots remains a challenging endeavor. Here, we propose a novel multifunctional self-sensing actuated gradient hydrogel that combines ultrafast actuation and high sensitivity for remote interaction with robotic hand. The gradient network structure, achieved through a wettability difference method involving the rapid precipitation of MoO₂ nanosheets, introduces hydrophilic disparities between two sides within hydrogel. This distinctive approach bestows the hydrogel with ultrafast thermo-responsive actuation (21° s⁻¹) and enhanced photothermal efficiency (increase by 3.7 °C s⁻¹ under 808 nm near-infrared). Moreover, the local cross-linking of sodium alginate with Ca²⁺ endows the hydrogel with programmable deformability and information display capabilities. Additionally, the hydrogel exhibits high sensitivity (gauge factor 3.94 within a wide strain range of 600%), fast response times (140 ms) and good cycling stability. Leveraging these exceptional properties, we incorporate the hydrogel into various soft actuators, including soft gripper, artificial iris, and bioinspired jellyfish, as well as wearable electronics capable of precise human motion and physiological signal detection. Furthermore, through the synergistic combination of remarkable actuation and sensitivity, we realize a self-sensing touch bioinspired tongue. Notably, by employing quantitative analysis of actuation-sensing, we realize remote interaction between soft-hard robot via the Internet of Things. The multifunctional self-sensing actuated gradient hydrogel presented in this study provides a new insight for advanced somatosensory materials, self-feedback intelligent soft robots and human–machine interactions.

Highlights:
1 The bioinspired self-sensing actuated gradient hydrogel was developed by a wettability-based method via precipitation of MoO₂ nanosheets.
2 Self-sensing actuated gradient hydrogel combined ultrafast thermo-responsive actuation (21° s^–1), exceptional photothermal efficiency (3.7 °C s^–1) and high sensing properties (GF = 3.94).
3 The first self-sensing remote interaction system based on gradient hydrogel actuators and robotic hands was constructed.

Hierarchically Structured Nb2O5 Microflowers with Enhanced Capacity and Fast-Charging Capability for Flexible Planar Sodium Ion Micro-Supercapacitors

Thu, 04 Jan 2024 00:00:00 +0000

Planar Na ion micro-supercapacitors (NIMSCs) that offer both high energy density and power density are deemed to a promising class of miniaturized power sources for wearable and portable microelectronics. Nevertheless, the development of NIMSCs are hugely impeded by the low capacity and sluggish Na ion kinetics in the negative electrode. Herein, we demonstrate a novel carbon-coated Nb₂O₅ microflower with a hierarchical structure composed of vertically intercrossed and porous nanosheets, boosting Na ion storage performance. The unique structural merits, including uniform carbon coating, ultrathin nanosheets and abundant pores, endow the Nb₂O₅ microflower with highly reversible Na ion storage capacity of 245 mAh g⁻¹ at 0.25 C and excellent rate capability. Benefiting from high capacity and fast charging of Nb₂O₅ microflower, the planar NIMSCs consisted of Nb₂O₅ negative electrode and activated carbon positive electrode deliver high areal energy density of 60.7 μWh cm⁻², considerable voltage window of 3.5 V and extraordinary cyclability. Therefore, this work exploits a structural design strategy towards electrode materials for application in NIMSCs, holding great promise for flexible microelectronics.

Highlights:
1 Hierarchically structured Nb₂O₅ microflowers consiste of porous and ultrathin nanosheets.
2 Nb₂O₅ microflowers exhibit enhanced capacity and rate performance boosting Na ion storage.
3 Planar NIMSCs with charge and kinetics matching show superior areal capacitance and lifespan.

Tracking Regulatory Mechanism of Trace Fe on Graphene Electromagnetic Wave Absorption

Thu, 04 Jan 2024 00:00:00 +0000

Polarization and conductance losses are the fundamental dielectric attenuation mechanisms for graphene-based absorbers, but it is not fully understood in revealing the loss mechanism of affect graphene itself. For the first time, the reduced graphene oxide (RGO) based absorbers are developed with regulatory absorption properties and the absorption mechanism of RGO is mainly originated from the carrier injection behavior of trace metal Fe nanosheets on graphene. Accordingly, the minimum reflection loss (RL_min) of Fe/RGO-2 composite reaches − 53.38 dB (2.45 mm), and the effective absorption bandwidth achieves 7.52 GHz (2.62 mm) with lower filling loading of 2 wt%. Using off-axis electron hologram testing combined with simulation calculation and carrier transport property experiments, we demonstrate here the carrier injection behavior from Fe to graphene at the interface and the induced charge accumulation and rearrangement, resulting in the increased interfacial and dipole polarization and the conductance loss. This work has confirmed that regulating the dielectric property of graphene itself by adding trace metals can not only ensure good impedance matching, but also fully exploit the dielectric loss ability of graphene at low filler content, which opens up an efficient way for designing lightweight absorbers and may be extended to other types materials.

Highlights:
1 A carrier injection strategy is firstly proposed by designing Fe/reduced graphene oxide (RGO) heterogeneous interfacial material for giving full play to the dielectric dispersion properties of graphene.
2 The electromagnetic wave absorption mechanisms mainly include enhanced conductance loss, dipole polarization and interfacial polarization.
3 Outstanding reflection loss value (− 53.38 dB, 2.45 mm) and broadband wave absorption (7.52 GHz with only 2 wt% filling) of Fe/RGO composite were acquired, which is superior to single-component graphene.

Diphylleia Grayi-Inspired Intelligent Temperature-Responsive Transparent Nanofiber Membranes

Thu, 04 Jan 2024 00:00:00 +0000

Nanofiber membranes (NFMs) have become attractive candidates for next-generation flexible transparent materials due to their exceptional flexibility and breathability. However, improving the transmittance of NFMs is a great challenge due to the enormous reflection and incredibly poor transmission generated by the nanofiber-air interface. In this research, we report a general strategy for the preparation of flexible temperature-responsive transparent (TRT) membranes, which achieves a rapid transformation of NFMs from opaque to highly transparent under a narrow temperature window. In this process, the phase change material eicosane is coated on the surface of the polyurethane nanofibers by electrospray technology. When the temperature rises to 37 °C, eicosane rapidly completes the phase transition and establishes the light transmission path between the nanofibers, preventing light loss from reflection at the nanofiber-air interface. The resulting TRT membrane exhibits high transmittance (> 90%), and fast response (5 s). This study achieves the first TRT transition of NFMs, offering a general strategy for building highly transparent nanofiber materials, shaping the future of next-generation intelligent temperature monitoring, anti-counterfeiting measures, and other high-performance devices.

Highlights:
1 Temperature-responsive transparent nanofiber membranes were successfully fabricated using a straightforward and widely applicable method.
2 The temperature-responsive nanofiber membranes exhibit a lower reaction temperature (~ 37 °C) and higher transmittance (> 90%).
3 The prepared temperature-responsive transparent nanofiber membranes exhibited a short response temperature time (~ 5 s), and remarkable stability

Precisely Control Relationship between Sulfur Vacancy and H Absorption for Boosting Hydrogen Evolution Reaction

Jing Jin, Xinyao Wang, Yang Hu, Zhuang Zhang, Hongbo Liu, Jie Yin, Pinxian Xi — Tue, 02 Jan 2024 00:00:00 +0000

Effective and robust catalyst is the core of water splitting to produce hydrogen. Here, we report an anionic etching method to tailor the sulfur vacancy (V_S) of NiS₂ to further enhance the electrocatalytic performance for hydrogen evolution reaction (HER). With the V_S concentration change from 2.4% to 8.5%, the H* adsorption strength on S sites changed and NiS₂-V_S 5.9% shows the most optimized H* adsorption for HER with an ultralow onset potential (68 mV) and has long-term stability for 100 h in 1 M KOH media. In situ attenuated-total-reflection Fourier transform infrared spectroscopy (ATR-FTIRS) measurements are usually used to monitor the adsorption of intermediates. The S- H* peak of the NiS₂-V_S 5.9% appears at a very low voltage, which is favorable for the HER in alkaline media. Density functional theory calculations also demonstrate the NiS₂-V_S 5.9% has the optimal |ΔG_H*| of 0.17 eV. This work offers a simple and promising pathway to enhance catalytic activity via precise vacancies strategy.

Highlights:
1 The Ar plasma etching strategy was introduced to homogeneously distributed S-vacancies (VS) into the NiS₂ nanosheets (NiS₂-VS).
2 Build the relationship between sulfur vacancy and H absorption and find that NiS₂-VS 5.9% performs outstanding hydrogen evolution reaction performance and remarkable stability.

Proof of Aerobically Autoxidized Self-Charge Concept Based on Single Catechol-Enriched Carbon Cathode Material

Wed, 20 Dec 2023 00:00:00 +0000

The self-charging concept has drawn considerable attention due to its excellent ability to achieve environmental energy harvesting, conversion and storage without an external power supply. However, most self-charging designs assembled by multiple energy harvesting, conversion and storage materials increase the energy transfer loss; the environmental energy supply is generally limited by climate and meteorological conditions, hindering the potential application of these self-powered devices to be available at all times. Based on aerobic autoxidation of catechol, which is similar to the electrochemical oxidation of the catechol groups on the carbon materials under an electrical charge, we proposed an air-breathing chemical self-charge concept based on the aerobic autoxidation of catechol groups on oxygen-enriched carbon materials to ortho-quinone groups. Energy harvesting, conversion and storage functions could be integrated on a single carbon material to avoid the energy transfer loss among the different materials. Moreover, the assembled Cu/oxygen-enriched carbon battery confirmed the feasibility of the air-oxidation self-charging/electrical discharging mechanism for potential applications. This air-breathing chemical self-charge concept could facilitate the exploration of high-efficiency sustainable air self-charging devices.

Highlights:
1 An air-breathing chemical self-charge concept of oxygen-enriched carbon cathode.
2 The oxygen-enriched carbon material with abundant catechol groups.
3 Rapid air-oxidation chemical self-charge of catechol groups.

Correction to: Green Vertical-Cavity Surface-Emitting Lasers Based on InGaN Quantum Dots and Short Cavity

Wed, 20 Dec 2023 00:00:00 +0000

Room temperature low threshold lasing of green GaN-based vertical cavity surface emitting laser (VCSEL) was demonstrated under continuous wave (CW) operation. By using self-formed InGaN quantum dots (QDs) as the active region, the VCSEL emitting at 524.0 nm has a threshold current density of 51.97 A cm⁻², the lowest ever reported. The QD epitaxial wafer featured with a high IQE of 69.94% and the δ-function-like density of states plays an important role in achieving low threshold current. Besides, a short cavity of the device (~ 4.0 λ) is vital to enhance the spontaneous emission coupling factor to 0.094, increase the gain coefficient factor, and decrease the optical loss. To improve heat dissipation, AlN layer was used as the current confinement layer and electroplated copper plate was used to replace metal bonding. The results provide important guidance to achieving high performance GaN-based VCSELs.

Highlights:
1 Continuous-wave green vertical-cavity surface-emitting lasers based on self-formed quantum dots were realized with the lowest threshold current density of 51.97 A cm⁻².
2 A short cavity (~4.0 λ, where λ is the wavelength in the media) was adopted to enhance the interaction between spontaneous emission and lasing mode, with a big coupling factor up to 0.094.
3 AlN current confinement layer and the electroplated supporting copper plate were utilized to improve heat dissipation, with a low thermal resistance of 842 K W⁻¹.

Two-Dimensional Cr5Te8@Graphite Heterostructure for Efficient Electromagnetic Microwave Absorption

Wed, 20 Dec 2023 00:00:00 +0000

Two-dimensional (2D) transition metal chalcogenides (TMCs) hold great promise as novel microwave absorption materials owing to their interlayer interactions and unique magnetoelectric properties. However, overcoming the impedance mismatch at the low loading is still a challenge for TMCs due to the restricted loss pathways caused by their high-density characteristic. Here, an interface engineering based on the heterostructure of 2D Cr₅Te₈ and graphite is in situ constructed via a one-step chemical vapor deposit to modulate impedance matching and introduce multiple attenuation mechanisms. Intriguingly, the Cr₅Te₈@EG (ECT) heterostructure exhibits a minimum reflection loss of up to − 57.6 dB at 15.4 GHz with a thin thickness of only 1.4 mm under a low filling rate of 10%. The density functional theory calculations confirm that the splendid performance of ECT heterostructure primarily derives from charge redistribution at the abundant intimate interfaces, thereby reinforcing interfacial polarization loss. Furthermore, the ECT coating displays a remarkable radar cross section reduction of 31.9 dB m², demonstrating a great radar microwave scattering ability. This work sheds light on the interfacial coupled stimulus response mechanism of TMC-based heterogeneous structures and provides a feasible strategy to manipulate high-quality TMCs for excellent microwave absorbers.

Highlights:
1 A Cr₅Te₈@expanded graphite heterostructure is fabricated by chemical vapor deposition, exhibiting remarkable microwave absorption performance with a minimum reflection loss of up to − 57.6 dB at a thin thickness of only 1.4 mm under a low filling rate of 10%.
2 Density functional theory calculations deeply reveal the polarization loss mechanism triggered by heterogeneous interfaces.
3 The heterostructure coating displays a remarkable radar cross section reduction of 31.9 dB m², demonstrating a great electromagnetic microwave scattering ability and radar stealth capability.

Ultraviolet-Irradiated All-Organic Nanocomposites with Polymer Dots for High-Temperature Capacitive Energy Storage

Wed, 20 Dec 2023 00:00:00 +0000

Polymer dielectrics capable of operating efficiently at high electric fields and elevated temperatures are urgently demanded by next-generation electronics and electrical power systems. While inorganic fillers have been extensively utilized to improved high-temperature capacitive performance of dielectric polymers, the presence of thermodynamically incompatible organic and inorganic components may lead to concern about the long-term stability and also complicate film processing. Herein, zero-dimensional polymer dots with high electron affinity are introduced into photoactive allyl-containing poly(aryl ether sulfone) to form the all-organic polymer composites for high-temperature capacitive energy storage. Upon ultraviolet irradiation, the crosslinked polymer composites with polymer dots are efficient in suppressing electrical conduction at high electric fields and elevated temperatures, which significantly reduces the high-field energy loss of the composites at 200 °C. Accordingly, the ultraviolet-irradiated composite film exhibits a discharged energy density of 4.2 J cm⁻³ at 200 °C. Along with outstanding cyclic stability of capacitive performance at 200 °C, this work provides a promising class of dielectric materials for robust high-performance all-organic dielectric nanocomposites.

Highlights:
1 All-organic polymer composites for high-temperature capacitive energy storage.
2 Zero-dimensional polymer dots with high electron affinity are used as fillers.
3 Deep charge traps from UV-irradiated films reduce the high-field conduction loss.

Highly Thermally Conductive and Structurally Ultra-Stable Graphitic Films with Seamless Heterointerfaces for Extreme Thermal Management

Tue, 19 Dec 2023 00:00:00 +0000

Highly thermally conductive graphitic film (GF) materials have become a competitive solution for the thermal management of high-power electronic devices. However, their catastrophic structural failure under extreme alternating thermal/cold shock poses a significant challenge to reliability and safety. Here, we present the first investigation into the structural failure mechanism of GF during cyclic liquid nitrogen shocks (LNS), which reveals a bubbling process characterized by “permeation-diffusion-deformation” phenomenon. To overcome this long-standing structural weakness, a novel metal-nanoarmor strategy is proposed to construct a Cu-modified graphitic film (GF@Cu) with seamless heterointerface. This well-designed interface ensures superior structural stability for GF@Cu after hundreds of LNS cycles from 77 to 300 K. Moreover, GF@Cu maintains high thermal conductivity up to 1088 W m⁻¹ K⁻¹ with degradation of less than 5% even after 150 LNS cycles, superior to that of pure GF (50% degradation). Our work not only offers an opportunity to improve the robustness of graphitic films by the rational structural design but also facilitates the applications of thermally conductive carbon-based materials for future extreme thermal management in complex aerospace electronics.

Highlights:
1 Presenting the first investigation into the structurally bubbling-failure mechanism of graphitic film during cyclic liquid nitrogen shocks.
2 Proposing an innovative design about seamless heterointerface constructing a Cu-modified structure.
3 Inventing a new ultra-stable species of highly thermally conductive films to inspire new techniques for efficient and extreme thermal management.

Self-Assembly of Binderless MXene Aerogel for Multiple-Scenario and Responsive Phase Change Composites with Ultrahigh Thermal Energy Storage Density and Exceptional Electromagnetic Interference Shielding

Mon, 18 Dec 2023 00:00:00 +0000

The severe dependence of traditional phase change materials (PCMs) on the temperature-response and lattice deficiencies in versatility cannot satisfy demand for using such materials in complex application scenarios. Here, we introduced metal ions to induce the self-assembly of MXene nanosheets and achieve their ordered arrangement by combining suction filtration and rapid freezing. Subsequently, a series of MXene/ K⁺/paraffin wax (PW) phase change composites (PCCs) were obtained via vacuum impregnation in molten PW. The prepared MXene-based PCCs showed versatile applications from macroscale technologies, successfully transforming solar, electric, and magnetic energy into thermal energy stored as latent heat in the PCCs. Moreover, due to the absence of binder in the MXene-based aerogel, MK3@PW exhibits a prime solar–thermal conversion efficiency (98.4%). Notably, MK3@PW can further convert the collected heat energy into electric energy through thermoelectric equipment and realize favorable solar–thermal–electric conversion (producing 206 mV of voltage with light radiation intensity of 200 mw cm⁻²). An excellent Joule heat performance (reaching 105 °C with an input voltage of 2.5 V) and responsive magnetic–thermal conversion behavior (a charging time of 11.8 s can achieve a thermal insulation effect of 285 s) for contactless thermotherapy were also demonstrated by the MK3@PW. Specifically, as a result of the ordered arrangement of MXene nanosheet self-assembly induced by potassium ions, MK3@PW PCC exhibits a higher electromagnetic shielding efficiency value (57.7 dB) than pure MXene aerogel/PW PCC (29.8 dB) with the same MXene mass. This work presents an opportunity for the multi-scene response and practical application of PCMs that satisfy demand of next-generation multifunctional PCCs.

Highlights:
1 This work proposes a tactic for improving the efficiency of thermal energy conversion and expanding the application scenarios of phase change materials by constructing non-binder and oriented MXene-K⁺ aerogel.
2 The prepared phase change composites (PCCs) can rapidly transform solar, electric, magnetic energy into latent heat for keeping warm, power generation, and thermal physiotherapy.
3 Owing to the suggested tactic, the prepared PCCs achieves ultrahigh energy storage density and realize 99.9998% electromagnetic wave energy attenuation.

Moisture-Electric–Moisture-Sensitive Heterostructure Triggered Proton Hopping for Quality-Enhancing Moist-Electric Generator

Mon, 18 Dec 2023 00:00:00 +0000

Moisture-enabled electricity (ME) is a method of converting the potential energy of water in the external environment into electrical energy through the interaction of functional materials with water molecules and can be directly applied to energy harvesting and signal expression. However, ME can be unreliable in numerous applications due to its sluggish response to moisture, thus sacrificing the value of fast energy harvesting and highly accurate information representation. Here, by constructing a moisture-electric–moisture-sensitive (ME-MS) heterostructure, we develop an efficient ME generator with ultra-fast electric response to moisture achieved by triggering Grotthuss protons hopping in the sensitized ZnO, which modulates the heterostructure built-in interfacial potential, enables quick response (0.435 s), an unprecedented ultra-fast response rate of 972.4 mV s⁻¹, and a durable electrical signal output for 8 h without any attenuation. Our research provides an efficient way to generate electricity and important insight for a deeper understanding of the mechanisms of moisture-generated carrier migration in ME generator, which has a more comprehensive working scene and can serve as a typical model for human health monitoring and smart medical electronics design.

Highlights:
1 An efficient moist-electric generator with ultra-fast electric response to moisture is achieved by triggering Grotthuss protons hopping in the moisture-electric–moisture-sensitive heterostructure.
2 The moist-electric generator produces a quick response (0.435 s), an unprecedented ultra-fast response rate of 972.4 mV s⁻¹ to alternating moisture stimulation and stable output for 8 h.
3 An obstructive sleep apnea hypoventilation syndrome diagnostic system based on a moist-electric generator was developed to monitor hypopnea and apnea in real time and successfully diagnose them with early warning.

Enhanced Redox Electrocatalysis in High-Entropy Perovskite Fluorides by Tailoring d–p Hybridization

Mon, 18 Dec 2023 00:00:00 +0000

High-entropy catalysts featuring exceptional properties are, in no doubt, playing an increasingly significant role in aprotic lithium-oxygen batteries. Despite extensive effort devoted to tracing the origin of their unparalleled performance, the relationships between multiple active sites and reaction intermediates are still obscure. Here, enlightened by theoretical screening, we tailor a high-entropy perovskite fluoride (KCoMnNiMgZnF₃-HEC) with various active sites to overcome the limitations of conventional catalysts in redox process. The entropy effect modulates the d-band center and d orbital occupancy of active centers, which optimizes the d–p hybridization between catalytic sites and key intermediates, enabling a moderate adsorption of LiO₂ and thus reinforcing the reaction kinetics. As a result, the Li–O₂ battery with KCoMnNiMgZnF₃-HEC catalyst delivers a minimal discharge/charge polarization and long-term cycle stability, preceding majority of traditional catalysts reported. These encouraging results provide inspiring insights into the electron manipulation and d orbital structure optimization for advanced electrocatalyst.

