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Journal article
Determining the Viability of Hydroxide-Mediated Bifunctional HER/HOR Mechanisms through Single-Crystal Voltammetry and Microkinetic Modeling
Journal of the Electrochemical Society, v 165(15), pp J3209-J3221
09 Oct 2018
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Abstract
The slow kinetics of the hydrogen oxidation and hydrogen evolution reactions (HER and HOR) in alkaline compared to acidic media remain a fundamental conundrum in modern electrocatalysis. Recent efforts have proposed that OH, as well as H, must bind optimally for improved kinetics, but the exact role of adsorbed OH is not yet known. In this work, we combine steady-state single-crystal voltammetry and microkinetic modeling to determine the roles of adsorbed hydroxide and the so-called bifunctional mechanism in alkaline HER and HOR kinetics. We consider both a direct Volmer mechanism, in which H and OH compete for sites on Pt (110), and an OH-mediated mechanism, in which Pt (111) adsorbs H while transition metal clusters adsorb OH. Our experimental and computational results show that on a thermodynamic coverage basis, increasing OH adsorption strength cannot promote faster HER/HOR kinetics. Only changes to the kinetic rate constants can explain experimental observations. We speculate that adequate electrocatalyst design in alkaline media additionally requires manipulation of interfacial water structure to lower energetic barriers for HER and HOR. (C) The Author(s) 2018. Published by ECS.
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Details
- Title
- Determining the Viability of Hydroxide-Mediated Bifunctional HER/HOR Mechanisms through Single-Crystal Voltammetry and Microkinetic Modeling
- Creators
- Luis Rebollar - Drexel UniversitySaad Intikhab - Drexel UniversityJoshua D. Snyder - Drexel UniversityMaureen H. Tang - Drexel University
- Publication Details
- Journal of the Electrochemical Society, v 165(15), pp J3209-J3221
- Publisher
- Electrochemical Soc Inc
- Number of pages
- 13
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemical and Biological Engineering
- Web of Science ID
- WOS:000446833200002
- Scopus ID
- 2-s2.0-85061460065
- Other Identifier
- 991019169627804721
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InCites Highlights
Data related to this publication, from InCites Benchmarking & Analytics tool:
- Web of Science research areas
- Electrochemistry
- Materials Science, Coatings & Films