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On the relationship between potential of zero charge and solvent dynamics in the reversible hydrogen electrode
Journal article   Peer reviewed

On the relationship between potential of zero charge and solvent dynamics in the reversible hydrogen electrode

Luis Rebollar, Saad Intikhab, Suihao Zhang, Huiqiu Deng, Zhenhua Zeng, Joshua D. Snyder and Maureen H. Tang
Journal of catalysis, v 398, pp 161-170
Jun 2021
DOI: https://doi.org/10.1016/j.jcat.2021.04.008
Featured in Collection :   UN Sustainable Development Goals @ Drexel

Abstract

Electric field Electrocatalysis Solvent effects
[Display omitted] •Caffeinating Pt(111) modifies interfacial water but not adsorbate binding energy.•Hydrogen kinetics correlate with potential of zero free charge better than total charge.•Solvent dynamics are unlikely to cause pzfc-kinetic correlation. The impact of interfacial electric fields on electrochemical reaction kinetics is assessed in the context of hydrogen electrocatalysis. Recent efforts have proposed that interfacial electric field strength, as described by the electrode’s potential of zero free charge (pzfc), contributes to the slow kinetics of the alkaline hydrogen evolution and oxidation reactions (HER/HOR) by hindering solvent reorganization. In this work, we examine through single-crystal voltammetry the importance of the interfacial electric field strength on hydrogen reaction kinetics using three complementary approaches: (1) correlating the pzfc with reaction kinetics using caffeinated Pt as a model surface; (2) varying the electrolyte ionic strength at constant pH; and (3) probing solvent dynamics via caffeinated kinetic isotope effects (KIEs). Our results show that pzfc seems to correlate with HER/HOR kinetics, but also suggest that the effect more likely originates from activation barriers to the reaction elementary steps than from electric field effects on solvent dynamics. Although the importance of interfacial phenomena such as the electrode’s pzfc and water reorganization energy are well established, the pzfc may not be a mechanistic descriptor of the alkaline hydrogen reaction kinetics. Surface additives such as caffeine may help elucidate the origin behind the slow alkaline HER/HOR kinetics and ways to manipulate it.

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19 citations in Web of Science
18 citations in Scopus

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#7 Affordable and Clean Energy

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Collaboration types
Domestic collaboration
International collaboration
Web of Science research areas
Chemistry, Physical
Engineering, Chemical
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