Highlights:
1 The tailored KCoMnNiMgZnF₃-HEC cathode delivers extremely high discharge capacity (22,104 mAh g⁻¹), outstanding long-term cyclability (over 500 h), preceding majority of traditional catalysts reported.
2 Entropy effect of multiple sites in KCoMnNiMgZnF₃-HEC engenders appropriate regulation of 3d orbital structure, leading to a moderate hybridization with the p orbital of key intermediate.
3 The homogeneous nucleation of Li₂O₂ is achieved on multiple cation site, contributing to effective mass transfer at the three-phase interface, and thus, the reversibility of O₂/Li₂O₂ conversion.

Engineering Nano/Microscale Chiral Self-Assembly in 3D Printed Constructs

Mon, 18 Dec 2023 00:00:00 +0000

Helical hierarchy found in biomolecules like cellulose, chitin, and collagen underpins the remarkable mechanical strength and vibrant colors observed in living organisms. This study advances the integration of helical/chiral assembly and 3D printing technology, providing precise spatial control over chiral nano/microstructures of rod-shaped colloidal nanoparticles in intricate geometries. We designed reactive chiral inks based on cellulose nanocrystal (CNC) suspensions and acrylamide monomers, enabling the chiral assembly at nano/microscale, beyond the resolution seen in printed materials. We employed a range of complementary techniques including Orthogonal Superposition rheometry and in situ rheo-optic measurements under steady shear rate conditions. These techniques help us to understand the nature of the nonlinear flow behavior of the chiral inks, and directly probe the flow-induced microstructural dynamics and phase transitions at constant shear rates, as well as their post-flow relaxation. Furthermore, we analyzed the photo-curing process to identify key parameters affecting gelation kinetics and structural integrity of the printed object within the supporting bath. These insights into the interplay between the chiral inks self-assembly dynamics, 3D printing flow kinematics and photo-polymerization kinetics provide a roadmap to direct the out-of-equilibrium arrangement of CNC particles in the 3D printed filaments, ranging from uniform nematic to 3D concentric chiral structures with controlled pitch length, as well as random orientation of chiral domains. Our biomimetic approach can pave the way for the creation of materials with superior mechanical properties or programable photonic responses that arise from 3D nano/microstructure and can be translated into larger scale 3D printed designs.

Highlights:
1 To precisely engineer complex helical hierarchies at nano/microscales, reactive inks with chiral nematic anisotropy are designed for 3D printing.
2 The phase transformations and chiral evolution in response to parallel and orthogonal shear forces are meticulously investigated to finely adjust the 3D printing parameters for programming oriented chiral assemblies.
3 The interplay between chiral relaxation dynamics and photo-polymerization kinetics is finely tuned to enable well-controlled chiral reformation, while simultaneously ensuring high print quality.

Exploring the Cation Regulation Mechanism for Interfacial Water Involved in the Hydrogen Evolution Reaction by In Situ Raman Spectroscopy

Mon, 18 Dec 2023 00:00:00 +0000

Interfacial water molecules are the most important participants in the hydrogen evolution reaction (HER). Hence, understanding the behavior and role that interfacial water plays will ultimately reveal the HER mechanism. Unfortunately, investigating interfacial water is extremely challenging owing to the interference caused by bulk water molecules and complexity of the interfacial environment. Here, the behaviors of interfacial water in different cationic electrolytes on Pd surfaces were investigated by the electrochemistry, in situ core–shell nanostructure enhanced Raman spectroscopy and theoretical simulation techniques. Direct spectral evidence reveals a red shift in the frequency and a decrease in the intensity of interfacial water as the potential is shifted in the positively direction. When comparing the different cation electrolyte systems at a given potential, the frequency of the interfacial water peak increases in the specified order: Li⁺ < Na⁺ < K⁺ < Ca²⁺ < Sr²⁺. The structure of interfacial water was optimized by adjusting the radius, valence, and concentration of cation to form the two-H down structure. This unique interfacial water structure will improve the charge transfer efficiency between the water and electrode further enhancing the HER performance. Therefore, local cation tuning strategies can be used to improve the HER performance by optimizing the interfacial water structure.

Highlights:
1 In situ Raman spectroscopy study of the cation regulation for interfacial water on Au@Pd core–shell nanoparticle surface during hydrogen evolution reaction process.
2 Direct spectral evidence reveals new strategies to optimize the structure of interfacial water by the adjusting of radius and valence of the cation in the electrolyte.
3 The optimized structure of interfacial water will improve the charge transfer efficiency between the water and electrode increasing the performance of the hydrogen evolution reaction.

Strongly Coupled Ag/Sn–SnO2 Nanosheets Toward CO2 Electroreduction to Pure HCOOH Solutions at Ampere-Level Current

Wed, 13 Dec 2023 00:00:00 +0000

Electrocatalytic reduction of CO₂ converts intermittent renewable electricity into value-added liquid products with an enticing prospect, but its practical application is hampered due to the lack of high-performance electrocatalysts. Herein, we elaborately design and develop strongly coupled nanosheets composed of Ag nanoparticles and Sn–SnO₂ grains, designated as Ag/Sn–SnO₂ nanosheets (NSs), which possess optimized electronic structure, high electrical conductivity, and more accessible sites. As a result, such a catalyst exhibits unprecedented catalytic performance toward CO₂-to-formate conversion with near-unity faradaic efficiency (≥ 90%), ultrahigh partial current density (2,000 mA cm⁻²), and superior long-term stability (200 mA cm⁻², 200 h), surpassing the reported catalysts of CO₂ electroreduction to formate. Additionally, in situ attenuated total reflection-infrared spectra combined with theoretical calculations revealed that electron-enriched Sn sites on Ag/Sn–SnO₂ NSs not only promote the formation of *OCHO and alleviate the energy barriers of *OCHO to *HCOOH, but also impede the desorption of H*. Notably, the Ag/Sn–SnO₂ NSs as the cathode in a membrane electrode assembly with porous solid electrolyte layer reactor can continuously produce ~ 0.12 M pure HCOOH solution at 100 mA cm⁻² over 200 h. This work may inspire further development of advanced electrocatalysts and innovative device systems for promoting practical application of producing liquid fuels from CO₂.

Highlights:
1 The strongly coupled Ag/Sn–SnO₂ nanosheets (NSs) were prepared via a versatile electrochemical template strategy, and the generated electron-enriched Sn sites promote the formation of *OCHO and alleviate the energy barriers of *OCHO to *HCOOH.
2 Ag/Sn–SnO₂ NSs afford a superior activity toward CO₂ electroreduction with current densities up to 2000 mA cm^‒2 and near-unity selectivity for formate production.
3 Ag/Sn–SnO₂ NSs as the cathode in a membrane electrode assembly with porous solid electrolyte reactor enable the direct production of ~ 0.12 M pure HCOOH solution for 200 h.

Mitigating Lattice Distortion of High-Voltage LiCoO2 via Core-Shell Structure Induced by Cationic Heterogeneous Co-Doping for Lithium-Ion Batteries

Mon, 11 Dec 2023 00:00:00 +0000

Inactive elemental doping is commonly used to improve the structural stability of high-voltage layered transition-metal oxide cathodes. However, the one-step co-doping strategy usually results in small grain size since the low diffusivity ions such as Ti⁴⁺ will be concentrated on grain boundaries, which hinders the grain growth. In order to synthesize large single-crystal layered oxide cathodes, considering the different diffusivities of different dopant ions, we propose a simple two-step multi-element co-doping strategy to fabricate core–shell structured LiCoO₂ (CS-LCO). In the current work, the high-diffusivity Al³⁺/Mg²⁺ ions occupy the core of single-crystal grain while the low diffusivity Ti⁴⁺ ions enrich the shell layer. The Ti⁴⁺-enriched shell layer (~ 12 nm) with Co/Ti substitution and stronger Ti–O bond gives rise to less oxygen ligand holes. In-situ XRD demonstrates the constrained contraction of c-axis lattice parameter and mitigated structural distortion. Under a high upper cut-off voltage of 4.6 V, the single-crystal CS-LCO maintains a reversible capacity of 159.8 mAh g⁻¹ with a good retention of ~ 89% after 300 cycles, and reaches a high specific capacity of 163.8 mAh g⁻¹ at 5C. The proposed strategy can be extended to other pairs of low- (Zr⁴⁺, Ta⁵⁺, and W⁶⁺, etc.) and high-diffusivity cations (Zn²⁺, Ni²⁺, and Fe³⁺, etc.) for rational design of advanced layered oxide core–shell structured cathodes for lithium-ion batteries.

Highlights:
1 A simple two-step multi-element co-doping strategy is proposed to fabricate core-shell structured LiCoO₂ based on the different diffusivities of dopant ions.
2 The high diffusivity Al³⁺/Mg²⁺ ions occupy the core of single-crystal grain while the low diffusivity Ti⁴⁺ ions enrich the shell layer.
3 In-situ XRD demonstrates the mitigated structural distortion under a high cut-off voltage of 4.6 V, resulting in a significantly improved cycling stability.

Chemical Scissors Tailored Nano-Tellurium with High-Entropy Morphology for Efficient Foam-Hydrogel-Based Solar Photothermal Evaporators

Fri, 08 Dec 2023 00:00:00 +0000

The development of tellurium (Te)-based semiconductor nanomaterials for efficient light-to-heat conversion may offer an effective means of harvesting sunlight to address global energy concerns. However, the nanosized Te (nano-Te) materials reported to date suffer from a series of drawbacks, including limited light absorption and a lack of surface structures. Herein, we report the preparation of nano-Te by electrochemical exfoliation using an electrolyzable room-temperature ionic liquid. Anions, cations, and their corresponding electrolytic products acting as chemical scissors can precisely intercalate and functionalize bulk Te. The resulting nano-Te has high morphological entropy, rich surface functional groups, and broad light absorption. We also constructed foam hydrogels based on poly (vinyl alcohol)/nano-Te, which achieved an evaporation rate and energy efficiency of 4.11 kg m⁻² h⁻¹ and 128%, respectively, under 1 sun irradiation. Furthermore, the evaporation rate was maintained in the range 2.5–3.0 kg m⁻² h⁻¹ outdoors under 0.5–1.0 sun, providing highly efficient evaporation under low light conditions.

Highlights:
1 Precise exfoliation and modification of nano-Tellurium was realized by adopting a room-temperature ionic liquid as the electrolyte.
2 Nano-Tellurium with high-entropy morphology can offer greater solar absorption and more kinds of surface chemical groups, giving rise to superior photothermal properties.
3 Nano-Tellurium-poly(vinyl alcohol)-based photothermal foam hydrogels, with high compressibility, excellent water transport rate and low evaporation enthalpy of water, combined with a new heat-supply model, achieve an evaporation rate of 4.11 kg m⁻² h⁻¹ with energy efficiencies up to 128% under 1 sun irradiation, which are the highest values for semiconductor-based nanocomposites reported so far.

Intramolecular Hydrogen Bond Improved Durability and Kinetics for Zinc-Organic Batteries

Fri, 08 Dec 2023 00:00:00 +0000

Organic compounds have the advantages of green sustainability and high designability, but their high solubility leads to poor durability of zinc-organic batteries. Herein, a high-performance quinone-based polymer (H-PNADBQ) material is designed by introducing an intramolecular hydrogen bonding (HB) strategy. The intramolecular HB (C=O⋯N–H) is formed in the reaction of 1,4-benzoquinone and 1,5-naphthalene diamine, which efficiently reduces the H-PNADBQ solubility and enhances its charge transfer in theory. In situ ultraviolet–visible analysis further reveals the insolubility of H-PNADBQ during the electrochemical cycles, enabling high durability at different current densities. Specifically, the H-PNADBQ electrode with high loading (10 mg cm⁻²) performs a long cycling life at 125 mA g⁻¹ (> 290 cycles). The H-PNADBQ also shows high rate capability (137.1 mAh g⁻¹ at 25 A g⁻¹) due to significantly improved kinetics inducted by intramolecular HB. This work provides an efficient approach toward insoluble organic electrode materials.

Highlights:
1 Intramolecular hydrogen bond regulation is proposed to improve the quinone-based polymer (H-PNADBQ) solubility, conductivity, and kinetics.
2 Intramolecular hydrogen bonds reduce molecular polarization and increase π conjugation level, thereby suppressing the dissolution of the H-PNADBQ and accelerating reaction kinetics of H⁺/Zn²⁺ uptake/removal.
3 The H-PNADBQ electrodes exhibit excellent durability with high loading of 5 mg cm⁻² and 10 mg cm⁻², as well as high rate capability (137.1 mAh g⁻¹ at 25 A g⁻¹).

Unraveling the Fundamental Mechanism of Interface Conductive Network Influence on the Fast-Charging Performance of SiO-Based Anode for Lithium-Ion Batteries

Mon, 04 Dec 2023 00:00:00 +0000

Progress in the fast charging of high-capacity silicon monoxide (SiO)-based anode is currently hindered by insufficient conductivity and notable volume expansion. The construction of an interface conductive network effectively addresses the aforementioned problems; however, the impact of its quality on lithium-ion transfer and structure durability is yet to be explored. Herein, the influence of an interface conductive network on ionic transport and mechanical stability under fast charging is explored for the first time. 2D modeling simulation and Cryo-transmission electron microscopy precisely reveal the mitigation of interface polarization owing to a higher fraction of conductive inorganic species formation in bilayer solid electrolyte interphase is mainly responsible for a linear decrease in ionic diffusion energy barrier. Furthermore, atomic force microscopy and Raman shift exhibit substantial stress dissipation generated by a complete conductive network, which is critical to the linear reduction of electrode residual stress. This study provides insights into the rational design of optimized interface SiO-based anodes with reinforced fast-charging performance.

Highlights:
1 Influence of interface conductive network on ionic transport and mechanical stability under fast charging is explored for the first time.
2 The mitigation of interface polarization is precisely revealed by the combination of 2D modeling simulation and Cryo-TEM observation, which can be attributed to a higher fraction formation of conductive inorganic species in bilayer SEI, and primarily contributes to a linear decrease in ionic diffusion energy barrier.
3 The improved stress dissipation presented by AFM and Raman shift is critical for the linear reduction in electrode residual stress and thickness swelling.

Metal–Organic Gel Leading to Customized Magnetic-Coupling Engineering in Carbon Aerogels for Excellent Radar Stealth and Thermal Insulation Performances

Mon, 04 Dec 2023 00:00:00 +0000

Metal–organic gel (MOG) derived composites are promising multi-functional materials due to their alterable composition, identifiable chemical homogeneity, tunable shape, and porous structure. Herein, stable metal–organic hydrogels are prepared by regulating the complexation effect, solution polarity and curing speed. Meanwhile, collagen peptide is used to facilitate the fabrication of a porous aerogel with excellent physical properties as well as the homogeneous dispersion of magnetic particles during calcination. Subsequently, two kinds of heterometallic magnetic coupling systems are obtained through the application of Kirkendall effect. FeCo/nitrogen-doped carbon (NC) aerogel demonstrates an ultra-strong microwave absorption of − 85 dB at an ultra-low loading of 5%. After reducing the time taken by atom shifting, a FeCo/Fe₃O₄/NC aerogel containing virus-shaped particles is obtained, which achieves an ultra-broad absorption of 7.44 GHz at an ultra-thin thickness of 1.59 mm due to the coupling effect offered by dual-soft-magnetic particles. Furthermore, both aerogels show excellent thermal insulation property, and their outstanding radar stealth performances in J-20 aircraft are confirmed by computer simulation technology. The formation mechanism of MOG is also discussed along with the thermal insulation and electromagnetic wave absorption mechanism of the aerogels, which will enable the development and application of novel and lightweight stealth coatings.

Highlights:
1 Fe³⁺, Co²⁺, H₃BTC, and collagen peptide are used to achieve a one-step assembly of stable FeCo-MOG/CP by manipulating the complexation effect and solution polarity.
2 By optimizing pyrolysis, two kinds of nitrogen-doped carbon aerogels loaded with virus-shaped and nanospherical magnetic particles are obtained.
3 FeCo/Fe₃O₄/NC and FeCo/NC aerogels exhibit excellent electromagnetic wave absorbing and radar stealth performances.

Internal Polarization Field Induced Hydroxyl Spillover Effect for Industrial Water Splitting Electrolyzers

Jingyi Xie, Fuli Wang, Yanan Zhou, Yiwen Dong, Yongming Chai, Bin Dong — Thu, 30 Nov 2023 00:00:00 +0000

The formation of multiple oxygen intermediates supporting efficient oxygen evolution reaction (OER) are affinitive with hydroxyl adsorption. However, ability of the catalyst to capture hydroxyl and maintain the continuous supply at active sits remains a tremendous challenge. Herein, an affordable Ni₂P/FeP₂ heterostructure is presented to form the internal polarization field (IPF), arising hydroxyl spillover (HOSo) during OER. Facilitated by IPF, the oriented HOSo from FeP₂ to Ni₂P can activate the Ni site with a new hydroxyl transmission channel and build the optimized reaction path of oxygen intermediates for lower adsorption energy, boosting the OER activity (242 mV vs. RHE at 100 mA cm^–2) for least 100 h. More interestingly, for the anion exchange membrane water electrolyzer (AEMWE) with low concentration electrolyte, the advantage of HOSo effect is significantly amplified, delivering 1 A cm^–2 at a low cell voltage of 1.88 V with excellent stability for over 50 h.

Highlights:
1 Analyzed the function of internal polarization field in Ni₂P/FeP₂ via hydroxyl spillover effect.
2 From theoretical design to experimental verification, to optimize adsorption energy of oxygen intermediates on Ni active site, and further boost the xygen evolution reaction process.
3 A hydroxyl spillover effect driven by internal polarization field in Ni₂P/FeP₂ can be amplified in low concentration alkaline electrolyte environment, and facilitate the application in anion exchange membrane water electrolyzer systems.

Flexible and Robust Functionalized Boron Nitride/Poly(p-Phenylene Benzobisoxazole) Nanocomposite Paper with High Thermal Conductivity and Outstanding Electrical Insulation

Lin Tang, Kunpeng Ruan, Xi Liu, Yusheng Tang, Yali Zhang, Junwei Gu — Thu, 30 Nov 2023 00:00:00 +0000

With the rapid development of 5G information technology, thermal conductivity/dissipation problems of highly integrated electronic devices and electrical equipment are becoming prominent. In this work, “high-temperature solid-phase & diazonium salt decomposition” method is carried out to prepare benzidine-functionalized boron nitride (m-BN). Subsequently, m-BN/poly(p-phenylene benzobisoxazole) nanofiber (PNF) nanocomposite paper with nacre-mimetic layered structures is prepared via sol–gel film transformation approach. The obtained m-BN/PNF nanocomposite paper with 50 wt% m-BN presents excellent thermal conductivity, incredible electrical insulation, outstanding mechanical properties and thermal stability, due to the construction of extensive hydrogen bonds and π–π interactions between m-BN and PNF, and stable nacre-mimetic layered structures. Its λ_∥ and λ_⊥ are 9.68 and 0.84 W m⁻¹ K⁻¹, and the volume resistivity and breakdown strength are as high as 2.3 × 10¹⁵ Ω cm and 324.2 kV mm⁻¹, respectively. Besides, it also presents extremely high tensile strength of 193.6 MPa and thermal decomposition temperature of 640 °C, showing a broad application prospect in high-end thermal management fields such as electronic devices and electrical equipment.

Highlights:
1 m-BN/PNF nanocomposite paper with nacre-mimetic layered structures prepared via sol–gel film transformation approach presents excellent thermal conductivity, incredible electrical insulation, outstanding mechanical property and thermal stability.
2 When the mass fraction of m-BN is 50 wt%, m-BN/PNF nanocomposite paper exhibits excellent thermal conductivity and electrical insulation. The λ∥ and λ⊥ are 9.68 and 0.84 W m⁻¹ K⁻¹, and the volume resistivity and breakdown strength are as high as 2.3 × 1015 Ω cm and 324.2 kV mm⁻¹, respectively.
3 The m-BN/PNF nanocomposite paper with 50 wt% m-BN also presents outstanding mechanical properties (tensile strength of 193.6 MPa) and thermal stability (thermal decomposition temperature of 640 °C).

MXene Enhanced 3D Needled Waste Denim Felt for High-Performance Flexible Supercapacitors

Wed, 29 Nov 2023 00:00:00 +0000

MXene, a transition metal carbide/nitride, has been prominent as an ideal electrochemical active material for supercapacitors. However, the low MXene load limits its practical applications. As environmental concerns and sustainable development become more widely recognized, it is necessary to explore a greener and cleaner technology to recycle textile by-products such as cotton. The present study proposes an effective 3D fabrication method that uses MXene to fabricate waste denim felt into ultralight and flexible supercapacitors through needling and carbonization. The 3D structure provided more sites for loading MXene onto Z-directional fiber bundles, resulting in more efficient ion exchange between the electrolyte and electrodes. Furthermore, the carbonization process removed the specific adverse groups in MXenes, further improving the specific capacitance, energy density, power density and electrical conductivity of supercapacitors. The electrodes achieve a maximum specific capacitance of 1748.5 mF cm⁻² and demonstrate remarkable cycling stability maintaining more than 94% after 15,000 galvanostatic charge/discharge cycles. Besides, the obtained supercapacitors present a maximum specific capacitance of 577.5 mF cm⁻², energy density of 80.2 μWh cm⁻² and power density of 3 mW cm⁻², respectively. The resulting supercapacitors can be used to develop smart wearable power devices such as smartwatches, laying the foundation for a novel strategy of utilizing waste cotton in a high-quality manner.

Highlights:
1 An ultralight and flexible supercapacitor is developed by an effective 3D fabrication method that uses MXene to fabricate waste denim felt through needling and carbonization.
2 The electrodes have a maximum specific capacitance of 1748.5 mF cm⁻² and demonstrate remarkable cycling stability with more than 94% after 15,000 galvanostatic charge/discharge cycles
3 The loaded more MXene onto Z-directional fiber bundles results in enhanced specific capacitance, energy density and power density of supercapacitors.

