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Vol. 18 (2026)

Adjacent-Site Proximity as a Dominant Activity Descriptor in Single-Atom Pt Catalysts for Hydrogen Evolution Reaction

https://doi.org/10.1007/s40820-026-02201-z
Xue‑Lu Chen
State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, People’s Republic of China
Yu‑Yang Liu
Institute of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, People’s Republic of China
Sudip Biswas
State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, People’s Republic of China
Yi Yang
State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, People’s Republic of China
Yi Shi
School of Chemistry and Molecular Engineering, East China Normal University, Dongchuan Road 500, Shanghai 200241, People’s Republic of China
Chun‑Gen Liu
Institute of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, People’s Republic of China
Xing‑Hua Xia
State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, People’s Republic of China

Corresponding Author: Xing‑Hua Xia

xhxia@nju.edu.cn

Nano-Micro Letters, Vol. 18 (2026), Article Number: 350

Abstract

Precise control of adjacent-site proximity and electronic states in single-atom catalysts (SACs) enable atomic-level modulation of intrinsic catalytic properties. While the influence of electronic structure on catalytic performance is well established, the impact of adjacent-site proximity remains underexplored. Here, we report the single-atom platinum catalysts on MoS2 (Pt-SAC/MoS2), in which both the controlled enrichment of adjacent Pt (Ptadj) sites and the Pt oxidation state are tuned via galvanic displacement of underpotentially deposited Cu adatoms. We find that hydrogen evolution reaction (HER) activity is predominantly governed by non-bonded Pt∙∙∙Pt proximity rather than oxidation state: enriched Ptadj sites in PtSA-0.1/MoS2 exhibits a mass activity 41-fold higher than isolated Pt (Ptiso) sites in PtSA-0.3/MoS2 under acidic conditions. In situ infrared spectroscopy reveals that Ptiso sites preferentially bind linear adsorbed hydrogen intermediate (*HL), whereas Ptadj sites stabilize bridge hydrogen intermediate (*HB), which is indicative of adjacent-site proximity. Density functional theory calculations reveal that neighboring Pt atoms promote the formation of a three-center “Pt–H–Pt” bonding intermediate, which lowers the H–H coupling barrier and accelerates HER kinetics. These findings establish adjacent-site proximity as a dominant activity descriptor in SACs and provide new design principles for next-generation high-performance electrocatalysts.


Highlights:
1 Site-specific underpotential deposition strategy enables precise spatial control over atomic-level active sites, enriching adjacent Pt sites while tuning oxidation states
2 Adjacent-site proximity dominates hydrogen evolution reaction (HER) activity, with adjacent Pt sites deliver a 41-fold higher mass activity than isolated Pt sites.
3 Pt–H–Pt bridge intermediate at adjacent sites lowers the H–H coupling barrier and accelerates HER kinetics.

Keywords

Single-atom platinum Interatomic proximity H–adsorption mode Hydrogen evolution reaction Pt–H–Pt intermediate
Chen, Xue‑Lu, Yu‑Yang Liu, Sudip Biswas, Yi Yang, Yi Shi, Chun‑Gen Liu, and Xing‑Hua Xia. 2026. “Adjacent-Site Proximity As a Dominant Activity Descriptor in Single-Atom Pt Catalysts for Hydrogen Evolution Reaction”. Nano-Micro Letters 18 (May):350. https://doi.org/10.1007/s40820-026-02201-z.
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