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Vol. 18 (2026)

Ultrafast Sulfur Redox Dynamics Enabled by a PPy@N-TiO2 Z-Scheme Heterojunction Photoelectrode for Photo-Assisted Lithium–Sulfur Batteries

https://doi.org/10.1007/s40820-025-01946-3
Fei Zhao
State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, People’s Republic of China
Yibo He
State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, People’s Republic of China
Xuhong Li
State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, People’s Republic of China
Ke Yang
State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, People’s Republic of China
Shuo Chen
State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, People’s Republic of China
Yuanzhi Jiang
Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Nankai University, Tianjin 300071, People’s Republic of China
Xue‑Sen Wang
Department of Physics, National University of Singapore, Singapore 117543, Singapore
Chunyuan Song
State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, People’s Republic of China
Xuqing Liu
State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, People’s Republic of China

Corresponding Author: Yibo He

heyibo@nwpu.edu.cn

Nano-Micro Letters, Vol. 18 (2026), Article Number: 92

Abstract

Photo-assisted lithium–sulfur batteries (PALSBs) offer an eco-friendly solution to address the issue of sluggish reaction kinetics of conventional LSBs. However, designing an efficient photoelectrode for practical implementation remains a significant challenge. Herein, we construct a free-standing polymer–inorganic hybrid photoelectrode with a direct Z-scheme heterostructure to develop high-efficiency PALSBs. Specifically, polypyrrole (PPy) is in situ vapor-phase polymerized on the surface of N-doped TiO2 nanorods supported on carbon cloth (N-TiO2/CC), thereby forming a well-defined p–n heterojunction. This architecture efficiently facilitates the carrier separation of photo-generated electron–hole pairs and significantly enhances carrier transport by creating a built-in electric field. Thus, the PPy@N-TiO2/CC can simultaneously act as a photocatalyst and an electrocatalyst to accelerate the reduction and evolution of sulfur, enabling ultrafast sulfur redox dynamics, as convincingly validated by both theoretical simulations and experimental results. Consequently, the PPy@N-TiO2/CC PALSB achieves a high discharge capacity of 1653 mAh g−1, reaching 98.7% of the theoretical value. Furthermore, 5 h of photo-charging without external voltage enables the PALSB to deliver a discharge capacity of 333 mAh g−1, achieving dual-mode energy harvesting capabilities. This work successfully integrates solar energy conversion and storage within a rechargeable battery system, providing a promising strategy for sustainable energy storage technologies.


Highlights:
1 A novel polymer–inorganic hybrid photoelectrode (PPy@N-TiO2/CC) with a Z-scheme heterostructure was first constructed for high-efficiency photo-assisted lithium–sulfur battery (PALSB).
2 PPy@N-TiO2/CC acts not only as a photocatalyst to accelerate sulfur redox reductions through photocatalytic, photoconductive, and photo-charge effects, but also as an electrocatalyst to facilitate intermediate polysulfide conversion.
3 PALSB achieves an ultrahigh discharge capacity of 1653 mAh g−1 and dual-mode energy harvesting: 5 h of photo-charging delivers a discharge capacity of 333 mAh g−1.

Keywords

Photo-assisted lithium–sulfur batteries Z-scheme heterojunction Electrocatalysis Photocatalysis Sulfur redox dynamics
Zhao, Fei, Yibo He, Xuhong Li, Ke Yang, Shuo Chen, Yuanzhi Jiang, Xue‑Sen Wang, Chunyuan Song, and Xuqing Liu. 2026. “Ultrafast Sulfur Redox Dynamics Enabled by a PPy@N-TiO2 Z-Scheme Heterojunction Photoelectrode for Photo-Assisted Lithium–Sulfur Batteries”. Nano-Micro Letters 18 (January):92. https://doi.org/10.1007/s40820-025-01946-3.
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