Gelatin-Based Metamaterial Hydrogel Films with High Conformality for Ultra-Soft Tissue Monitoring

Wed, 29 Nov 2023 00:00:00 +0000

Implantable hydrogel-based bioelectronics (IHB) can precisely monitor human health and diagnose diseases. However, achieving biodegradability, biocompatibility, and high conformality with soft tissues poses significant challenges for IHB. Gelatin is the most suitable candidate for IHB since it is a collagen hydrolysate and a substantial part of the extracellular matrix found naturally in most tissues. This study used 3D printing ultrafine fiber networks with metamaterial design to embed into ultra-low elastic modulus hydrogel to create a novel gelatin-based conductive film (GCF) with mechanical programmability. The regulation of GCF nearly covers soft tissue mechanics, an elastic modulus from 20 to 420 kPa, and a Poisson's ratio from − 0.25 to 0.52. The negative Poisson's ratio promotes conformality with soft tissues to improve the efficiency of biological interfaces. The GCF can monitor heartbeat signals and respiratory rate by determining cardiac deformation due to its high conformability. Notably, the gelatin characteristics of the biodegradable GCF enable the sensor to monitor and support tissue restoration. The GCF metamaterial design offers a unique idea for bioelectronics to develop implantable sensors that integrate monitoring and tissue repair and a customized method for endowing implanted sensors to be highly conformal with soft tissues.

Highlights:
1 Novel customized metamaterial gelatin-based conductive film (GCF) was developed to ensure good biocompatibility and biodegradability for implantable bioelectronics integrating monitoring with tissue repair. The metamaterial property demonstrated high conformal with soft tissues to promote the signal-to-noise ratio.
2 The GCF revealed elastic modulus regulated from 20 to 420 kPa and Poisson's ratio from − 0.25 to 0.52. It was fabricated by embedding different 3D printing ultrafine fiber networks with metamaterial design into ultra-low modulus Gelatin methacryloyl hydrogel.

Layered Structural PBAT Composite Foams for Efficient Electromagnetic Interference Shielding

Jianming Yang, Hu Wang, Yali Zhang, Hexin Zhang, Junwei Gu — Thu, 23 Nov 2023 00:00:00 +0000

The utilization of eco-friendly, lightweight, high-efficiency and high-absorbing electromagnetic interference (EMI) shielding composites is imperative in light of the worldwide promotion of sustainable manufacturing. In this work, magnetic poly (butyleneadipate-co-terephthalate) (PBAT) microspheres were firstly synthesized via phase separation method, then PBAT composite foams with layered structure was constructed through the supercritical carbon dioxide foaming and scraping techniques. The merits of integrating ferroferric oxide-loaded multi-walled carbon nanotubes (Fe₃O₄@MWCNTs) nanoparticles, a microcellular framework, and a highly conductive silver layer have been judiciously orchestrated within this distinctive layered configuration. Microwaves are consumed throughout the process of “absorption-reflection-reabsorption” as much as possible, which greatly declines the secondary radiation pollution. The biodegradable PBAT composite foams achieved an EMI shielding effectiveness of up to 68 dB and an absorptivity of 77%, and authenticated favorable stabilization after the tape adhesion experiment.

Highlights:
1 A layered segregated shielding network was organized in porous PBAT/Fe₃O₄@MWCNTs/Ag composite by scCO₂ foaming and scraping techniques.
2 The composite foam achieved an electromagnetic interference (EMI) shielding effectiveness (SE) of up to 68.0 dB and a reflectivity of as low as 23% due to the “absorption-reflection-re-absorption” shielding mechanism.
3 The solid and foamed PBAT/Fe₃O₄@MWCNTs/Ag composites displayed superior retention (> 92%) of EMI SE even after peeling experiment of 500 times under 100 g weight pressure.

Step-by-Step Modulation of Crystalline Features and Exciton Kinetics for 19.2% Efficiency Ortho-Xylene Processed Organic Solar Cells

Thu, 23 Nov 2023 00:00:00 +0000

With plenty of popular and effective ternary organic solar cells (OSCs) construction strategies proposed and applied, its power conversion efficiencies (PCEs) have come to a new level of over 19% in single-junction devices. However, previous studies are heavily based in chloroform (CF) leaving behind substantial knowledge deficiencies in understanding the influence of solvent choice when introducing a third component. Herein, we present a case where a newly designed asymmetric small molecular acceptor using fluoro-methoxylated end-group modification strategy, named BTP-BO-3FO with enlarged bandgap, brings different morphological evolution and performance improvement effect on host system PM6:BTP-eC9, processed by CF and ortho-xylene (o-XY). With detailed analyses supported by a series of experiments, the best PCE of 19.24% for green solvent-processed OSCs is found to be a fruit of finely tuned crystalline ordering and general aggregation motif, which furthermore nourishes a favorable charge generation and recombination behavior. Likewise, over 19% PCE can be achieved by replacing spin-coating with blade coating for active layer deposition. This work focuses on understanding the commonly met yet frequently ignored issues when building ternary blends to demonstrate cutting-edge device performance, hence, will be instructive to other ternary OSC works in the future.

Highlights:
1 A novel fluoro-methoxylated end group for Y-series acceptors is produced, and asymmetric substitution strategy is applied as a step-by-step optimization.
2 19.24% power conversion efficiency is achieved for industrially compatible solvent ortho-xylene processed organic solar cells.
2 Underlying morphological and photo-physical variation is revealed for device performance difference brought by solvent selection, which could set up a template for future research on similar topics.

Atomically Dispersed Ruthenium Catalysts with Open Hollow Structure for Lithium–Oxygen Batteries

Tue, 21 Nov 2023 00:00:00 +0000

Lithium–oxygen battery with ultra-high theoretical energy density is considered a highly competitive next-generation energy storage device, but its practical application is severely hindered by issues such as difficult decomposition of discharge products at present. Here, we have developed N-doped carbon anchored atomically dispersed Ru sites cathode catalyst with open hollow structure (h-RuNC) for Lithium–oxygen battery. On one hand, the abundance of atomically dispersed Ru sites can effectively catalyze the formation and decomposition of discharge products, thereby greatly enhancing the redox kinetics. On the other hand, the open hollow structure not only enhances the mass activity of atomically dispersed Ru sites but also improves the diffusion efficiency of catalytic molecules. Therefore, the excellent activity from atomically dispersed Ru sites and the enhanced diffusion from open hollow structure respectively improve the redox kinetics and cycling stability, ultimately achieving a high-performance lithium–oxygen battery.

Highlights:
1 The open hollow structure enhances the accessibility of atomically dispersed Ru sites and improves the diffusion efficiency of catalytic molecules
2 The abundant atomically dispersed Ru sites on the surface of catalyst provide a large number of oxygen adsorption and Li₂O₂ nucleation sites
3 The lithium–oxygen battery assembled with h-RuNC could catalyze the production of Li₂O₂ with better dispersion and improve the cycling stability.

A Selective-Response Hypersensitive Bio-Inspired Strain Sensor Enabled by Hysteresis Effect and Parallel Through-Slits Structures

Mon, 20 Nov 2023 00:00:00 +0000

Flexible strain sensors are promising in sensing minuscule mechanical signals, and thereby widely used in various advanced fields. However, the effective integration of hypersensitivity and highly selective response into one flexible strain sensor remains a huge challenge. Herein, inspired by the hysteresis strategy of the scorpion slit receptor, a bio-inspired flexible strain sensor (BFSS) with parallel through-slit arrays is designed and fabricated. Specifically, BFSS consists of conductive monolayer graphene and viscoelastic styrene–isoprene–styrene block copolymer. Under the synergistic effect of the bio-inspired slit structures and flexible viscoelastic materials, BFSS can achieve both hypersensitivity and highly selective frequency response. Remarkably, the BFSS exhibits a high gage factor of 657.36, and a precise identification of vibration frequencies at a resolution of 0.2 Hz through undergoing different morphological changes to high-frequency vibration and low-frequency vibration. Moreover, the BFSS possesses a wide frequency detection range (103 Hz) and stable durability (1000 cycles). It can sense and recognize vibration signals with different characteristics, including the frequency, amplitude, and waveform. This work, which turns the hysteresis effect into a "treasure," can provide new design ideas for sensors for potential applications including human–computer interaction and health monitoring of mechanical equipment.

Highlights:
1 A bio-inspired flexible strain sensor with hypersensitivity and highly selective frequency response is prepared by styrene–isoprene–styrene combined with monolayer graphene.
2 Benefiting from the structural design inspired by nature and hysteresis of viscoelastic materials, bio-inspired structures, and original materials' properties complement each other.
3 The frequency recognition resolution of bio-inspired flexible strain sensor reaches 0.2 Hz, making it ideal for human–computer interaction and mechanical equipment health inspection.

Coaxial Wet Spinning of Boron Nitride Nanosheet-Based Composite Fibers with Enhanced Thermal Conductivity and Mechanical Strength

Wenjiang Lu, Qixuan Deng, Minsu Liu, Baofu Ding, Zhiyuan Xiong, Ling Qiu — Mon, 20 Nov 2023 00:00:00 +0000

Hexagonal boron nitride nanosheets (BNNSs) exhibit remarkable thermal and dielectric properties. However, their self-assembly and alignment in macroscopic forms remain challenging due to the chemical inertness of boron nitride, thereby limiting their performance in applications such as thermal management. In this study, we present a coaxial wet spinning approach for the fabrication of BNNSs/polymer composite fibers with high nanosheet orientation. The composite fibers were prepared using a superacid-based solvent system and showed a layered structure comprising an aramid core and an aramid/BNNSs sheath. Notably, the coaxial fibers exhibited significantly higher BNNSs alignment compared to uniaxial aramid/BNNSs fibers, primarily due to the additional compressive forces exerted at the core-sheath interface during the hot drawing process. With a BNNSs loading of 60 wt%, the resulting coaxial fibers showed exceptional properties, including an ultrahigh Herman orientation parameter of 0.81, thermal conductivity of 17.2 W m⁻¹ K⁻¹, and tensile strength of 192.5 MPa. These results surpassed those of uniaxial fibers and previously reported BNNSs composite fibers, making them highly suitable for applications such as wearable thermal management textiles. Our findings present a promising strategy for fabricating high-performance composite fibers based on BNNSs.

Highlights:
1 A core-sheath structured coaxial composite fiber with highly aligned and densely stacked boron nitride nanosheets arrangements in the sheath was successfully fabricated.
2 The coaxial fibers have an ultrahigh axial Herman orientation parameter of 0.81, thermal conductivity of 17.2 W m⁻¹ K⁻¹, and tensile strength of 192.5 MPa.
3 The coaxial fibers exhibit intensively potential applications in the wearable thermal management textile.

Coupling of Adhesion and Anti-Freezing Properties in Hydrogel Electrolytes for Low-Temperature Aqueous-Based Hybrid Capacitors

Mon, 20 Nov 2023 00:00:00 +0000

Solid-state zinc-ion capacitors are emerging as promising candidates for large-scale energy storage owing to improved safety, mechanical and thermal stability and easy-to-direct stacking. Hydrogel electrolytes are appealing solid-state electrolytes because of eco-friendliness, high conductivity and intrinsic flexibility. However, the electrolyte/electrode interfacial contact and anti-freezing properties of current hydrogel electrolytes are still challenging for practical applications of zinc-ion capacitors. Here, we report a class of hydrogel electrolytes that couple high interfacial adhesion and anti-freezing performance. The synergy of tough hydrogel matrix and chemical anchorage enables a well-adhered interface between hydrogel electrolyte and electrode. Meanwhile, the cooperative solvation of ZnCl₂ and LiCl hybrid salts renders the hydrogel electrolyte high ionic conductivity and mechanical elasticity simultaneously at low temperatures. More significantly, the Zn||carbon nanotubes hybrid capacitor based on this hydrogel electrolyte exhibits low-temperature capacitive performance, delivering high-energy density of 39 Wh kg⁻¹ at −60 °C with capacity retention of 98.7% over 10,000 cycles. With the benefits of the well-adhered electrolyte/electrode interface and the anti-freezing hydrogel electrolyte, the Zn/Li hybrid capacitor is able to accommodate dynamic deformations and function well under 1000 tension cycles even at −60 °C. This work provides a powerful strategy for enabling stable operation of low-temperature zinc-ion capacitors.

Highlights:
1 A class of hydrogel electrolytes that couple high adhesion and anti-freezing properties is developed.
2 Zn/Li hybrid capacitors based on the hydrogel electrolyte can tolerate low temperatures and accommodate dynamic deformations across a temperature range of 25 to − 60 °C.
3 This work highlights an advancement for promoting next-generation energy storage system with low-temperature capability and mechanical durability.

A Stable Open-Shell Conjugated Diradical Polymer with Ultra-High Photothermal Conversion Efficiency for NIR-II Photo-Immunotherapy of Metastatic Tumor

Mon, 20 Nov 2023 00:00:00 +0000

Massive efforts have been concentrated on the advance of eminent near-infrared (NIR) photothermal materials (PTMs) in the NIR-II window (1000–1700 nm), especially organic PTMs because of their intrinsic biological safety compared with inorganic PTMs. However, so far, only a few NIR-II-responsive organic PTMs was explored, and their photothermal conversion efficiencies (PCEs) still remain relatively low. Herein, donor–acceptor conjugated diradical polymers with open-shell characteristics are explored for synergistically photothermal immunotherapy of metastatic tumors in the NIR-II window. By employing side-chain regulation, the conjugated diradical polymer TTB-2 with obvious NIR-II absorption was developed, and its nanoparticles realize a record-breaking PCE of 87.7% upon NIR-II light illustration. In vitro and in vivo experiments demonstrate that TTB-2 nanoparticles show good tumor photoablation with navigation of photoacoustic imaging in the NIR-II window, without any side-effect. Moreover, by combining with PD-1 antibody, the pulmonary metastasis of breast cancer is high-effectively prevented by the efficient photo-immunity effect. Thus, this study explores superior PTMs for cancer metastasis theranostics in the NIR-II window, offering a new horizon in developing radical-characteristic NIR-II photothermal materials.

Highlights:
1 By employing side-chain regulation, the photothermal therapy response of conjugated diradical polymer can red-shift from near-infrared (NIR)-I to the NIR-II region. This strategy offers new radical materials in developing NIR-II photothermal materials.
2 The conjugated diradical polymer TTB-2 receives a record-high photothermal conversion efficiency of 87.7%, far beyond the recently reported NIR-II photothermal agents. Such conjugated diradical polymer must enrich the NIR-II photothermal agents’ library and provide important insight for more diradical polymer construction.
3 The conjugated diradical polymer nanoparticles TTB-2 NPs achieve good tumor photoablation with navigation of photoacoustic imaging in the NIR-II window, without any side effect. Furthermore, the efficient photo-immunity effect prevents the pulmonary metastasis of breast cancer.

Efficient Electromagnetic Wave Absorption and Thermal Infrared Stealth in PVTMS@MWCNT Nano-Aerogel via Abundant Nano-Sized Cavities and Attenuation Interfaces

Fri, 17 Nov 2023 00:00:00 +0000

Pre-polymerized vinyl trimethoxy silane (PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization, sol–gel transition and supercritical CO₂ drying. The fabricated organic–inorganic hybrid PVTMS@MWCNT aerogel structure shows nano-pore size (30–40 nm), high specific surface area (559 m² g⁻¹), high void fraction (91.7%) and enhanced mechanical property: (1) the nano-pore size is beneficial for efficiently blocking thermal conduction and thermal convection via Knudsen effect (beneficial for infrared (IR) stealth); (2) the heterogeneous interface was beneficial for IR reflection (beneficial for IR stealth) and MWCNT polarization loss (beneficial for electromagnetic wave (EMW) attenuation); (3) the high void fraction was beneficial for enhancing thermal insulation (beneficial for IR stealth) and EMW impedance match (beneficial for EMW attenuation). Guided by the above theoretical design strategy, PVTMS@MWCNT nano-aerogel shows superior EMW absorption property (cover all Ku-band) and thermal IR stealth property (ΔT reached 60.7 °C). Followed by a facial combination of the above nano-aerogel with graphene film of high electrical conductivity, an extremely high electromagnetic interference shielding material (66.5 dB, 2.06 mm thickness) with superior absorption performance of an average absorption-to-reflection (A/R) coefficient ratio of 25.4 and a low reflection bandwidth of 4.1 GHz (A/R ratio more than 10) was experimentally obtained in this work.

Highlights:
1 PVTMS@MWCNT nano-aerogel with nano-pore size and abundant heterogeneous interface was fabricated via radical polymerization, sol–gel transition and CO₂ drying.
2 The nano-aerogel shows superior electromagnetic wave absorption property (RLmin = −36.1 dB and cover all Ku-band) and thermal infrared stealth property (ΔT reached 60.7 °C).
3 Layered nano-aerogel/graphene film with high EMI shielding and absorption properties was obtained;

Twisted Integration of Complex Oxide Magnetoelectric Heterostructures via Water-Etching and Transfer Process

Fri, 17 Nov 2023 00:00:00 +0000

Manipulating strain mode and degree that can be applied to epitaxial complex oxide thin films have been a cornerstone of strain engineering. In recent years, lift-off and transfer technology of the epitaxial oxide thin films have been developed that enabled the integration of heterostructures without the limitation of material types and crystal orientations. Moreover, twisted integration would provide a more interesting strategy in artificial magnetoelectric heterostructures. A specific twist angle between the ferroelectric and ferromagnetic oxide layers corresponds to the distinct strain regulation modes in the magnetoelectric coupling process, which could provide some insight in to the physical phenomena. In this work, the La_0.67Sr_0.33MnO₃ (001)/0.7Pb(Mg_1/3Nb_2/3)O₃–0.3PbTiO₃ (011) (LSMO/PMN-PT) heterostructures with 45º and 0º twist angles were assembled via water-etching and transfer process. The transferred LSMO films exhibit a fourfold magnetic anisotropy with easy axis along LSMO < 110 >. A coexistence of uniaxial and fourfold magnetic anisotropy with LSMO [110] easy axis is observed for the 45° Sample by applying a 7.2 kV cm⁻¹ electrical field, significantly different from a uniaxial anisotropy with LSMO [100] easy axis for the 0° Sample. The fitting of the ferromagnetic resonance field reveals that the strain coupling generated by the 45° twist angle causes different lattice distortion of LSMO, thereby enhancing both the fourfold and uniaxial anisotropy. This work confirms the twisting degrees of freedom for magnetoelectric coupling and opens opportunities for fabricating artificial magnetoelectric heterostructures.

Highlights:
1 The (001)-oriented ferromagnetic La_0.67Sr_0.33MnO₃ films are stuck onto the (011)-oriented ferroelectric single-crystal 0.7Pb(Mg_1/3Nb_2/3)O₃–0.3PbTiO₃ substrate with 0° and 45° twist angle.
2 By applying a 7.2 kV cm⁻¹ electric field, the coexistence of uniaxial and fourfold in-plane magnetic anisotropy is observed in 45° Sample, while a typical uniaxial anisotropy is found in 0° Sample.

In Situ Deposition of Drug and Gene Nanoparticles on a Patterned Supramolecular Hydrogel to Construct a Directionally Osteochondral Plug

Fri, 17 Nov 2023 00:00:00 +0000

The integrated repair of bone and cartilage boasts advantages for osteochondral restoration such as a long-term repair effect and less deterioration compared to repairing cartilage alone. Constructing multifactorial, spatially oriented scaffolds to stimulate osteochondral regeneration, has immense significance. Herein, targeted drugs, namely kartogenin@polydopamine (KGN@PDA) nanoparticles for cartilage repair and miRNA@calcium phosphate (miRNA@CaP) NPs for bone regeneration, were in situ deposited on a patterned supramolecular-assembled 2-ureido-4 [lH]-pyrimidinone (UPy) modified gelation hydrogel film, facilitated by the dynamic and responsive coordination and complexation of metal ions and their ligands. This hydrogel film can be rolled into a cylindrical plug, mimicking the Haversian canal structure of natural bone. The resultant hydrogel demonstrates stable mechanical properties, a self-healing ability, a high capability for reactive oxygen species capture, and controlled release of KGN and miR-26a. In vitro, KGN@PDA and miRNA@CaP promote chondrogenic and osteogenic differentiation of mesenchymal stem cells via the JNK/RUNX1 and GSK-3β/β-catenin pathways, respectively. In vivo, the osteochondral plug exhibits optimal subchondral bone and cartilage regeneration, evidenced by a significant increase in glycosaminoglycan and collagen accumulation in specific zones, along with the successful integration of neocartilage with subchondral bone. This biomaterial delivery approach represents a significant toward improved osteochondral repair.

Highlights:
1 A multifactorial and oriented scaffolds was constructed to stimulate osteochondral regeneration.
2 This is the first demonstration that both drug and gene nanoparticles were spatially deposited on a patterned film through metal-ligand interactions.
3 For the first time, film-rolling approach was employed to construct osteochondral plug to mimick the Haversian canal structure of natural bone.

