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Updated: May 26, 2026

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Cation-Limited Hydroxide Anion Diffusion Drives Asymmetric Hydrogen Kinetics on Transition-Metal Decorated Platinum
Chengzhang Wan1,2, Zisheng Zhang1,3, Zheng Weng2
1Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States.
Electrolyte cations significantly influence alkaline hydrogen evolution/oxidation reactions (HER/HOR). Transition-metal decoration on platinum surfaces breaks kinetic symmetry, revealing cation accumulation effects on HER/HOR performance.
Area of Science:
- Electrochemistry
- Materials Science
- Catalysis
Background:
- Electrocatalytic reactions involve dynamic, ion-regulated interfaces.
- Cations play a crucial role in alkaline hydrogen evolution/oxidation reactions (HER/HOR), contrary to the spectator assumption.
- Alkaline HER and HOR are generally considered reversible with symmetric kinetics on Pt catalysts.
Purpose of the Study:
- To investigate how transition-metal (TM) decoration on Pt surfaces affects the kinetic symmetry of HER and HOR.
- To elucidate the mechanism behind the observed kinetic differences, focusing on cation behavior and interfacial phenomena.
- To establish design principles for advanced alkaline electrocatalysts.
Main Methods:
- Experimental investigation using Ni-decorated Pt as a model system.
- Electrochemical analysis of HER and HOR kinetics under varying alkaline conditions.
- Systematic studies across different TM-decorated Pt surfaces correlated with TM oxidation potential.
Main Results:
- Ni-decorated Pt surfaces exhibit broken kinetic symmetry between HER and HOR.
- Ni-OH species enhance HER but suppress HOR kinetics via cation accumulation and suppressed hydroxide diffusion.
- A trend is observed based on TM oxidation potential, linking TM-OH formation to HER/HOR activity and limitations.
Conclusions:
- Cation accumulation at the interface, driven by TM-OH species, significantly impacts alkaline HER/HOR kinetics.
- The study establishes a mechanistic framework connecting cation behavior, hydroxide transport, and reaction rates.
- Findings provide crucial insights for designing efficient electrocatalysts for alkaline HER/HOR.
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