Highly Thermoconductive, Strong Graphene-Based Composite Films by Eliminating Nanosheets Wrinkles

Guang Xiao, Hao Li, Zhizhou Yu, Haoting Niu, Yagang Yao — Fri, 17 Nov 2023 00:00:00 +0000

Graphene-based thermally conductive composites have been proposed as effective thermal management materials for cooling high-power electronic devices. However, when flexible graphene nanosheets are assembled into macroscopic thermally conductive composites, capillary forces induce shrinkage of graphene nanosheets to form wrinkles during solution-based spontaneous drying, which greatly reduces the thermal conductivity of the composites. Herein, graphene nanosheets/aramid nanofiber (GNS/ANF) composite films with high thermal conductivity were prepared by in-plane stretching of GNS/ANF composite hydrogel networks with hydrogen bonds and π–π interactions. The in-plane mechanical stretching eliminates graphene nanosheets wrinkles by suppressing inward shrinkage due to capillary forces during drying and achieves a high in-plane orientation of graphene nanosheets, thereby creating a fast in-plane heat transfer channel. The composite films (GNS/ANF-60 wt%) with eliminated graphene nanosheets wrinkles showed a significant increase in thermal conductivity (146 W m⁻¹ K⁻¹) and tensile strength (207 MPa). The combination of these excellent properties enables the GNS/ANF composite films to be effectively used for cooling flexible LED chips and smartphones, showing promising applications in the thermal management of high-power electronic devices.

Highlights:
1 Highly thermally conductive composite films with elimination of graphene nanosheet wrinkles prepared by a constrained drying strategy of in-plane stretching.
2 Reveals the mechanism of graphene nanosheet wrinkle elimination to improve the thermal conductivity of composite films and demonstrates its use as a heat sink film for cooling flexible LED chips and smartphones.

Nitrogen-Doped Magnetic-Dielectric-Carbon Aerogel for High-Efficiency Electromagnetic Wave Absorption

Fri, 17 Nov 2023 00:00:00 +0000

Carbon-based aerogels derived from biomass chitosan are encountering a flourishing moment in electromagnetic protection on account of lightweight, controllable fabrication and versatility. Nevertheless, developing a facile construction method of component design with carbon-based aerogels for high-efficiency electromagnetic wave absorption (EWA) materials with a broad effective absorption bandwidth (EAB) and strong absorption yet hits some snags. Herein, the nitrogen-doped magnetic-dielectric-carbon aerogel was obtained via ice template method followed by carbonization treatment, homogeneous and abundant nickel (Ni) and manganese oxide (MnO) particles in situ grew on the carbon aerogels. Thanks to the optimization of impedance matching of dielectric/magnetic components to carbon aerogels, the nitrogen-doped magnetic-dielectric-carbon aerogel (Ni/MnO-CA) suggests a praiseworthy EWA performance, with an ultra-wide EAB of 7.36 GHz and a minimum reflection loss (RL_min) of − 64.09 dB, while achieving a specific reflection loss of − 253.32 dB mm⁻¹. Furthermore, the aerogel reveals excellent radar stealth, infrared stealth, and thermal management capabilities. Hence, the high-performance, easy fabricated and multifunctional nickel/manganese oxide/carbon aerogels have broad application aspects for electromagnetic protection, electronic devices and aerospace.

Highlights:
1 An ingenious design achieved magnetic-dielectric-carbon coupling.
2 Nickel and manganese oxide particles were in situ reduced and grew on the carbon aerogels.
3 The aerogels demonstrated radar stealth, infrared stealth and thermal management capability.

Structural Isomers: Small Change with Big Difference in Anion Storage

Mon, 13 Nov 2023 00:00:00 +0000

Organic electrode materials are promising for batteries. However, the reported organic electrodes are often facing the challenges of low specific capacity, low voltage, poor rate capability and vague charge storage mechanisms, etc. Isomers are good platform to investigate the charge storage mechanisms and enhance the performance of batteries, which, however, have not been focused in batteries. Herein, two isomers are reported for batteries. As a result, the isomer tetrathiafulvalene (TTF) could store two monovalent anions reversibly, deriving an average discharge voltage of 1.05 V and a specific capacity of 220 mAh g⁻¹ at a current density of 2 C. On the other hand, the other isomer tetrathianaphthalene could only reversibly store one monovalent anion and upon further oxidation, it would undergo an irreversible solid-state molecular rearrangement to TTF. The molecular rearrangement was confirmed by electrochemical performances, X-ray diffraction patterns, nuclear magnetic resonance spectra, and ¹H detected heteronuclear multiple bond correlation spectra. These results suggested the small structural change could lead to a big difference in anion storage, and we hope this work will stimulate more attention to the structural design for boosting the performance of organic batteries.

Highlights:
1 The effect of small changes in isomers on electrochemical performance have not been focused in batteries and two isomers are reported for Zn-ion batteries here.
2 The isomer tetrathiafulvalene (TTF) could store two monovalent anions reversibly, showing remarkable performance that outperformed most of the reported organic electrode materials for zinc-ion batteries.
3 The isomer tetrathianaphthalene (TTN) could only reversibly store one monovalent anion and upon further oxidation, it would undergo an irreversible solid-state molecular rearrangement to TTF.

Intelligent Recognition Using Ultralight Multifunctional Nano-Layered Carbon Aerogel Sensors with Human-Like Tactile Perception

Thu, 09 Nov 2023 00:00:00 +0000

Humans can perceive our complex world through multi-sensory fusion. Under limited visual conditions, people can sense a variety of tactile signals to identify objects accurately and rapidly. However, replicating this unique capability in robots remains a significant challenge. Here, we present a new form of ultralight multifunctional tactile nano-layered carbon aerogel sensor that provides pressure, temperature, material recognition and 3D location capabilities, which is combined with multimodal supervised learning algorithms for object recognition. The sensor exhibits human-like pressure (0.04–100 kPa) and temperature (21.5–66.2 °C) detection, millisecond response times (11 ms), a pressure sensitivity of 92.22 kPa⁻¹ and triboelectric durability of over 6000 cycles. The devised algorithm has universality and can accommodate a range of application scenarios. The tactile system can identify common foods in a kitchen scene with 94.63% accuracy and explore the topographic and geomorphic features of a Mars scene with 100% accuracy. This sensing approach empowers robots with versatile tactile perception to advance future society toward heightened sensing, recognition and intelligence.

Highlights:
1 individual sensor can provide multiple tactile sensations: pressure, temperature, materials recognition, and 3D location. ThereforThe tactile performance of ultralight multifunctional sensors can reach the level of human tactile perception.
2 An e, it is no longer necessary to integrate multiple sensing modules with different functions, which greatly simplifies system complexity and reduces energy loss.
3 The tactile system with multimodal learning algorithms has universality and can accommodate object recognition tasks in various application scenarios (e.g., Mars and Kitchen).

High-Entropy Layered Oxide Cathode Enabling High-Rate for Solid-State Sodium-Ion Batteries

Mon, 13 Nov 2023 00:00:00 +0000

Na-ion O3-type layered oxides are prospective cathodes for Na-ion batteries due to high energy density and low-cost. Nevertheless, such cathodes usually suffer from phase transitions, sluggish kinetics and air instability, making it difficult to achieve high performance solid-state sodium-ion batteries. Herein, the high-entropy design and Li doping strategy alleviate lattice stress and enhance ionic conductivity, achieving high-rate performance, air stability and electrochemically thermal stability for Na_0.95Li_0.06Ni_0.25Cu_0.05Fe_0.15Mn_0.49O₂. This cathode delivers a high reversible capacity (141 mAh g⁻¹ at 0.2C), excellent rate capability (111 mAh g⁻¹ at 8C, 85 mAh g⁻¹ even at 20C), and long-term stability (over 85% capacity retention after 1000 cycles), which is attributed to a rapid and reversible O3–P3 phase transition in regions of low voltage and suppresses phase transition. Moreover, the compound remains unchanged over seven days and keeps thermal stability until 279 ℃. Remarkably, the polymer solid-state sodium battery assembled by this cathode provides a capacity of 92 mAh g⁻¹ at 5C and keeps retention of 96% after 400 cycles. This strategy inspires more rational designs and could be applied to a series of O3 cathodes to improve the performance of solid-state Na-ion batteries.

Highlights:
1 High-entropy oxides O3-Na_0.95Li_0.06Ni_0.25Cu_0.05Fe_0.15Mn_0.49O₂ cathode constructed by compatible radius and different Fermi level ions was designed for solid-state Na-ion batteries.
2 Na_0.95Li_0.06Ni_0.25Cu_0.05Fe_0.15Mn_0.49O₂ cathode exhibits high-rate performance, air stability and electrochemically thermal stability.
3 A series of characterizations were performed to explore energy storage mechanism of Na_0.95Li_0.06Ni_0.25Cu_0.05Fe_0.15Mn_0.49O₂.

Oxygen-Coordinated Single Mn Sites for Efficient Electrocatalytic Nitrate Reduction to Ammonia

Mon, 13 Nov 2023 00:00:00 +0000

Electrocatalytic nitrate reduction reaction has attracted increasing attention due to its goal of low carbon emission and environmental protection. Here, we report an efficient NitRR catalyst composed of single Mn sites with atomically dispersed oxygen (O) coordination on bacterial cellulose-converted graphitic carbon (Mn–O–C). Evidence of the atomically dispersed Mn–(O–C₂)₄ moieties embedding in the exposed basal plane of carbon surface is confirmed by X-ray absorption spectroscopy. As a result, the as-synthesized Mn–O–C catalyst exhibits superior NitRR activity with an NH₃ yield rate (R_NH3) of 1476.9 ± 62.6 μg h⁻¹ cm⁻² at − 0.7 V (vs. reversible hydrogen electrode, RHE) and a faradaic efficiency (FE) of 89.0 ± 3.8% at − 0.5 V (vs. RHE) under ambient conditions. Further, when evaluated with a practical flow cell, Mn–O–C shows a high R_NH3 of 3706.7 ± 552.0 μg h⁻¹ cm⁻² at a current density of 100 mA cm⁻², 2.5 times of that in the H cell. The in situ FT-IR and Raman spectroscopic studies combined with theoretical calculations indicate that the Mn–(O–C₂)₄ sites not only effectively inhibit the competitive hydrogen evolution reaction, but also greatly promote the adsorption and activation of nitrate (NO₃⁻), thus boosting both the FE and selectivity of NH₃ over Mn–(O–C₂)₄ sites.

Highlights:
1 Oxygen-coordinated single-atom Mn catalyst was fabricated via introducing oxygen functional groups rich bacterial cellulose as the adsorption regulator through a combined impregnation–pyrolysis–etching synthetic route.
2 Mn–O–C as the electrocatalyst exhibits superior electrocatalytic activity toward ammonia synthesis with a maximum NH₃ yield rate of 1476.9 ± 62.6 μg h⁻¹ cm⁻² at − 0.7 V (vs. RHE) and a faradaic efficiency of 89.0 ± 3.8% at − 0.5 V (vs. RHE) under ambient conditions.
3 Electrocatalytic mechanism of Mn–(O–C₂)₄ site for nitrate reduction reaction is unveiled by a combination of in situ spectroscopy characterization and computational study.

Ionization Engineering of Hydrogels Enables Highly Efficient Salt-Impeded Solar Evaporation and Night-Time Electricity Harvesting

Nan He, Haonan Wang, Haotian Zhang, Bo Jiang, Dawei Tang, Lin Li — Mon, 13 Nov 2023 00:00:00 +0000

Interfacial solar evaporation holds immense potential for brine desalination with low carbon footprints and high energy utilization. Hydrogels, as a tunable material platform from the molecular level to the macroscopic scale, have been considered the most promising candidate for solar evaporation. However, the simultaneous achievement of high evaporation efficiency and satisfactory tolerance to salt ions in brine remains a challenging scientific bottleneck, restricting the widespread application. Herein, we report ionization engineering, which endows polymer chains of hydrogels with electronegativity for impeding salt ions and activating water molecules, fundamentally overcoming the hydrogel salt-impeded challenge and dramatically expediting water evaporating in brine. The sodium dodecyl benzene sulfonate-modified carbon black is chosen as the solar absorbers. The hydrogel reaches a ground-breaking evaporation rate of 2.9 kg m⁻² h⁻¹ in 20 wt% brine with 95.6% efficiency under one sun irradiation, surpassing most of the reported literature. More notably, such a hydrogel-based evaporator enables extracting clean water from oversaturated salt solutions and maintains durability under different high-strength deformation or a 15-day continuous operation. Meantime, on the basis of the cation selectivity induced by the electronegativity, we first propose an all-day system that evaporates during the day and generates salinity-gradient electricity using waste-evaporated brine at night, anticipating pioneer a new opportunity for all-day resource-generating systems in fields of freshwater and electricity.

Highlights:
1 An ionization-engineered hydrogel with electronegativity polymer chains to impede salt ions was designed.
2 The hydrogel evaporator exhibited salt impedance in 20 wt% brine for 15 days with a high evaporation efficiency of 95.6%.
3 An all-day high-salinity brine treatment with zero liquid discharge was proposed.

Multiphase Interfacial Regulation Based on Hierarchical Porous Molybdenum Selenide to Build Anticorrosive and Multiband Tailorable Absorbers

Tianbao Zhao, Zirui Jia, Jinkun Liu, Yan Zhang, Guanglei Wu, Pengfei Yin — Mon, 13 Nov 2023 00:00:00 +0000

Electromagnetic wave (EMW) absorbing materials have an irreplaceable position in the field of military stealth as well as in the field of electromagnetic pollution control. And in order to cope with the complex electromagnetic environment, the design of multifunctional and multiband high efficiency EMW absorbers remains a tremendous challenge. In this work, we designed a three-dimensional porous structure via the salt melt synthesis strategy to optimize the impedance matching of the absorber. Also, through interfacial engineering, a molybdenum carbide transition layer was introduced between the molybdenum selenide nanoparticles and the three-dimensional porous carbon matrix to improve the absorption behavior of the absorber. The analysis indicates that the number and components of the heterogeneous interfaces have a significant impact on the EMW absorption performance of the absorber due to mechanisms such as interfacial polarization and conduction loss introduced by interfacial engineering. Wherein, the prepared MoSe₂/MoC/PNC composites showed excellent EMW absorption performance in C, X, and K_u bands, especially exhibiting a reflection loss of − 59.09 dB and an effective absorption bandwidth of 6.96 GHz at 1.9 mm. The coordination between structure and components endows the absorber with strong absorption, broad bandwidth, thin thickness, and multi-frequency absorption characteristics. Remarkably, it can effectively reinforce the marine anticorrosion property of the epoxy resin coating on Q235 steel substrate. This study contributes to a deeper understanding of the relationship between interfacial engineering and the performance of EMW absorbers, and provides a reference for the design of multifunctional, multiband EMW absorption materials.

Highlights:
1 The hierarchical porous structure is regulated by various species of PVP to achieve impedance matching.
2 Interfacial engineering boosts conductivity and constructs a multiband (C, X, Ku) tunable electromagnetic wave absorber.
3 Hierarchical porous molybdenum selenide/epoxy coating exhibits marine anticorrosion capability.

Understanding Bridging Sites and Accelerating Quantum Efficiency for Photocatalytic CO2 Reduction

Mon, 13 Nov 2023 00:00:00 +0000

We report a novel double-shelled nanoboxes photocatalyst architecture with tailored interfaces that accelerate quantum efficiency for photocatalytic CO₂ reduction reaction (CO₂RR) via Mo–S bridging bonds sites in S_v–In₂S₃@2H–MoTe₂. The X-ray absorption near-edge structure shows that the formation of S_v–In₂S₃@2H–MoTe₂ adjusts the coordination environment via interface engineering and forms Mo–S polarized sites at the interface. The interfacial dynamics and catalytic behavior are clearly revealed by ultrafast femtosecond transient absorption, time-resolved, and in situ diffuse reflectance–Infrared Fourier transform spectroscopy. A tunable electronic structure through steric interaction of Mo–S bridging bonds induces a 1.7-fold enhancement in S_v–In₂S₃@2H–MoTe₂(5) photogenerated carrier concentration relative to pristine S_v–In₂S₃. Benefiting from lower carrier transport activation energy, an internal quantum efficiency of 94.01% at 380 nm was used for photocatalytic CO₂RR. This study proposes a new strategy to design photocatalyst through bridging sites to adjust the selectivity of photocatalytic CO₂RR.

Highlights:
1 The S-vacancies result in the change of d-band electronic state of Mo.
2 An internal quantum efficiency of 94.01% at 380 nm for photocatalytic CO₂ reduction reaction (CO₂RR).
3 The Mo–S bridging bonds optimize adsorption energies and accelerate CO₂RR kinetics.

Atomic Dispersed Hetero-Pairs for Enhanced Electrocatalytic CO2 Reduction

Mon, 13 Nov 2023 00:00:00 +0000

Electrochemical carbon dioxide reduction reaction (CO₂RR) involves a variety of intermediates with highly correlated reaction and ad-desorption energies, hindering optimization of the catalytic activity. For example, increasing the binding of the *COOH to the active site will generally increase the *CO desorption energy. Breaking this relationship may be expected to dramatically improve the intrinsic activity of CO₂RR, but remains an unsolved challenge. Herein, we addressed this conundrum by constructing a unique atomic dispersed hetero-pair consisting of Mo-Fe di-atoms anchored on N-doped carbon carrier. This system shows an unprecedented CO₂RR intrinsic activity with TOF of 3336 h⁻¹, high selectivity toward CO production, Faradaic efficiency of 95.96% at − 0.60 V and excellent stability. Theoretical calculations show that the Mo-Fe diatomic sites increased the *COOH intermediate adsorption energy by bridging adsorption of *COOH intermediates. At the same time, d-d orbital coupling in the Mo-Fe di-atom results in electron delocalization and facilitates desorption of *CO intermediates. Thus, the undesirable correlation between these steps is broken. This work provides a promising approach, specifically the use of di-atoms, for breaking unfavorable relationships based on understanding of the catalytic mechanisms at the atomic scale.

Highlights:
1 A unique atomic dispersed hetero-pair was successfully synthesized, consisting of Mo-Fe di-atoms anchored on N-doped carbon carrier.
2 This strategy breaks the linear scaling relationships of electrocatalytic CO₂ reduction by simultaneously regulating the *COOH adsorption energy and *CO desorption energy.
3 The as-prepared MoFe–N–C exhibits excellent performance for CO₂RR to CO with a high turnover frequency (TOF) of 3336.21 h⁻¹, CO Faradaic efficiency (FECO) of 95.96% at − 0.60 V (versus RHE) and outstanding stability.

Core–Shell Microfiber Encapsulation Enables Glycerol-Free Cryopreservation of RBCs with High Hematocrit

Xianhui Qin, Zhongrong Chen, Lingxiao Shen, Huilan Liu, Xilin Ouyang, Gang Zhao — Mon, 13 Nov 2023 00:00:00 +0000

Cryopreservation of red blood cells (RBCs) provides great potential benefits for providing transfusion timely in emergencies. High concentrations of glycerol (20% or 40%) are used for RBC cryopreservation in current clinical practice, which results in cytotoxicity and osmotic injuries that must be carefully controlled. However, existing studies on the low-glycerol cryopreservation of RBCs still suffer from the bottleneck of low hematocrit levels, which require relatively large storage space and an extra concentration process before transfusion, making it inconvenient (time-consuming, and also may cause injury and sample lose) for clinical applications. To this end, we develop a novel method for the glycerol-free cryopreservation of human RBCs with a high final hematocrit by using trehalose as the sole cryoprotectant to dehydrate RBCs and using core–shell alginate hydrogel microfibers to enhance heat transfer during cryopreservation. Different from previous studies, we achieve the cryopreservation of human RBCs at high hematocrit (> 40%) with high recovery (up to 95%). Additionally, the washed RBCs post-cryopreserved are proved to maintain their morphology, mechanics, and functional properties. This may provide a nontoxic, high-efficiency, and glycerol-free approach for RBC cryopreservation, along with potential clinical transfusion benefits.

Highlights:
1 We developed a novel method for high-efficiency, nontoxic, glycerol-free, scalable cryopreservation of human red blood cells with a high hematocrit (> 40%).
2 This method offered the potential for ultrafast and convenient applications by eliminating the need for permeable cryoprotectants, simplifying the washing steps, and reducing the washing time.
3 This method achieved a high RBC recovery of up to 95%, and the RBCs post-cryopreserved maintained their morphology, mechanics, and functional properties.

Layered Potassium Titanium Niobate/Reduced Graphene Oxide Nanocomposite as a Potassium-Ion Battery Anode

Mon, 13 Nov 2023 00:00:00 +0000

With graphite currently leading as the most viable anode for potassium-ion batteries (KIBs), other materials have been left relatively under-examined. Transition metal oxides are among these, with many positive attributes such as synthetic maturity, long-term cycling stability and fast redox kinetics. Therefore, to address this research deficiency we report herein a layered potassium titanium niobate KTiNbO₅ (KTNO) and its rGO nanocomposite (KTNO/rGO) synthesised via solvothermal methods as a high-performance anode for KIBs. Through effective distribution across the electrically conductive rGO, the electrochemical performance of the KTNO nanoparticles was enhanced. The potassium storage performance of the KTNO/rGO was demonstrated by its first charge capacity of 128.1 mAh g⁻¹ and reversible capacity of 97.5 mAh g⁻¹ after 500 cycles at 20 mA g⁻¹, retaining 76.1% of the initial capacity, with an exceptional rate performance of 54.2 mAh g⁻¹ at 1 A g⁻¹. Furthermore, to investigate the attributes of KTNO in-situ XRD was performed, indicating a low-strain material. Ex-situ X-ray photoelectron spectra further investigated the mechanism of charge storage, with the titanium showing greater redox reversibility than the niobium. This work suggests this low-strain nature is a highly advantageous property and well worth regarding KTNO as a promising anode for future high-performance KIBs.

Highlights:
1 KTiNbO₅ and KTiNbO₅/reduced graphene oxide (rGO) nanocomposites were successfully synthesised via solvothermal methods. Optimising the rGO wt% yielded a composite with 12 wt% (KTNO/rGO-12).
2 KTNO/rGO-12 was tested for its potassium storage performance, achieving a first charge capacity of 128.1 mAh g⁻¹ and retaining 76.1% over 500 cycles at 20 mAh g⁻¹.
3 The mechanism of intercalation was examined, suggesting a potentially low-strain material, with both titanium and niobium redox activity contributing to the charge storage.

Innovative Solutions for High-Performance Silicon Anodes in Lithium-Ion Batteries: Overcoming Challenges and Real-World Applications

Wed, 24 Apr 2024 00:00:00 +0000

Silicon (Si) has emerged as a potent anode material for lithium-ion batteries (LIBs), but faces challenges like low electrical conductivity and significant volume changes during lithiation/delithiation, leading to material pulverization and capacity degradation. Recent research on nanostructured Si aims to mitigate volume expansion and enhance electrochemical performance, yet still grapples with issues like pulverization, unstable solid electrolyte interface (SEI) growth, and interparticle resistance. This review delves into innovative strategies for optimizing Si anodes’ electrochemical performance via structural engineering, focusing on the synthesis of Si/C composites, engineering multidimensional nanostructures, and applying non-carbonaceous coatings. Forming a stable SEI is vital to prevent electrolyte decomposition and enhance Li⁺ transport, thereby stabilizing the Si anode interface and boosting cycling Coulombic efficiency. We also examine groundbreaking advancements such as self-healing polymers and advanced prelithiation methods to improve initial Coulombic efficiency and combat capacity loss. Our review uniquely provides a detailed examination of these strategies in real-world applications, moving beyond theoretical discussions. It offers a critical analysis of these approaches in terms of performance enhancement, scalability, and commercial feasibility. In conclusion, this review presents a comprehensive view and a forward-looking perspective on designing robust, high-performance Si-based anodes the next generation of LIBs.

Highlights:
1 Si/C Composite and Nanostructure Engineering: Advanced Si/C composites and multidimensional nanostructures address key challenges in silicon anodes, like volume expansion and unstable SEI, enhancing LIBs performance.
2 Artificial SEI, Prelithiation, and Binders: Focus on stable artificial SEI layers, efficient prelithiation, and cutting-edge binders to improve Coulombic efficiency and reduce capacity loss, enhancing Si anode durability and efficiency.
3 Real-World Application and Scalability: Analysis of these strategies highlights scalability and commercial viability, transitioning Si-anode technologies to practical, high-performance LIBs applications.

Advances in All-Solid-State Lithium–Sulfur Batteries for Commercialization

Mon, 15 Apr 2024 00:00:00 +0000

Solid-state batteries are commonly acknowledged as the forthcoming evolution in energy storage technologies. Recent development progress for these rechargeable batteries has notably accelerated their trajectory toward achieving commercial feasibility. In particular, all-solid-state lithium–sulfur batteries (ASSLSBs) that rely on lithium–sulfur reversible redox processes exhibit immense potential as an energy storage system, surpassing conventional lithium-ion batteries. This can be attributed predominantly to their exceptional energy density, extended operational lifespan, and heightened safety attributes. Despite these advantages, the adoption of ASSLSBs in the commercial sector has been sluggish. To expedite research and development in this particular area, this article provides a thorough review of the current state of ASSLSBs. We delve into an in-depth analysis of the rationale behind transitioning to ASSLSBs, explore the fundamental scientific principles involved, and provide a comprehensive evaluation of the main challenges faced by ASSLSBs. We suggest that future research in this field should prioritize plummeting the presence of inactive substances, adopting electrodes with optimum performance, minimizing interfacial resistance, and designing a scalable fabrication approach to facilitate the commercialization of ASSLSBs.

Highlights:
1 Challenges in developing practical all-solid-state lithium–sulfur batteries (ASSLSBs) and recently devised concepts to address those critical challenges have been discussed.
2 Recent developments in comprehending solid-state electrolytes, cathodes, and highperformance anodes, including key challenges associated with ion transport, electrochemical properties, and processing methods, have been discussed.
3 Prospects of ASSLSBs for commercial use and guiding forthcoming research and development efforts in this area have been presented.

Synthesis and Modulation of Low-Dimensional Transition Metal Chalcogenide Materials via Atomic Substitution

Xuan Wang, Akang Chen, XinLei Wu, Jiatao Zhang, Jichen Dong, Leining Zhang — Thu, 28 Mar 2024 00:00:00 +0000

In recent years, low-dimensional transition metal chalcogenide (TMC) materials have garnered growing research attention due to their superior electronic, optical, and catalytic properties compared to their bulk counterparts. The controllable synthesis and manipulation of these materials are crucial for tailoring their properties and unlocking their full potential in various applications. In this context, the atomic substitution method has emerged as a favorable approach. It involves the replacement of specific atoms within TMC structures with other elements and possesses the capability to regulate the compositions finely, crystal structures, and inherent properties of the resulting materials. In this review, we present a comprehensive overview on various strategies of atomic substitution employed in the synthesis of zero-dimensional, one-dimensional and two-dimensional TMC materials. The effects of substituting elements, substitution ratios, and substitution positions on the structures and morphologies of resulting material are discussed. The enhanced electrocatalytic performance and photovoltaic properties of the obtained materials are also provided, emphasizing the role of atomic substitution in achieving these advancements. Finally, challenges and future prospects in the field of atomic substitution for fabricating low-dimensional TMC materials are summarized.

Highlights:
1 Atomic substitution applied in the synthesis of different dimensional transition metal chalcogenide (TMC) is dissertated.
2 The controllable synthesis and property modification realization with atomic substitution or ion exchange are introduced.
3 The substitution principle and mechanism in different TMCs are concluded.

Design Principles and Mechanistic Understandings of Non-Noble-Metal Bifunctional Electrocatalysts for Zinc–Air Batteries

Tue, 26 Mar 2024 00:00:00 +0000

Zinc–air batteries (ZABs) are promising energy storage systems because of high theoretical energy density, safety, low cost, and abundance of zinc. However, the slow multi-step reaction of oxygen and heavy reliance on noble-metal catalysts hinder the practical applications of ZABs. Therefore, feasible and advanced non-noble-metal electrocatalysts for air cathodes need to be identified to promote the oxygen catalytic reaction. In this review, we initially introduced the advancement of ZABs in the past two decades and provided an overview of key developments in this field. Then, we discussed the working mechanism and the design of bifunctional electrocatalysts from the perspective of morphology design, crystal structure tuning, interface strategy, and atomic engineering. We also included theoretical studies, machine learning, and advanced characterization technologies to provide a comprehensive understanding of the structure-performance relationship of electrocatalysts and the reaction pathways of the oxygen redox reactions. Finally, we discussed the challenges and prospects related to designing advanced non-noble-metal bifunctional electrocatalysts for ZABs.

Highlights:
1 The recent advances in non-noble-metal bifunctional electrocatalysts for zinc–air batteries are summarized with the design principles.
2 The working mechanism are discussed to provide a comprehensive understanding of the structure-performance relationship of electrocatalysts and the reaction pathways of the oxygen redox reactions.
3 The challenges and prospects related to designing advanced non-noble-metal bifunctional electrocatalysts for high performance zinc–air batteries are provided.

Challenges and Opportunities in Preserving Key Structural Features of 3D-Printed Metal/Covalent Organic Framework

Ximeng Liu, Dan Zhao, John Wang — Thu, 21 Mar 2024 00:00:00 +0000

Metal–organic framework (MOF) and covalent organic framework (COF) are a huge group of advanced porous materials exhibiting attractive and tunable microstructural features, such as large surface area, tunable pore size, and functional surfaces, which have significant values in various application areas. The emerging 3D printing technology further provides MOF and COFs (M/COFs) with higher designability of their macrostructure and demonstrates large achievements in their performance by shaping them into advanced 3D monoliths. However, the currently available 3D printing M/COFs strategy faces a major challenge of severe destruction of M/COFs’ microstructural features, both during and after 3D printing. It is envisioned that preserving the microstructure of M/COFs in the 3D-printed monolith will bring a great improvement to the related applications. In this overview, the 3D-printed M/COFs are categorized into M/COF-mixed monoliths and M/COF-covered monoliths. Their differences in the properties, applications, and current research states are discussed. The up-to-date advancements in paste/scaffold composition and printing/covering methods to preserve the superior M/COF microstructure during 3D printing are further discussed for the two types of 3D-printed M/COF. Throughout the analysis of the current states of 3D-printed M/COFs, the expected future research direction to achieve a highly preserved microstructure in the 3D monolith is proposed.

Highlights:
1 A comprehensive investigation on the research states of 3D-printed metal/covalent organic frameworks (M/COFs) is conducted with the discussion on the M/COF-mixed monolith and M/COF-covered monolith separately.
2 Recent advances in design strategies regarding both the paste/scaffold formation and the 3D-printing/covering process for preserving the better structural features of M/COFs (surface area, porosity, and micromorphology) in their 3D printed monolith are overviewed and discussed.

Collective Molecular Machines: Multidimensionality and Reconfigurability

Bin Wang, Yuan Lu — Mon, 18 Mar 2024 00:00:00 +0000

Molecular machines are key to cellular activity where they are involved in converting chemical and light energy into efficient mechanical work. During the last 60 years, designing molecular structures capable of generating unidirectional mechanical motion at the nanoscale has been the topic of intense research. Effective progress has been made, attributed to advances in various fields such as supramolecular chemistry, biology and nanotechnology, and informatics. However, individual molecular machines are only capable of producing nanometer work and generally have only a single functionality. In order to address these problems, collective behaviors realized by integrating several or more of these individual mechanical units in space and time have become a new paradigm. In this review, we comprehensively discuss recent developments in the collective behaviors of molecular machines. In particular, collective behavior is divided into two paradigms. One is the appropriate integration of molecular machines to efficiently amplify molecular motions and deformations to construct novel functional materials. The other is the construction of swarming modes at the supramolecular level to perform nanoscale or microscale operations. We discuss design strategies for both modes and focus on the modulation of features and properties. Subsequently, in order to address existing challenges, the idea of transferring experience gained in the field of micro/nano robotics is presented, offering prospects for future developments in the collective behavior of molecular machines.

Highlights:
1 Recent advances and design strategies for molecular machines working as collectives in building smart responsive materials and micro/nanoscale operations are summarized in this review.
2 The modulation of collective behaviors characteristics and properties is summarized in focus, including reversibility, amplification, anisotropy and reconfigurability of smart materials, as well as reconfigurability, orthogonality and logical control of swarming.
3 Experiences and paradigms in the field of micro/nanorobotics in collective construction, control strategies, and model transformations are expected to provide guidance for molecular machines to build reconfigurable, multi-dimensional, and multi-modularity advanced collectives.

Functional Optical Fiber Sensors Detecting Imperceptible Physical/Chemical Changes for Smart Batteries

Yiding Li, Li Wang, Youzhi Song, Wenwei Wang, Cheng Lin, Xiangming He — Mon, 18 Mar 2024 00:00:00 +0000

The battery technology progress has been a contradictory process in which performance improvement and hidden risks coexist. Now the battery is still a “black box”, thus requiring a deep understanding of its internal state. The battery should “sense its internal physical/chemical conditions”, which puts strict requirements on embedded sensing parts. This paper summarizes the application of advanced optical fiber sensors in lithium-ion batteries and energy storage technologies that may be mass deployed, focuses on the insights of advanced optical fiber sensors into the processes of one-dimensional nano–micro-level battery material structural phase transition, electrolyte degradation, electrode–electrolyte interface dynamics to three-dimensional macro-safety evolution. The paper contributes to understanding how to use optical fiber sensors to achieve “real” and “embedded” monitoring. Through the inherent advantages of the advanced optical fiber sensor, it helps clarify the battery internal state and reaction mechanism, aiding in the establishment of more detailed models. These advancements can promote the development of smart batteries, with significant importance lying in essentially promoting the improvement of system consistency. Furthermore, with the help of smart batteries in the future, the importance of consistency can be weakened or even eliminated. The application of advanced optical fiber sensors helps comprehensively improve the battery quality, reliability, and life.

Highlights:
1 Research progress of advanced optical fiber sensors in traction batteries and energy storage batteries is summarized.
2 The embedded application mechanisms of different optical fiber sensors in batteries are discussed.
3 Advanced optical fiber sensors adapting to batteries with diverse materials are reviewed.
4 Advanced optical fiber sensors driving the development of future smart batteries are prospected.

Personal Thermal Management by Radiative Cooling and Heating

Shidong Xue, Guanghan Huang, Qing Chen, Xungai Wang, Jintu Fan, Dahua Shou — Wed, 13 Mar 2024 00:00:00 +0000

Maintaining thermal comfort within the human body is crucial for optimal health and overall well-being. By merely broadening the set-point of indoor temperatures, we could significantly slash energy usage in building heating, ventilation, and air-conditioning systems. In recent years, there has been a surge in advancements in personal thermal management (PTM), aiming to regulate heat and moisture transfer within our immediate surroundings, clothing, and skin. The advent of PTM is driven by the rapid development in nano/micro-materials and energy science and engineering. An emerging research area in PTM is personal radiative thermal management (PRTM), which demonstrates immense potential with its high radiative heat transfer efficiency and ease of regulation. However, it is less taken into account in traditional textiles, and there currently lies a gap in our knowledge and understanding of PRTM. In this review, we aim to present a thorough analysis of advanced textile materials and technologies for PRTM. Specifically, we will introduce and discuss the underlying radiation heat transfer mechanisms, fabrication methods of textiles, and various indoor/outdoor applications in light of their different regulation functionalities, including radiative cooling, radiative heating, and dual-mode thermoregulation. Furthermore, we will shine a light on the current hurdles, propose potential strategies, and delve into future technology trends for PRTM with an emphasis on functionalities and applications.

Highlights:
1 This review delves into the intricate relationship between thermal models, function-oriented design principles, and practical applications in personal radiative thermal management (PRTM).
2 It provides an in-depth discussion on design strategies for radiative cooling, heating, and dual-mode modulating textiles, offering practical insights for application.
3 It offers a thorough examination of the prospects and challenges of PRTM textiles, proposing potential solutions and future directions for the field.

Structural Engineering of Anode Materials for Low-Temperature Lithium-Ion Batteries: Mechanisms, Strategies, and Prospects

Guan Wang, Guixin Wang, Linfeng Fei, Lina Zhao, Haitao Zhang — Mon, 11 Mar 2024 00:00:00 +0000

The severe degradation of electrochemical performance for lithium-ion batteries (LIBs) at low temperatures poses a significant challenge to their practical applications. Consequently, extensive efforts have been contributed to explore novel anode materials with high electronic conductivity and rapid Li⁺ diffusion kinetics for achieving favorable low-temperature performance of LIBs. Herein, we try to review the recent reports on the synthesis and characterizations of low-temperature anode materials. First, we summarize the underlying mechanisms responsible for the performance degradation of anode materials at subzero temperatures. Second, detailed discussions concerning the key pathways (boosting electronic conductivity, enhancing Li⁺ diffusion kinetics, and inhibiting lithium dendrite) for improving the low-temperature performance of anode materials are presented. Third, several commonly used low-temperature anode materials are briefly introduced. Fourth, recent progress in the engineering of these low-temperature anode materials is summarized in terms of structural design, morphology control, surface & interface modifications, and multiphase materials. Finally, the challenges that remain to be solved in the field of low-temperature anode materials are discussed. This review was organized to offer valuable insights and guidance for next-generation LIBs with excellent low-temperature electrochemical performance.

Highlights:
1 The working principles and limitations of current anode materials at low temperatures are elucidated.
2 Advantages and emphases of various modification strategies, including structural design, morphology control, surface & interface modifications, and multiphase materials of low-temperature anode materials, are reviewed.
3 Perspectives and challenges in developing novel low-temperature anode materials are discussed.

Recent Progress in Improving Rate Performance of Cellulose-Derived Carbon Materials for Sodium-Ion Batteries

Fujuan Wang, Tianyun Zhang, Tian Zhang, Tianqi He, Fen Ran — Mon, 11 Mar 2024 00:00:00 +0000

Cellulose-derived carbon is regarded as one of the most promising candidates for high-performance anode materials in sodium-ion batteries; however, its poor rate performance at higher current density remains a challenge to achieve high power density sodium-ion batteries. The present review comprehensively elucidates the structural characteristics of cellulose-based materials and cellulose-derived carbon materials, explores the limitations in enhancing rate performance arising from ion diffusion and electronic transfer at the level of cellulose-derived carbon materials, and proposes corresponding strategies to improve rate performance targeted at various precursors of cellulose-based materials. This review also presents an update on recent progress in cellulose-based materials and cellulose-derived carbon materials, with particular focuses on their molecular, crystalline, and aggregation structures. Furthermore, the relationship between storage sodium and rate performance the carbon materials is elucidated through theoretical calculations and characterization analyses. Finally, future perspectives regarding challenges and opportunities in the research field of cellulose-derived carbon anodes are briefly highlighted.

Highlights:
1 Enhancing rate performance of cellulose-derived hard carbon anodes from the view of cellulose molecular, crystalline, and aggregation structure is explored.
2 Relationship of storage sodium and rate performance according to theoretical calculation and characterization analysis is illustrated.
3 Cellulose intrinsic microstructure, conversion relationship between the allotropes of cellulose, and the critical influences on cellulose-derived carbon structure are discussed.

Nano/Micro-Structural Supramolecular Biopolymers: Innovative Networks with the Boundless Potential in Sustainable Agriculture

Fri, 08 Mar 2024 00:00:00 +0000

Sustainable agriculture plays a crucial role in meeting the growing global demand for food while minimizing adverse environmental impacts from the overuse of synthetic pesticides and conventional fertilizers. In this context, renewable biopolymers being more sustainable offer a viable solution to improve agricultural sustainability and production. Nano/micro-structural supramolecular biopolymers are among these innovative biopolymers that are much sought after for their unique features. These biomaterials have complex hierarchical structures, great stability, adjustable mechanical strength, stimuli-responsiveness, and self-healing attributes. Functional molecules may be added to their flexible structure, for enabling novel agricultural uses. This overview scrutinizes how nano/micro-structural supramolecular biopolymers may radically alter farming practices and solve lingering problems in agricultural sector namely improve agricultural production, soil health, and resource efficiency. Controlled bioactive ingredient released from biopolymers allows the tailored administration of agrochemicals, bioactive agents, and biostimulators as they enhance nutrient absorption, moisture retention, and root growth. Nano/micro-structural supramolecular biopolymers may protect crops by appending antimicrobials and biosensing entities while their eco-friendliness supports sustainable agriculture. Despite their potential, further studies are warranted to understand and optimize their usage in agricultural domain. This effort seeks to bridge the knowledge gap by investigating their applications, challenges, and future prospects in the agricultural sector. Through experimental investigations and theoretical modeling, this overview aims to provide valuable insights into the practical implementation and optimization of supramolecular biopolymers in sustainable agriculture, ultimately contributing to the development of innovative and eco-friendly solutions to enhance agricultural productivity while minimizing environmental impact.

Highlights:
1 Safer and biodegradable nano/micro-supramolecular biopolymers transform farming practices.
2 Supramolecular biopolymers improve soil structure, water retention, and plant nutrient uptake.
3 Encapsulation of bioactive compounds and their controlled release by nano/micro-supramolecular biopolymers enables targeted delivery.
4 Biopolymer networks can potentially be embedded in biosensors for crop protection goals.

Current Status and Perspectives of Dual-Atom Catalysts Towards Sustainable Energy Utilization

Thu, 29 Feb 2024 00:00:00 +0000

The exploration of sustainable energy utilization requires the implementation of advanced electrochemical devices for efficient energy conversion and storage, which are enabled by the usage of cost-effective, high-performance electrocatalysts. Currently, heterogeneous atomically dispersed catalysts are considered as potential candidates for a wide range of applications. Compared to conventional catalysts, atomically dispersed metal atoms in carbon-based catalysts have more unsaturated coordination sites, quantum size effect, and strong metal–support interactions, resulting in exceptional catalytic activity. Of these, dual-atomic catalysts (DACs) have attracted extensive attention due to the additional synergistic effect between two adjacent metal atoms. DACs have the advantages of full active site exposure, high selectivity, theoretical 100% atom utilization, and the ability to break the scaling relationship of adsorption free energy on active sites. In this review, we summarize recent research advancement of DACs, which includes (1) the comprehensive understanding of the synergy between atomic pairs; (2) the synthesis of DACs; (3) characterization methods, especially aberration-corrected scanning transmission electron microscopy and synchrotron spectroscopy; and (4) electrochemical energy-related applications. The last part focuses on great potential for the electrochemical catalysis of energy-related small molecules, such as oxygen reduction reaction, CO₂ reduction reaction, hydrogen evolution reaction, and N₂ reduction reaction. The future research challenges and opportunities are also raised in prospective section.

Highlights:
1 The advancement and current status of dual-atom catalysts are reported.
2 The synergistic effects exhibited by recent dual-atom catalysts in mechanistic studies are classified and summarized.
3 Challenges and prospects of dual-atom catalysts in synthesis, characterization, applications, and theory are discussed.

A Review of Rechargeable Zinc–Air Batteries: Recent Progress and Future Perspectives

Thu, 29 Feb 2024 00:00:00 +0000

Zinc–air batteries (ZABs) are gaining attention as an ideal option for various applications requiring high-capacity batteries, such as portable electronics, electric vehicles, and renewable energy storage. ZABs offer advantages such as low environmental impact, enhanced safety compared to Li-ion batteries, and cost-effectiveness due to the abundance of zinc. However, early research faced challenges due to parasitic reactions at the zinc anode and slow oxygen redox kinetics. Recent advancements in restructuring the anode, utilizing alternative electrolytes, and developing bifunctional oxygen catalysts have significantly improved ZABs. Scientists have achieved battery reversibility over thousands of cycles, introduced new electrolytes, and achieved energy efficiency records surpassing 70%. Despite these achievements, there are challenges related to lower power density, shorter lifespan, and air electrode corrosion leading to performance degradation. This review paper discusses different battery configurations, and reaction mechanisms for electrically and mechanically rechargeable ZABs, and proposes remedies to enhance overall battery performance. The paper also explores recent advancements, applications, and the future prospects of electrically/mechanically rechargeable ZABs.

Highlights:
1 Recent progress in Zn–air batteries is critically reviewed.
2 Current challenges of rechargeable Zn–air batteries are highlighted.
3 Strategies for the advancement of the anode, electrolyte, and oxygen catalyst are discussed.
4 Future research directions are provided to design commercial Zn–air batteries.

MXene-Based Elastomer Mimetic Stretchable Sensors: Design, Properties, and Applications

Tue, 27 Feb 2024 00:00:00 +0000

Flexible sensors based on MXene-polymer composites are highly prospective for next-generation wearable electronics used in human–machine interfaces. One of the motivating factors behind the progress of flexible sensors is the steady arrival of new conductive materials. MXenes, a new family of 2D nanomaterials, have been drawing attention since the last decade due to their high electronic conductivity, processability, mechanical robustness and chemical tunability. In this review, we encompass the fabrication of MXene-based polymeric nanocomposites, their structure–property relationship, and applications in the flexible sensor domain. Moreover, our discussion is not only limited to sensor design, their mechanism, and various modes of sensing platform, but also their future perspective and market throughout the world. With our article, we intend to fortify the bond between flexible matrices and MXenes thus promoting the swift advancement of flexible MXene-sensors for wearable technologies.

Highlights:
1 MXenes, a new family of 2D nanomaterials, have been drawing notable attention due to their high electrical conductivity, processability, mechanical robustness and chemical tunability.
2 Flexible sensors based on MXene-polymer composites are highly prospective for next-generation wearable electronics used in human–machine interfaces.
3 With our article, we intend to fortify the bond between flexible matrices and MXenes thus promoting the swift advancement of flexible MXene-sensors for wearable technologies.

Active Micro-Nano-Collaborative Bioelectronic Device for Advanced Electrophysiological Recording

Tue, 27 Feb 2024 00:00:00 +0000

The development of precise and sensitive electrophysiological recording platforms holds the utmost importance for research in the fields of cardiology and neuroscience. In recent years, active micro/nano-bioelectronic devices have undergone significant advancements, thereby facilitating the study of electrophysiology. The distinctive configuration and exceptional functionality of these active micro-nano-collaborative bioelectronic devices offer the potential for the recording of high-fidelity action potential signals on a large scale. In this paper, we review three-dimensional active nano-transistors and planar active micro-transistors in terms of their applications in electro-excitable cells, focusing on the evaluation of the effects of active micro/nano-bioelectronic devices on electrophysiological signals. Looking forward to the possibilities, challenges, and wide prospects of active micro-nano-devices, we expect to advance their progress to satisfy the demands of theoretical investigations and medical implementations within the domains of cardiology and neuroscience research.

Highlights:
1 The factors affecting electrophysiological recordings from active micro-nano-collaborative bioelectronic devices were discussed in terms of principle and fabrication.
2 An overview of the applications of active micro-nano-collaborative bioelectronic devices in cardiomyocytes and neurons was further presented.
3 The challenges faced by active micro-nano-collaborative bioelectronic devices in intracellular electrophysiological studies and their prospective biomedical applications are discussed.

Insights into Nano- and Micro-Structured Scaffolds for Advanced Electrochemical Energy Storage

Jiajia Qiu, Yu Duan, Shaoyuan Li, Huaping Zhao, Wenhui Ma, Weidong Shi, Yong Lei — Fri, 23 Feb 2024 00:00:00 +0000

Adopting a nano- and micro-structuring approach to fully unleashing the genuine potential of electrode active material benefits in-depth understandings and research progress toward higher energy density electrochemical energy storage devices at all technology readiness levels. Due to various challenging issues, especially limited stability, nano- and micro-structured (NMS) electrodes undergo fast electrochemical performance degradation. The emerging NMS scaffold design is a pivotal aspect of many electrodes as it endows them with both robustness and electrochemical performance enhancement, even though it only occupies complementary and facilitating components for the main mechanism. However, extensive efforts are urgently needed toward optimizing the stereoscopic geometrical design of NMS scaffolds to minimize the volume ratio and maximize their functionality to fulfill the ever-increasing dependency and desire for energy power source supplies. This review will aim at highlighting these NMS scaffold design strategies, summarizing their corresponding strengths and challenges, and thereby outlining the potential solutions to resolve these challenges, design principles, and key perspectives for future research in this field. Therefore, this review will be one of the earliest reviews from this viewpoint.

Highlights:
1 Recent advances in electrochemical energy storage based on nano- and micro-structured (NMS) scaffolds are summarized and discussed.
2 The fundamentals, superiorities, and design principle of NMS scaffolds are outlined.
3 Given the present progress, the ongoing challenges and promising perspectives are highlighted.

Progress on Transition Metal Ions Dissolution Suppression Strategies in Prussian Blue Analogs for Aqueous Sodium-/Potassium-Ion Batteries

Wenli Shu, Junxian Li, Guangwan Zhang, Jiashen Meng, Xuanpeng Wang, Liqiang Mai — Wed, 21 Feb 2024 00:00:00 +0000

Aqueous sodium-ion batteries (ASIBs) and aqueous potassium-ion batteries (APIBs) present significant potential for large-scale energy storage due to their cost-effectiveness, safety, and environmental compatibility. Nonetheless, the intricate energy storage mechanisms in aqueous electrolytes place stringent requirements on the host materials. Prussian blue analogs (PBAs), with their open three-dimensional framework and facile synthesis, stand out as leading candidates for aqueous energy storage. However, PBAs possess a swift capacity fade and limited cycle longevity, for their structural integrity is compromised by the pronounced dissolution of transition metal (TM) ions in the aqueous milieu. This manuscript provides an exhaustive review of the recent advancements concerning PBAs in ASIBs and APIBs. The dissolution mechanisms of TM ions in PBAs, informed by their structural attributes and redox processes, are thoroughly examined. Moreover, this study delves into innovative design tactics to alleviate the dissolution issue of TM ions. In conclusion, the paper consolidates various strategies for suppressing the dissolution of TM ions in PBAs and posits avenues for prospective exploration of high-safety aqueous sodium-/potassium-ion batteries.

Highlights:
1 Comprehensive insights into Prussian blue analogs for aqueous sodium- and potassium-ion batteries.
2 Unveiling the dissolution mechanism of transition metal ions in Prussian blue analogs.
3 Innovative solutions to suppression transition metal ion dissolution, spanning electrolyte engineering, transition metal doping/substitution, minimize defects, and composite materials.

PDOL-Based Solid Electrolyte Toward Practical Application: Opportunities and Challenges

Hua Yang, Maoxiang Jing, Li Wang, Hong Xu, Xiaohong Yan, Xiangming He — Wed, 21 Feb 2024 00:00:00 +0000

Polymer solid-state lithium batteries (SSLB) are regarded as a promising energy storage technology to meet growing demand due to their high energy density and safety. Ion conductivity, interface stability and battery assembly process are still the main challenges to hurdle the commercialization of SSLB. As the main component of SSLB, poly(1,3-dioxolane) (PDOL)-based solid polymer electrolytes polymerized in-situ are becoming a promising candidate solid electrolyte, for their high ion conductivity at room temperature, good battery electrochemical performances, and simple assembly process. This review analyzes opportunities and challenges of PDOL electrolytes toward practical application for polymer SSLB. The focuses include exploring the polymerization mechanism of DOL, the performance of PDOL composite electrolytes, and the application of PDOL. Furthermore, we provide a perspective on future research directions that need to be emphasized for commercialization of PDOL-based electrolytes in SSLB. The exploration of these schemes facilitates a comprehensive and profound understanding of PDOL-based polymer electrolyte and provides new research ideas to boost them toward practical application in solid-state batteries.

Highlights:
1 The poly(1,3-dioxolane) (PDOL) electrolyte demonstrates promising potential for practical application due to its advantages in in-situ polymerization process, high ionic conductivity, and long cycle life.
2 This review focuses on the polymerization mechanism, composite innovation, and application of PDOL electrolytes.
3 This review provides a comprehensive summary of the challenges associated with the PDOL electrolyte and makes forward-looking recommendations.

Recent Advances in Mechanistic Understanding of Metal-Free Carbon Thermocatalysis and Electrocatalysis with Model Molecules

Wei Guo, Linhui Yu, Ling Tang, Yan Wan, Yangming Lin — Tue, 20 Feb 2024 00:00:00 +0000

Metal-free carbon, as the most representative heterogeneous metal-free catalysts, have received considerable interests in electro- and thermo-catalytic reactions due to their impressive performance and sustainability. Over the past decade, well-designed carbon catalysts with tunable structures and heteroatom groups coupled with various characterization techniques have proposed numerous reaction mechanisms. However, active sites, key intermediate species, precise structure–activity relationships and dynamic evolution processes of carbon catalysts are still rife with controversies due to the monotony and limitation of used experimental methods. In this Review, we summarize the extensive efforts on model catalysts since the 2000s, particularly in the past decade, to overcome the influences of material and structure limitations in metal-free carbon catalysis. Using both nanomolecule model and bulk model, the real contribution of each alien species, defect and edge configuration to a series of fundamentally important reactions, such as thermocatalytic reactions, electrocatalytic reactions, were systematically studied. Combined with in situ techniques, isotope labeling and size control, the detailed reaction mechanisms, the precise 2D structure–activity relationships and the rate-determining steps were revealed at a molecular level. Furthermore, the outlook of model carbon catalysis has also been proposed in this work.

Highlights:
1 Mechanistic understandings of metal-free carbon thermocatalysis and electrocatalysis from the viewpoint of model method are summarized.
2 Active sites and reaction mechanisms are discussed with a focus on in-situ techniques and 2D structure–activity relationships.
3 The real contribution of each alien species, defect and edge configuration to catalytic reactions are systematically highlighted at a molecular level.

Recent Advances in In-Memory Computing: Exploring Memristor and Memtransistor Arrays with 2D Materials

Hangbo Zhou, Sifan Li, Kah‑Wee Ang, Yong‑Wei Zhang — Mon, 19 Feb 2024 00:00:00 +0000

The conventional computing architecture faces substantial challenges, including high latency and energy consumption between memory and processing units. In response, in-memory computing has emerged as a promising alternative architecture, enabling computing operations within memory arrays to overcome these limitations. Memristive devices have gained significant attention as key components for in-memory computing due to their high-density arrays, rapid response times, and ability to emulate biological synapses. Among these devices, two-dimensional (2D) material-based memristor and memtransistor arrays have emerged as particularly promising candidates for next-generation in-memory computing, thanks to their exceptional performance driven by the unique properties of 2D materials, such as layered structures, mechanical flexibility, and the capability to form heterojunctions. This review delves into the state-of-the-art research on 2D material-based memristive arrays, encompassing critical aspects such as material selection, device performance metrics, array structures, and potential applications. Furthermore, it provides a comprehensive overview of the current challenges and limitations associated with these arrays, along with potential solutions. The primary objective of this review is to serve as a significant milestone in realizing next-generation in-memory computing utilizing 2D materials and bridge the gap from single-device characterization to array-level and system-level implementations of neuromorphic computing, leveraging the potential of 2D material-based memristive devices.

Highlights:
1 State-of-the-art research on two-dimensional material-based memristive arrays is comprehensively reviewed.
2 Critical steps in achieving in-memory computing are identified and highlighted, covering material selection, device performance analysis, and array structure design.
3 Challenges in progressing from single-device characterization to array-level and system-level implementations are discussed, along with proposed solutions.

The Roadmap of 2D Materials and Devices Toward Chips

Fri, 16 Feb 2024 00:00:00 +0000

Due to the constraints imposed by physical effects and performance degradation, silicon-based chip technology is facing certain limitations in sustaining the advancement of Moore’s law. Two-dimensional (2D) materials have emerged as highly promising candidates for the post-Moore era, offering significant potential in domains such as integrated circuits and next-generation computing. Here, in this review, the progress of 2D semiconductors in process engineering and various electronic applications are summarized. A careful introduction of material synthesis, transistor engineering focused on device configuration, dielectric engineering, contact engineering, and material integration are given first. Then 2D transistors for certain electronic applications including digital and analog circuits, heterogeneous integration chips, and sensing circuits are discussed. Moreover, several promising applications (artificial intelligence chips and quantum chips) based on specific mechanism devices are introduced. Finally, the challenges for 2D materials encountered in achieving circuit-level or system-level applications are analyzed, and potential development pathways or roadmaps are further speculated and outlooked.

Highlights:
1 This review introduces the potential of 2D electronics for post-Moore era and discusses their current progress in digital circuits, analog circuits, heterogeneous integration, sensing circuits, artificial intelligence chips, and quantum chips in sequence.
2 A comprehensive analysis of the current trends and challenges encountered in the development of 2D materials is summarized.
3 An in-depth roadmap outlining the future development of 2D electronics is presented, and the most accessible and promising avenues for 2D electronics are suggested.

Highly Aligned Graphene Aerogels for Multifunctional Composites

Thu, 15 Feb 2024 00:00:00 +0000

Stemming from the unique in-plane honeycomb lattice structure and the sp² hybridized carbon atoms bonded by exceptionally strong carbon–carbon bonds, graphene exhibits remarkable anisotropic electrical, mechanical, and thermal properties. To maximize the utilization of graphene's in-plane properties, pre-constructed and aligned structures, such as oriented aerogels, films, and fibers, have been designed. The unique combination of aligned structure, high surface area, excellent electrical conductivity, mechanical stability, thermal conductivity, and porous nature of highly aligned graphene aerogels allows for tailored and enhanced performance in specific directions, enabling advancements in diverse fields. This review provides a comprehensive overview of recent advances in highly aligned graphene aerogels and their composites. It highlights the fabrication methods of aligned graphene aerogels and the optimization of alignment which can be estimated both qualitatively and quantitatively. The oriented scaffolds endow graphene aerogels and their composites with anisotropic properties, showing enhanced electrical, mechanical, and thermal properties along the alignment at the sacrifice of the perpendicular direction. This review showcases remarkable properties and applications of aligned graphene aerogels and their composites, such as their suitability for electronics, environmental applications, thermal management, and energy storage. Challenges and potential opportunities are proposed to offer new insights into prospects of this material.

Highlights:
1 Aligned graphene building blocks take full advantages of the outstanding properties of graphene.
2 Comprehensive review of recent advancements in the utilization of highly aligned graphene aerogels for multifunctional applications.
3 By systematically summarizing the controlled assembly, aligned structural attributes, quantitative characterization methods, anisotropic properties, and multifunctional applications of graphene aerogels, this review enhances understanding of the material's potential for diverse applications, offering tailored properties and novel functionalities.

Nanozyme-Engineered Hydrogels for Anti-Inflammation and Skin Regeneration

Amal George Kurian, Rajendra K. Singh, Varsha Sagar, Jung‑Hwan Lee, Hae‑Won Kim — Tue, 06 Feb 2024 00:00:00 +0000

Inflammatory skin disorders can cause chronic scarring and functional impairments, posing a significant burden on patients and the healthcare system. Conventional therapies, such as corticosteroids and nonsteroidal anti-inflammatory drugs, are limited in efficacy and associated with adverse effects. Recently, nanozyme (NZ)-based hydrogels have shown great promise in addressing these challenges. NZ-based hydrogels possess unique therapeutic abilities by combining the therapeutic benefits of redox nanomaterials with enzymatic activity and the water-retaining capacity of hydrogels. The multifaceted therapeutic effects of these hydrogels include scavenging reactive oxygen species and other inflammatory mediators modulating immune responses toward a pro-regenerative environment and enhancing regenerative potential by triggering cell migration and differentiation. This review highlights the current state of the art in NZ-engineered hydrogels (NZ@hydrogels) for anti-inflammatory and skin regeneration applications. It also discusses the underlying chemo-mechano-biological mechanisms behind their effectiveness. Additionally, the challenges and future directions in this ground, particularly their clinical translation, are addressed. The insights provided in this review can aid in the design and engineering of novel NZ-based hydrogels, offering new possibilities for targeted and personalized skin-care therapies.

Highlights:
1 Nanozyme-based approaches to produce therapeutic hydrogels.
2 Enzymatic mechanisms and multifunctional roles of nanozyme-engineered hydrogels for skin therapy.
3 Therapeutic actions of nanozyme-engineered hydrogels in inflamed skin tissues.
4 Mechanical and immunological aspects of skin therapy guided by nanozyme-engineered hydrogels.
5 Promising directions and challenges of nanozyme-inspired hydrogel platforms.

A Review on Engineering Transition Metal Compound Catalysts to Accelerate the Redox Kinetics of Sulfur Cathodes for Lithium–Sulfur Batteries

Mon, 29 Jan 2024 00:00:00 +0000

Engineering transition metal compounds (TMCs) catalysts with excellent adsorption-catalytic ability has been one of the most effective strategies to accelerate the redox kinetics of sulfur cathodes. Herein, this review focuses on engineering TMCs catalysts by cation doping/anion doping/dual doping, bimetallic/bi-anionic TMCs, and TMCs-based heterostructure composites. It is obvious that introducing cations/anions to TMCs or constructing heterostructure can boost adsorption-catalytic capacity by regulating the electronic structure including energy band, d/p-band center, electron filling, and valence state. Moreover, the electronic structure of doped/dual-ionic TMCs are adjusted by inducing ions with different electronegativity, electron filling, and ion radius, resulting in electron redistribution, bonds reconstruction, induced vacancies due to the electronic interaction and changed crystal structure such as lattice spacing and lattice distortion. Different from the aforementioned two strategies, heterostructures are constructed by two types of TMCs with different Fermi energy levels, which causes built-in electric field and electrons transfer through the interface, and induces electron redistribution and arranged local atoms to regulate the electronic structure. Additionally, the lacking studies of the three strategies to comprehensively regulate electronic structure for improving catalytic performance are pointed out. It is believed that this review can guide the design of advanced TMCs catalysts for boosting redox of lithium sulfur batteries.

Highlights:
1 The representatively engineering strategies of cations/anions doping, bimetallic/bi-anionic transition metal compounds and heterostructure composites catalysts for lithium sulfur batteries are comprehensively reviewed.
2 The promoted mechanism of catalytic performance by regulating electronic structure is focused on, including energy band, electron filling, d/p-band center, valence state.
3 The superiority of the modified transition metal compounds is comprehensively summarized.

Atomically Substitutional Engineering of Transition Metal Dichalcogenide Layers for Enhancing Tailored Properties and Superior Applications

Zhaosu Liu, Si Yin Tee, Guijian Guan, Ming‑Yong Han — Tue, 23 Jan 2024 00:00:00 +0000

Transition metal dichalcogenides (TMDs) are a promising class of layered materials in the post-graphene era, with extensive research attention due to their diverse alternative elements and fascinating semiconductor behavior. Binary MX₂ layers with different metal and/or chalcogen elements have similar structural parameters but varied optoelectronic properties, providing opportunities for atomically substitutional engineering via partial alteration of metal or/and chalcogenide atoms to produce ternary or quaternary TMDs. The resulting multinary TMD layers still maintain structural integrity and homogeneity while achieving tunable (opto)electronic properties across a full range of composition with arbitrary ratios of introduced metal or chalcogen to original counterparts (0–100%). Atomic substitution in TMD layers offers new adjustable degrees of freedom for tailoring crystal phase, band alignment/structure, carrier density, and surface reactive activity, enabling novel and promising applications. This review comprehensively elaborates on atomically substitutional engineering in TMD layers, including theoretical foundations, synthetic strategies, tailored properties, and superior applications. The emerging type of ternary TMDs, Janus TMDs, is presented specifically to highlight their typical compounds, fabrication methods, and potential applications. Finally, opportunities and challenges for further development of multinary TMDs are envisioned to expedite the evolution of this pivotal field.

Highlights:
1 Atomically substitutional engineering in binary transition metal dichalcogenides (TMDs) enables the facile production of ternary or quaternary TMDs with tunable (opto)electronic properties spanning the entire compositional spectrum.
2 A comprehensive overview is provided on multinary TMDs, including Janus-type structures, aiming to elaborate on their theoretical foundations, synthetic strategies, tailored properties, and superior applications.
3 The challenges and opportunities faced in accelerating the exploitation of multinary TMDs as highly promising nanomaterials are discussed.

Integrating Levels of Hierarchical Organization in Porous Organic Molecular Materials

Jesus Ferrando‑Soria, Antonio Fernandez — Fri, 12 Jan 2024 00:00:00 +0000

Porous organic molecular materials (POMMs) are an emergent class of molecular-based materials characterized by the formation of extended porous frameworks, mainly held by non-covalent interactions. POMMs represent a variety of chemical families, such as hydrogen-bonded organic frameworks, porous organic salts, porous organic cages, C − H⋅⋅⋅π microporous crystals, supramolecular organic frameworks, π-organic frameworks, halogen-bonded organic framework, and intrinsically porous molecular materials. In some porous materials such as zeolites and metal organic frameworks, the integration of multiscale has been adopted to build materials with multifunctionality and optimized properties. Therefore, considering the significant role of hierarchy in porous materials and the growing importance of POMMs in the realm of synthetic porous materials, we consider it appropriate to dedicate for the first time a critical review covering both topics. Herein, we will provide a summary of literature examples showcasing hierarchical POMMs, with a focus on their main synthetic approaches, applications, and the advantages brought forth by introducing hierarchy.

Highlights:
1 This review covers the extent of the integration of hierarchy in porous organic molecular materials (POMMs) for the first time.
2 Three main hierarchies are identified in POMMs: composition, architecture, and porosity.
3 The synthesis and applications of hierarchical POMMs, while highlighting the advantages of having hierarchy, are discussed.

Chalcogenide Ovonic Threshold Switching Selector

Thu, 11 Jan 2024 00:00:00 +0000

Today’s explosion of data urgently requires memory technologies capable of storing large volumes of data in shorter time frames, a feat unattainable with Flash or DRAM. Intel Optane, commonly referred to as three-dimensional phase change memory, stands out as one of the most promising candidates. The Optane with cross-point architecture is constructed through layering a storage element and a selector known as the ovonic threshold switch (OTS). The OTS device, which employs chalcogenide film, has thereby gathered increased attention in recent years. In this paper, we begin by providing a brief introduction to the discovery process of the OTS phenomenon. Subsequently, we summarize the key electrical parameters of OTS devices and delve into recent explorations of OTS materials, which are categorized as Se-based, Te-based, and S-based material systems. Furthermore, we discuss various models for the OTS switching mechanism, including field-induced nucleation model, as well as several carrier injection models. Additionally, we review the progress and innovations in OTS mechanism research. Finally, we highlight the successful application of OTS devices in three-dimensional high-density memory and offer insights into their promising performance and extensive prospects in emerging applications, such as self-selecting memory and neuromorphic computing.

Highlights:
1 The development history and key milestones of ovonic threshold switch (OTS) materials were comprehensively summarized. Combined with the latest advancements of OTS research, the mainstream OTS material systems were systematically introduced.
2 A thorough overview of the prevailing viewpoints regarding the OTS switching mechanisms was presented.
3 Recent progress in OTS devices for applications in 3D memory, self-selecting memory, and neuromorphic computing was summarized.

Design Strategies for Aqueous Zinc Metal Batteries with High Zinc Utilization: From Metal Anodes to Anode-Free Structures

Xianfu Zhang, Long Zhang, Xinyuan Jia, Wen Song, Yongchang Liu — Thu, 04 Jan 2024 00:00:00 +0000

Aqueous zinc metal batteries (AZMBs) are promising candidates for next-generation energy storage due to the excellent safety, environmental friendliness, natural abundance, high theoretical specific capacity, and low redox potential of zinc (Zn) metal. However, several issues such as dendrite formation, hydrogen evolution, corrosion, and passivation of Zn metal anodes cause irreversible loss of the active materials. To solve these issues, researchers often use large amounts of excess Zn to ensure a continuous supply of active materials for Zn anodes. This leads to the ultralow utilization of Zn anodes and squanders the high energy density of AZMBs. Herein, the design strategies for AZMBs with high Zn utilization are discussed in depth, from utilizing thinner Zn foils to constructing anode-free structures with theoretical Zn utilization of 100%, which provides comprehensive guidelines for further research. Representative methods for calculating the depth of discharge of Zn anodes with different structures are first summarized. The reasonable modification strategies of Zn foil anodes, current collectors with pre-deposited Zn, and anode-free aqueous Zn metal batteries (AF-AZMBs) to improve Zn utilization are then detailed. In particular, the working mechanism of AF-AZMBs is systematically introduced. Finally, the challenges and perspectives for constructing high-utilization Zn anodes are presented.

Highlights:
1 Representative methods for calculating the depth of discharge of different Zn anodes are introduced.
2 Recent advances of aqueous Zn metal batteries with high Zn utilization are reviewed and categorized according to Zn anodes with different structures.
3 The working mechanism of anode-free aqueous Zn metal batteries is introduced in detail, and different modification strategies for anode-free aqueous Zn metal batteries are summarized.

A Review on Engineering Design for Enhancing Interfacial Contact in Solid-State Lithium–Sulfur Batteries

Bingxin Qi, Xinyue Hong, Ying Jiang, Jing Shi, Mingrui Zhang, Wen Yan, Chao Lai — Thu, 04 Jan 2024 00:00:00 +0000

The utilization of solid-state electrolytes (SSEs) presents a promising solution to the issues of safety concern and shuttle effect in Li–S batteries, which has garnered significant interest recently. However, the high interfacial impedances existing between the SSEs and the electrodes (both lithium anodes and sulfur cathodes) hinder the charge transfer and intensify the uneven deposition of lithium, which ultimately result in insufficient capacity utilization and poor cycling stability. Hence, the reduction of interfacial resistance between SSEs and electrodes is of paramount importance in the pursuit of efficacious solid-state batteries. In this review, we focus on the experimental strategies employed to enhance the interfacial contact between SSEs and electrodes, and summarize recent progresses of their applications in solid-state Li–S batteries. Moreover, the challenges and perspectives of rational interfacial design in practical solid-state Li–S batteries are outlined as well. We expect that this review will provide new insights into the further technique development and practical applications of solid-state lithium batteries.

Highlights:
1 The engineering design principles for enhancing interfacial contact between the electrodes (Li anodes and S cathode) and solid-state electrolytes in solid-state Li–S batteries are classified and discussed.
2 Research progresses of experimental strategies for reducing interfacial impedance in solid-state Li–S batteries are summarized.
3 Challenges and future perspectives of rational interfacial strategies in solid-state Li–S batteries are highlighted.

Decade Milestone Advancement of Defect-Engineered g-C3N4 for Solar Catalytic Applications

Thu, 04 Jan 2024 00:00:00 +0000

Over the past decade, graphitic carbon nitride (g-C₃N₄) has emerged as a universal photocatalyst toward various sustainable carbo-neutral technologies. Despite solar applications discrepancy, g-C₃N₄ is still confronted with a general fatal issue of insufficient supply of thermodynamically active photocarriers due to its inferior solar harvesting ability and sluggish charge transfer dynamics. Fortunately, this could be significantly alleviated by the “all-in-one” defect engineering strategy, which enables a simultaneous amelioration of both textural uniqueness and intrinsic electronic band structures. To this end, we have summarized an unprecedently comprehensive discussion on defect controls including the vacancy/non-metallic dopant creation with optimized electronic band structure and electronic density, metallic doping with ultra-active coordinated environment (M–N_x, M–C₂N₂, M–O bonding), functional group grafting with optimized band structure, and promoted crystallinity with extended conjugation π system with weakened interlayered van der Waals interaction. Among them, the defect states induced by various defect types such as N vacancy, P/S/halogen dopants, and cyano group in boosting solar harvesting and accelerating photocarrier transfer have also been emphasized. More importantly, the shallow defect traps identified by femtosecond transient absorption spectra (fs-TAS) have also been highlighted. It is believed that this review would pave the way for future readers with a unique insight into a more precise defective g-C₃N₄ “customization”, motivating more profound thinking and flourishing research outputs on g-C₃N₄-based photocatalysis.

Highlights:
1 This review summarizes the decade milestone advancement of defect-engineered g-C₃N₄ and emphasizes the roles of crystallinity and defect traps toward a more precise defective g-C₃N₄ “customization” in the future.
2 A critical insight into the defect traps has been discussed in depth, probing the defect-induced states and photocarrier transfer kinetics of g-C₃N₄.
3 The prospect and outlooking for precise defective g-C₃N₄ “customization” is proposed.

Superhydrophobic Surface-Assisted Preparation of Microspheres and Supraparticles and Their Applications

Thu, 04 Jan 2024 00:00:00 +0000

Superhydrophobic surface (SHS) has been well developed, as SHS renders the property of minimizing the water/solid contact interface. Water droplets deposited onto SHS with contact angles exceeding 150°, allow them to retain spherical shapes, and the low adhesion of SHS facilitates easy droplet collection when tilting the substrate. These characteristics make SHS suitable for a wide range of applications. One particularly promising application is the fabrication of microsphere and supraparticle materials. SHS offers a distinct advantage as a universal platform capable of providing customized services for a variety of microspheres and supraparticles. In this review, an overview of the strategies for fabricating microspheres and supraparticles with the aid of SHS, including cross-linking process, polymer melting, and droplet template evaporation methods, is first presented. Then, the applications of microspheres and supraparticles formed onto SHS are discussed in detail, for example, fabricating photonic devices with controllable structures and tunable structural colors, acting as catalysts with emerging or synergetic properties, being integrated into the biomedical field to construct the devices with different medicinal purposes, being utilized for inducing protein crystallization and detecting trace amounts of analytes. Finally, the perspective on future developments involved with this research field is given, along with some obstacles and opportunities.

Highlights:
1 An overview of the superhydrophobic surface -assisted strategies for fabricating microspheres and supraparticles are presented.
2 The applications of microspheres and supraparticles fabricated using SHS-assisted strategies are discussed in detail.
3 NCrucial challenges facing the development of microspheres and supraparticles fabricated through SHS-assisted strategies are analysed.

Cu-Based Materials for Enhanced C2+ Product Selectivity in Photo-/Electro-Catalytic CO2 Reduction: Challenges and Prospects

Baker Rhimi, Min Zhou, Zaoxue Yan, Xiaoyan Cai, Zhifeng Jiang — Thu, 04 Jan 2024 00:00:00 +0000

Carbon dioxide conversion into valuable products using photocatalysis and electrocatalysis is an effective approach to mitigate global environmental issues and the energy shortages. Among the materials utilized for catalytic reduction of CO₂, Cu-based materials are highly advantageous owing to their widespread availability, cost-effectiveness, and environmental sustainability. Furthermore, Cu-based materials demonstrate interesting abilities in the adsorption and activation of carbon dioxide, allowing the formation of C₂₊ compounds through C–C coupling process. Herein, the basic principles of photocatalytic CO₂ reduction reactions (PCO₂RR) and electrocatalytic CO₂ reduction reaction (ECO₂RR) and the pathways for the generation C₂₊ products are introduced. This review categorizes Cu-based materials into different groups including Cu metal, Cu oxides, Cu alloys, and Cu SACs, Cu heterojunctions based on their catalytic applications. The relationship between the Cu surfaces and their efficiency in both PCO₂RR and ECO₂RR is emphasized. Through a review of recent studies on PCO₂RR and ECO₂RR using Cu-based catalysts, the focus is on understanding the underlying reasons for the enhanced selectivity toward C₂₊ products. Finally, the opportunities and challenges associated with Cu-based materials in the CO₂ catalytic reduction applications are presented, along with research directions that can guide for the design of highly active and selective Cu-based materials for CO₂ reduction processes in the future.

Highlights:
1 The latest advancements in Cu-based catalysts for photocatalytic and electrocatalytic CO₂ reduction into C²⁺ products are reported.
2 The relationship between the Cu surfaces and their efficiency in photocatalytic and electrocatalytic CO₂ reduction is emphasized.
3 The opportunities and challenges associated with Cu-based materials in the CO₂ catalytic reduction applications are presented.

Advances in Wireless, Batteryless, Implantable Electronics for Real-Time, Continuous Physiological Monitoring

Hyeonseok Kim, Bruno Rigo, Gabriella Wong, Yoon Jae Lee, Woon‑Hong Yeo — Fri, 15 Dec 2023 00:00:00 +0000

This review summarizes recent progress in developing wireless, batteryless, fully implantable biomedical devices for real-time continuous physiological signal monitoring, focusing on advancing human health care. Design considerations, such as biological constraints, energy sourcing, and wireless communication, are discussed in achieving the desired performance of the devices and enhanced interface with human tissues. In addition, we review the recent achievements in materials used for developing implantable systems, emphasizing their importance in achieving multi-functionalities, biocompatibility, and hemocompatibility. The wireless, batteryless devices offer minimally invasive device insertion to the body, enabling portable health monitoring and advanced disease diagnosis. Lastly, we summarize the most recent practical applications of advanced implantable devices for human health care, highlighting their potential for immediate commercialization and clinical uses.

Highlights:
1 This article summarizes the recent advances in wireless, batteryless, implantable electronics for continuous physiological monitoring.
2 The critical factors that affect the design of implantable electronics for biosensing are discussed.
3 The recent progress of material research for developing various implantable devices is summarized.
4 This article reviews various biomedical applications of implantable devices for human healthcare.

Asymmetric Electrolytes Design for Aqueous Multivalent Metal Ion Batteries

Xiaochen Yang, Xinyu Wang, Yue Xiang, Longtao Ma, Wei Huang — Fri, 15 Dec 2023 00:00:00 +0000

With the rapid development of portable electronics and electric road vehicles, high-energy-density batteries have been becoming front-burner issues. Traditionally, homogeneous electrolyte cannot simultaneously meet diametrically opposed demands of high-potential cathode and low-potential anode, which are essential for high-voltage batteries. Meanwhile, homogeneous electrolyte is difficult to achieve bi- or multi-functions to meet different requirements of electrodes. In comparison, the asymmetric electrolyte with bi- or multi-layer disparate components can satisfy distinct requirements by playing different roles of each electrolyte layer and meanwhile compensates weakness of individual electrolyte. Consequently, the asymmetric electrolyte can not only suppress by-product sedimentation and continuous electrolyte decomposition at the anode while preserving active substances at the cathode for high-voltage batteries with long cyclic lifespan. In this review, we comprehensively divide asymmetric electrolytes into three categories: decoupled liquid-state electrolytes, bi-phase solid/liquid electrolytes and decoupled asymmetric solid-state electrolytes. The design principles, reaction mechanism and mutual compatibility are also studied, respectively. Finally, we provide a comprehensive vision for the simplification of structure to reduce costs and increase device energy density, and the optimization of solvation structure at anolyte/catholyte interface to realize fast ion transport kinetics.

Highlights:
1 The working principle of the asymmetric electrolyte and the long-term-seated contradictory issues were analyzed.
2 The characterization methods for the interfaces of anolyte/catholyte and electrolyte/electrode were summarized for revealing the fundamental mechanism of asymmetric electrolytes.
3 The future research directions for asymmetric electrolyte systems were proposed.

Implantable Electrochemical Microsensors for In Vivo Monitoring of Animal Physiological Information

Tue, 12 Dec 2023 00:00:00 +0000

In vivo monitoring of animal physiological information plays a crucial role in promptly alerting humans to potential diseases in animals and aiding in the exploration of mechanisms underlying human diseases. Currently, implantable electrochemical microsensors have emerged as a prominent area of research. These microsensors not only fulfill the technical requirements for monitoring animal physiological information but also offer an ideal platform for integration. They have been extensively studied for their ability to monitor animal physiological information in a minimally invasive manner, characterized by their bloodless, painless features, and exceptional performance. The development of implantable electrochemical microsensors for in vivo monitoring of animal physiological information has witnessed significant scientific and technological advancements through dedicated efforts. This review commenced with a comprehensive discussion of the construction of microsensors, including the materials utilized and the methods employed for fabrication. Following this, we proceeded to explore the various implantation technologies employed for electrochemical microsensors. In addition, a comprehensive overview was provided of the various applications of implantable electrochemical microsensors, specifically in the monitoring of diseases and the investigation of disease mechanisms. Lastly, a concise conclusion was conducted on the recent advancements and significant obstacles pertaining to the practical implementation of implantable electrochemical microsensors.

Highlights:
1 The materials, fabrication methods, implantation technologies, and applications of implantable electrochemical microsensors for animals were summarized.
2 The implantable electrochemical microsensors for monitoring diseases and exploring disease mechanisms were discussed.
3 The current status, ongoing challenges, and future development prospects of implantable electrochemical microsensors in monitoring animal physiological information were highlighted.

Recent Advances in Patterning Strategies for Full-Color Perovskite Light-Emitting Diodes

Gwang Heon Lee, Kiwook Kim, Yunho Kim, Jiwoong Yang, Moon Kee Choi — Thu, 07 Dec 2023 00:00:00 +0000

Metal halide perovskites have emerged as promising light-emitting materials for next-generation displays owing to their remarkable material characteristics including broad color tunability, pure color emission with remarkably narrow bandwidths, high quantum yield, and solution processability. Despite recent advances have pushed the luminance efficiency of monochromic perovskite light-emitting diodes (PeLEDs) to their theoretical limits, their current fabrication using the spin-coating process poses limitations for fabrication of full-color displays. To integrate PeLEDs into full-color display panels, it is crucial to pattern red–green–blue (RGB) perovskite pixels, while mitigating issues such as cross-contamination and reductions in luminous efficiency. Herein, we present state-of-the-art patterning technologies for the development of full-color PeLEDs. First, we highlight recent advances in the development of efficient PeLEDs. Second, we discuss various patterning techniques of MPHs (i.e., photolithography, inkjet printing, electron beam lithography and laser-assisted lithography, electrohydrodynamic jet printing, thermal evaporation, and transfer printing) for fabrication of RGB pixelated displays. These patterning techniques can be classified into two distinct approaches: in situ crystallization patterning using perovskite precursors and patterning of colloidal perovskite nanocrystals. This review highlights advancements and limitations in patterning techniques for PeLEDs, paving the way for integrating PeLEDs into full-color panels.

Highlights:
1 This article reviews the recent progress in the patterning techniques of metal halide perovskites for full-color displays.
2 Patterning techniques of perovskites are subdivided into in situ crystallization and patterning of colloidal perovskite nanocrystals, including photolithography, inkjet printing, thermal evaporation, laser ablation, transfer printing, and so on.
3 The strength and weakness of each patterning methods are discussed in detail from the viewpoint of their applications in full-color displays.

Biological Interaction and Imaging of Ultrasmall Gold Nanoparticles

Dongmiao Sang, Xiaoxi Luo, Jinbin Liu — Mon, 04 Dec 2023 00:00:00 +0000

Ultrasmall gold nanoparticles (AuNPs) typically includes atomically precise gold nanoclusters (AuNCs) and AuNPs with a core size below 3 nm. Serving as a bridge between small molecules and traditional inorganic nanoparticles, the ultrasmall AuNPs show the unique advantages of both small molecules (e.g., rapid distribution, renal clearance, low non-specific organ accumulation) and nanoparticles (e.g., long blood circulation and enhanced permeability and retention effect). The emergence of ultrasmall AuNPs creates significant opportunities to address many challenges in the health field including disease diagnosis, monitoring and treatment. Since the nano–bio interaction dictates the overall biological applications of the ultrasmall AuNPs, this review elucidates the recent advances in the biological interactions and imaging of ultrasmall AuNPs. We begin with the introduction of the factors that influence the cellular interactions of ultrasmall AuNPs. We then discuss the organ interactions, especially focus on the interactions of the liver and kidneys. We further present the recent advances in the tumor interactions of ultrasmall AuNPs. In addition, the imaging performance of the ultrasmall AuNPs is summarized and discussed. Finally, we summarize this review and provide some perspective on the future research direction of the ultrasmall AuNPs, aiming to accelerate their clinical translation.

Highlights:
1 The ultrasmall gold nanoparticles (AuNPs), serving as a bridge between small molecules and traditional inorganic nanoparticles, create significant opportunities to address many challenges in the health field.
2 This review discusses the recent advances in the biological interactions and imaging of ultrasmall AuNPs.
3 The challenges and the future development directions of the ultrasmall AuNPs are presented.

Recent Developments in Metallic Degradable Micromotors for Biomedical and Environmental Remediation Applications

Thu, 30 Nov 2023 00:00:00 +0000

Synthetic micromotor has gained substantial attention in biomedicine and environmental remediation. Metal-based degradable micromotor composed of magnesium (Mg), zinc (Zn), and iron (Fe) have promise due to their nontoxic fuel-free propulsion, favorable biocompatibility, and safe excretion of degradation products Recent advances in degradable metallic micromotor have shown their fast movement in complex biological media, efficient cargo delivery and favorable biocompatibility. A noteworthy number of degradable metal-based micromotors employ bubble propulsion, utilizing water as fuel to generate hydrogen bubbles. This novel feature has projected degradable metallic micromotors for active in vivo drug delivery applications. In addition, understanding the degradation mechanism of these micromotors is also a key parameter for their design and performance. Its propulsion efficiency and life span govern the overall performance of a degradable metallic micromotor. Here we review the design and recent advancements of metallic degradable micromotors. Furthermore, we describe the controlled degradation, efficient in vivo drug delivery, and built-in acid neutralization capabilities of degradable micromotors with versatile biomedical applications. Moreover, we discuss micromotors’ efficacy in detecting and destroying environmental pollutants. Finally, we address the limitations and future research directions of degradable metallic micromotors.

Highlights:
1 This review discusses the potential of degradable metallic micromotors for a variety of biomedical and environmental applications.
2 The design principles, fabrication techniques and degradation mechanisms of degradable metallic micromotors are reviewed in detail.
3 Challenges and future directions for the development of degradable metallic micromotors for real-life applications are presented.

Untethered Micro/Nanorobots for Remote Sensing: Toward Intelligent Platform

Qianqian Wang, Shihao Yang, Li Zhang — Thu, 30 Nov 2023 00:00:00 +0000

Untethered micro/nanorobots that can wirelessly control their motion and deformation state have gained enormous interest in remote sensing applications due to their unique motion characteristics in various media and diverse functionalities. Researchers are developing micro/nanorobots as innovative tools to improve sensing performance and miniaturize sensing systems, enabling in situ detection of substances that traditional sensing methods struggle to achieve. Over the past decade of development, significant research progress has been made in designing sensing strategies based on micro/nanorobots, employing various coordinated control and sensing approaches. This review summarizes the latest developments on micro/nanorobots for remote sensing applications by utilizing the self-generated signals of the robots, robot behavior, microrobotic manipulation, and robot-environment interactions. Providing recent studies and relevant applications in remote sensing, we also discuss the challenges and future perspectives facing micro/nanorobots-based intelligent sensing platforms to achieve sensing in complex environments, translating lab research achievements into widespread real applications.

Highlights:
1 A systematic review of latest developments of untethered micro/nanorobots-based remote sensing systems with an emphasis on designing new coordinated control and sensing approaches.
2 The propulsion/motion control, functionalization of micro/nanorobots, sensing mechanisms, and applications are reviewed based on the up-to-date works.
3 The design and application of micro/nanorobot-based sensing platforms are discussed with the goal of building intelligent remote sensing systems.

Advances of Electrochemical and Electrochemiluminescent Sensors Based on Covalent Organic Frameworks

Yue Cao, Ru Wu, Yan‑Yan Gao, Yang Zhou, Jun‑Jie Zhu — Thu, 30 Nov 2023 00:00:00 +0000

Covalent organic frameworks (COFs), a rapidly developing category of crystalline conjugated organic polymers, possess highly ordered structures, large specific surface areas, stable chemical properties, and tunable pore microenvironments. Since the first report of boroxine/boronate ester-linked COFs in 2005, COFs have rapidly gained popularity, showing important application prospects in various fields, such as sensing, catalysis, separation, and energy storage. Among them, COFs-based electrochemical (EC) sensors with upgraded analytical performance are arousing extensive interest. In this review, therefore, we summarize the basic properties and the general synthesis methods of COFs used in the field of electroanalytical chemistry, with special emphasis on their usages in the fabrication of chemical sensors, ions sensors, immunosensors, and aptasensors. Notably, the emerged COFs in the electrochemiluminescence (ECL) realm are thoroughly covered along with their preliminary applications. Additionally, final conclusions on state-of-the-art COFs are provided in terms of EC and ECL sensors, as well as challenges and prospects for extending and improving the research and applications of COFs in electroanalytical chemistry.

Highlights:
1 Covalent organic frameworks (COFs) show enormous potential for building high-performance electrochemical sensors due to their high porosity, large specific surface areas, stable rigid topology, ordered structures, and tunable pore microenvironments.
2 The basic properties, monomers, and general synthesis methods of COFs in the electroanalytical chemistry field are introduced, with special emphasis on their usages in the fabrication of chemical sensors, ions sensors, immunosensors, and aptasensors.
3 The emerged COFs in the electrochemiluminescence realm are thoroughly covered along with their preliminary applications.

Electrolyte Design for Low-Temperature Li-Metal Batteries: Challenges and Prospects

Siyu Sun, Kehan Wang, Zhanglian Hong, Mingjia Zhi, Kai Zhang, Jijian Xu — Wed, 29 Nov 2023 00:00:00 +0000

Electrolyte design holds the greatest opportunity for the development of batteries that are capable of sub-zero temperature operation. To get the most energy storage out of the battery at low temperatures, improvements in electrolyte chemistry need to be coupled with optimized electrode materials and tailored electrolyte/electrode interphases. Herein, this review critically outlines electrolytes’ limiting factors, including reduced ionic conductivity, large de-solvation energy, sluggish charge transfer, and slow Li-ion transportation across the electrolyte/electrode interphases, which affect the low-temperature performance of Li-metal batteries. Detailed theoretical derivations that explain the explicit influence of temperature on battery performance are presented to deepen understanding. Emerging improvement strategies from the aspects of electrolyte design and electrolyte/electrode interphase engineering are summarized and rigorously compared. Perspectives on future research are proposed to guide the ongoing exploration for better low-temperature Li-metal batteries.

Highlights:
1 A critical assessment of electrolytes’ limiting factors, which affect the low-temperature performance of Li-metal batteries.
2 Summary of emerging strategies to improve low-temperature performance from the aspects of electrolyte design and electrolyte/electrode interphase engineering.
3 Perspectives and challenges on how to develop creative solutions in electrolytes and correlative materials for low-temperature operation.

Nanoparticle Exsolution on Perovskite Oxides: Insights into Mechanism, Characteristics and Novel Strategies

Tue, 28 Nov 2023 00:00:00 +0000

Supported nanoparticles have attracted considerable attention as a promising catalyst for achieving unique properties in numerous applications, including fuel cells, chemical conversion, and batteries. Nanocatalysts demonstrate high activity by expanding the number of active sites, but they also intensify deactivation issues, such as agglomeration and poisoning, simultaneously. Exsolution for bottom-up synthesis of supported nanoparticles has emerged as a breakthrough technique to overcome limitations associated with conventional nanomaterials. Nanoparticles are uniformly exsolved from perovskite oxide supports and socketed into the oxide support by a one-step reduction process. Their uniformity and stability, resulting from the socketed structure, play a crucial role in the development of novel nanocatalysts. Recently, tremendous research efforts have been dedicated to further controlling exsolution particles. To effectively address exsolution at a more precise level, understanding the underlying mechanism is essential. This review presents a comprehensive overview of the exsolution mechanism, with a focus on its driving force, processes, properties, and synergetic strategies, as well as new pathways for optimizing nanocatalysts in diverse applications.

Highlights:
1 Fundamental mechanisms in terms of driving force, material design, and exsolution processes are outlined, and novel behaviors of socketing and shape-shifting throughout the interaction with the oxide support are discussed.
2 This review examines the key control factors, encompassing external conditions and intrinsic properties that affect the surface exsolution of metallic nanoparticles.
3 The extraordinary nature of exsolution particles and their effect on various applications are discussed, along with the latest strategies for improving exsolution behavior.

Deformable Catalytic Material Derived from Mechanical Flexibility for Hydrogen Evolution Reaction

Fri, 24 Nov 2023 00:00:00 +0000

Deformable catalytic material with excellent flexible structure is a new type of catalyst that has been applied in various chemical reactions, especially electrocatalytic hydrogen evolution reaction (HER). In recent years, deformable catalysts for HER have made great progress and would become a research hotspot. The catalytic activities of deformable catalysts could be adjustable by the strain engineering and surface reconfiguration. The surface curvature of flexible catalytic materials is closely related to the electrocatalytic HER properties. Here, firstly, we systematically summarized self-adaptive catalytic performance of deformable catalysts and various micro–nanostructures evolution in catalytic HER process. Secondly, a series of strategies to design highly active catalysts based on the mechanical flexibility of low-dimensional nanomaterials were summarized. Last but not least, we presented the challenges and prospects of the study of flexible and deformable micro–nanostructures of electrocatalysts, which would further deepen the understanding of catalytic mechanisms of deformable HER catalyst.

Highlights:
1 The main effects of deformation of flexible catalytic materials on the catalytic hydrogen evolution reaction performance are discussed, and a series of novel strategies to design highly active catalysts based on the mechanical flexibility of low-dimensional nanomaterials are summarized in detail.
2 This review provides a strategic choice for the rational design of low-cost and high-performance industrialized electrocatalysts.

From VIB- to VB-Group Transition Metal Disulfides: Structure Engineering Modulation for Superior Electromagnetic Wave Absorption

Thu, 23 Nov 2023 00:00:00 +0000

The laminated transition metal disulfides (TMDs), which are well known as typical two-dimensional (2D) semiconductive materials, possess a unique layered structure, leading to their wide-spread applications in various fields, such as catalysis, energy storage, sensing, etc. In recent years, a lot of research work on TMDs based functional materials in the fields of electromagnetic wave absorption (EMA) has been carried out. Therefore, it is of great significance to elaborate the influence of TMDs on EMA in time to speed up the application. In this review, recent advances in the development of electromagnetic wave (EMW) absorbers based on TMDs, ranging from the VIB group to the VB group are summarized. Their compositions, microstructures, electronic properties, and synthesis methods are presented in detail. Particularly, the modulation of structure engineering from the aspects of heterostructures, defects, morphologies and phases are systematically summarized, focusing on optimizing impedance matching and increasing dielectric and magnetic losses in the EMA materials with tunable EMW absorption performance. Milestones as well as the challenges are also identified to guide the design of new TMDs based dielectric EMA materials with high performance.

Highlights:
1 A systematic summary of current research trends in the development of transition metal disulfides (TMDs) electromagnetic wave (EMW) absorption materials.
2 In-depth comparisons on the structures, preparation methods, application merits of VIB- and VB-group TMDs.
3 Structure engineering modulation of TMDs in achieving superior EMW absorption is outlined from the viewpoints of heterostructures, defects, morphologies, and phases.
4 Exclusive insights into the challenges, strategies, and opportunities in the design of EMW absorption materials with outstanding performance are provided.

Deep Insight of Design, Mechanism, and Cancer Theranostic Strategy of Nanozymes

Tue, 21 Nov 2023 00:00:00 +0000

Since the discovery of enzyme-like activity of Fe₃O₄ nanoparticles in 2007, nanozymes are becoming the promising substitutes for natural enzymes due to their advantages of high catalytic activity, low cost, mild reaction conditions, good stability, and suitable for large-scale production. Recently, with the cross fusion of nanomedicine and nanocatalysis, nanozyme-based theranostic strategies attract great attention, since the enzymatic reactions can be triggered in the tumor microenvironment to achieve good curative effect with substrate specificity and low side effects. Thus, various nanozymes have been developed and used for tumor therapy. In this review, more than 270 research articles are discussed systematically to present progress in the past five years. First, the discovery and development of nanozymes are summarized. Second, classification and catalytic mechanism of nanozymes are discussed. Third, activity prediction and rational design of nanozymes are focused by highlighting the methods of density functional theory, machine learning, biomimetic and chemical design. Then, synergistic theranostic strategy of nanozymes are introduced. Finally, current challenges and future prospects of nanozymes used for tumor theranostic are outlined, including selectivity, biosafety, repeatability and stability, in-depth catalytic mechanism, predicting and evaluating activities.

Highlights:
1 Classification and catalytic mechanism of nanozymes with different mimicking activities are dissertated.
2 Activity prediction and rational design methods of nanozymes are highlighted, including density functional theory, machine learning, biomimetic and chemical design.
3 The roles of nanozymes in different synergistic theranostic strategies for tumor are summarized and explained by representative examples in the past five years.

From Liquid to Solid-State Lithium Metal Batteries: Fundamental Issues and Recent Developments

Zhao Zhang, Wei‑Qiang Han — Mon, 20 Nov 2023 00:00:00 +0000

The widespread adoption of lithium-ion batteries has been driven by the proliferation of portable electronic devices and electric vehicles, which have increasingly stringent energy density requirements. Lithium metal batteries (LMBs), with their ultralow reduction potential and high theoretical capacity, are widely regarded as the most promising technical pathway for achieving high energy density batteries. In this review, we provide a comprehensive overview of fundamental issues related to high reactivity and migrated interfaces in LMBs. Furthermore, we propose improved strategies involving interface engineering, 3D current collector design, electrolyte optimization, separator modification, application of alloyed anodes, and external field regulation to address these challenges. The utilization of solid-state electrolytes can significantly enhance the safety of LMBs and represents the only viable approach for advancing them. This review also encompasses the variation in fundamental issues and design strategies for the transition from liquid to solid electrolytes. Particularly noteworthy is that the introduction of SSEs will exacerbate differences in electrochemical and mechanical properties at the interface, leading to increased interface inhomogeneity—a critical factor contributing to failure in all-solid-state lithium metal batteries. Based on recent research works, this perspective highlights the current status of research on developing high-performance LMBs.

Highlights:
1 The pursuit of high specific energy and high safety has promoted the transformation of lithium metal batteries from liquid to solid-state systems.
2 In addition to high reactivity and mobile interface, all-solid-state lithium metal batteries (ASSLMBs) still faces severe inhomogeneity in mechanical and electrochemical properties.
3 The inherent trade-off in ASSLMBs lies between ionic conductivity and electrochemical window, mechanical strength and interface contact adequacy.

Exploring the Roles of Single Atom in Hydrogen Peroxide Photosynthesis

Kelin He, Zimo Huang, Chao Chen, Chuntian Qiu, Yu Lin Zhong, Qitao Zhang — Mon, 20 Nov 2023 00:00:00 +0000

This comprehensive review provides a deep exploration of the unique roles of single atom catalysts (SACs) in photocatalytic hydrogen peroxide (H₂O₂) production. SACs offer multiple benefits over traditional catalysts such as improved efficiency, selectivity, and flexibility due to their distinct electronic structure and unique properties. The review discusses the critical elements in the design of SACs, including the choice of metal atom, host material, and coordination environment, and how these elements impact the catalytic activity. The role of single atoms in photocatalytic H₂O₂ production is also analysed, focusing on enhancing light absorption and charge generation, improving the migration and separation of charge carriers, and lowering the energy barrier of adsorption and activation of reactants. Despite these advantages, several challenges, including H₂O₂ decomposition, stability of SACs, unclear mechanism, and low selectivity, need to be overcome. Looking towards the future, the review suggests promising research directions such as direct utilization of H₂O₂, high-throughput synthesis and screening, the creation of dual active sites, and employing density functional theory for investigating the mechanisms of SACs in H₂O₂ photosynthesis. This review provides valuable insights into the potential of single atom catalysts for advancing the field of photocatalytic H₂O₂ production.

Highlights:
1 The review explores single atom catalysts (SACs) for photocatalytic H2O2 production, highlighting their unique structure, properties, and advantages over traditional catalysts. It emphasizes the importance of metal atom types, host material selection, and coordination environment in SACs design.
2 The article explains how SACs enhance photocatalytic H₂O₂ production by improving light absorption, charge generation, migration, and lowering energy barriers for reactant adsorption and activation.
3 The review acknowledges challenges and future research directions in SACs for H₂O₂ photosynthesis.

An Electrochemical Perspective of Aqueous Zinc Metal Anode

Huibo Yan, Songmei Li, Jinyan Zhong, Bin Li — Fri, 17 Nov 2023 00:00:00 +0000

Based on the attributes of nonflammability, environmental benignity, and cost-effectiveness of aqueous electrolytes, as well as the favorable compatibility of zinc metal with them, aqueous zinc ions batteries (AZIBs) become the leading energy storage candidate to meet the requirements of safety and low cost. Yet, aqueous electrolytes, acting as a double-edged sword, also play a negative role by directly or indirectly causing various parasitic reactions at the zinc anode side. These reactions include hydrogen evolution reaction, passivation, and dendrites, resulting in poor Coulombic efficiency and short lifespan of AZIBs. A comprehensive review of aqueous electrolytes chemistry, zinc chemistry, mechanism and chemistry of parasitic reactions, and their relationship is lacking. Moreover, the understanding of strategies for suppressing parasitic reactions from an electrochemical perspective is not profound enough. In this review, firstly, the chemistry of electrolytes, zinc anodes, and parasitic reactions and their relationship in AZIBs are deeply disclosed. Subsequently, the strategies for suppressing parasitic reactions from the perspective of enhancing the inherent thermodynamic stability of electrolytes and anodes, and lowering the dynamics of parasitic reactions at Zn/electrolyte interfaces are reviewed. Lastly, the perspectives on the future development direction of aqueous electrolytes, zinc anodes, and Zn/electrolyte interfaces are presented.

Highlights:
1 Detailed discussion and summary of aqueous electrolyte chemistry, parasitic reactions chemistry, and storage energy chemistry and their relationship in aqueous zinc ions batteries are conducted.
2 The recent development of strategies for enhancing the inherent stability of electrolyte and zinc anode to restrain parasitic reactions is reviewed from a thermodynamic perspective.
3 The regulation strategies of electrolyte/electrode interfaces to block parasitic reactions by adsorbents and solid electrolyte interphase are reviewed from a kinetic perspective.

Artificial Intelligence Meets Flexible Sensors: Emerging Smart Flexible Sensing Systems Driven by Machine Learning and Artificial Synapses

Mon, 13 Nov 2023 00:00:00 +0000

The recent wave of the artificial intelligence (AI) revolution has aroused unprecedented interest in the intelligentialize of human society. As an essential component that bridges the physical world and digital signals, flexible sensors are evolving from a single sensing element to a smarter system, which is capable of highly efficient acquisition, analysis, and even perception of vast, multifaceted data. While challenging from a manual perspective, the development of intelligent flexible sensing has been remarkably facilitated owing to the rapid advances of brain-inspired AI innovations from both the algorithm (machine learning) and the framework (artificial synapses) level. This review presents the recent progress of the emerging AI-driven, intelligent flexible sensing systems. The basic concept of machine learning and artificial synapses are introduced. The new enabling features induced by the fusion of AI and flexible sensing are comprehensively reviewed, which significantly advances the applications such as flexible sensory systems, soft/humanoid robotics, and human activity monitoring. As two of the most profound innovations in the twenty-first century, the deep incorporation of flexible sensing and AI technology holds tremendous potential for creating a smarter world for human beings.

Highlights:
1 The latest progress of emerging smart flexible sensing systems driven by brain-inspired artificial intelligence (AI) from both the algorithm (machine learning) and the framework (artificial synapses) level is reviewed.
2 New enabling features such as powerful data analysis and intelligent decision-making resulting from the fusion of AI technology with flexible sensors are discussed.
3 Promising application prospects of AI-driven smart flexible sensing systems such as more intelligent monitoring for human activities, more humanoid feeling by artificial sensory organs, and more autonomous action of soft robotics are demonstrated.

Engineering Strategies for Suppressing the Shuttle Effect in Lithium–Sulfur Batteries

Fri, 10 Nov 2023 00:00:00 +0000

Lithium–sulfur (Li–S) batteries are supposed to be one of the most potential next-generation batteries owing to their high theoretical capacity and low cost. Nevertheless, the shuttle effect of firm multi-step two-electron reaction between sulfur and lithium in liquid electrolyte makes the capacity much smaller than the theoretical value. Many methods were proposed for inhibiting the shuttle effect of polysulfide, improving corresponding redox kinetics and enhancing the integral performance of Li–S batteries. Here, we will comprehensively and systematically summarize the strategies for inhibiting the shuttle effect from all components of Li–S batteries. First, the electrochemical principles/mechanism and origin of the shuttle effect are described in detail. Moreover, the efficient strategies, including boosting the sulfur conversion rate of sulfur, confining sulfur or lithium polysulfides (LPS) within cathode host, confining LPS in the shield layer, and preventing LPS from contacting the anode, will be discussed to suppress the shuttle effect. Then, recent advances in inhibition of shuttle effect in cathode, electrolyte, separator, and anode with the aforementioned strategies have been summarized to direct the further design of efficient materials for Li–S batteries. Finally, we present prospects for inhibition of the LPS shuttle and potential development directions in Li–S batteries.

Highlights:
1 The electrochemical principles/mechanism of Li–S batteries and origin of the shuttle effect have been discussed.
2 The efficient strategies have been summarized to inhibit the shuttle effect.
3 The recent advances of inhibition of shuttle effect in Li–S batteries for all components from anode to cathode.

A Review of Contact Electrification at Diversified Interfaces and Related Applications on Triboelectric Nanogenerator

Jun Hu, Mitsumasa Iwamoto, Xiangyu Chen — Mon, 13 Nov 2023 00:00:00 +0000

The triboelectric nanogenerator (TENG) can effectively collect energy based on contact electrification (CE) at diverse interfaces, including solid–solid, liquid–solid, liquid–liquid, gas–solid, and gas–liquid. This enables energy harvesting from sources such as water, wind, and sound. In this review, we provide an overview of the coexistence of electron and ion transfer in the CE process. We elucidate the diverse dominant mechanisms observed at different interfaces and emphasize the interconnectedness and complementary nature of interface studies. The review also offers a comprehensive summary of the factors influencing charge transfer and the advancements in interfacial modification techniques. Additionally, we highlight the wide range of applications stemming from the distinctive characteristics of charge transfer at various interfaces. Finally, this review elucidates the future opportunities and challenges that interface CE may encounter. We anticipate that this review can offer valuable insights for future research on interface CE and facilitate the continued development and industrialization of TENG.

Highlights:
1 The distinctive characteristics, underlying mechanisms, diverse range of selected materials, and modification methods of contact electrification (CE) at various interfaces are summarized and comparatively analyzed, offering valuable guidance for future investigations of triboelectric nanogenerator (TENG) at different interfaces.
2 This review gives a detailed insight into the unique applications of TENG relying on different interfacial electrification.
3 The challenges and development prospects of TENGs based on CE are discussed.

Trend of Developing Aqueous Liquid and Gel Electrolytes for Sustainable, Safe, and High-Performance Li-Ion Batteries

Donghwan Ji, Jaeyun Kim — Mon, 13 Nov 2023 00:00:00 +0000

Current lithium-ion batteries (LIBs) rely on organic liquid electrolytes that pose significant risks due to their flammability and toxicity. The potential for environmental pollution and explosions resulting from battery damage or fracture is a critical concern. Water-based (aqueous) electrolytes have been receiving attention as an alternative to organic electrolytes. However, a narrow electrochemical-stability window, water decomposition, and the consequent low battery operating voltage and energy density hinder the practical use of aqueous electrolytes. Therefore, developing novel aqueous electrolytes for sustainable, safe, high-performance LIBs remains challenging. This Review first commences by summarizing the roles and requirements of electrolytes–separators and then delineates the progression of aqueous electrolytes for LIBs, encompassing aqueous liquid and gel electrolyte development trends along with detailed principles of the electrolytes. These aqueous electrolytes are progressed based on strategies using superconcentrated salts, concentrated diluents, polymer additives, polymer networks, and artificial passivation layers, which are used for suppressing water decomposition and widening the electrochemical stability window of water of the electrolytes. In addition, this Review discusses potential strategies for the implementation of aqueous Li-metal batteries with improved electrolyte–electrode interfaces. A comprehensive understanding of each strategy in the aqueous system will assist in the design of an aqueous electrolyte and the development of sustainable and safe high-performance batteries.

Highlights:
1 This Review encompasses the role, requirement, and development direction of water-based electrolytes for sustainable, safe, high-performance Li-ion batteries.
2 Water-based electrolytes (aqueous liquid and gel electrolytes) and their mechanisms are comprehensively summarized to widen the electrolyte electrochemical stability window and battery operating voltage and to achieve long-term operation stability.