On the Coupling of Electron Transfer to Proton Transfer at Electrified Interfaces

Aimin Ge, Georg Kastlunger, Jinhui Meng, Per Lindgren, Jia Song, Qiliang Liu, Alexander Zaslavsky, Tianquan Lian, Andrew A. Peterson

Research output: Contribution to journalArticle

Abstract

Many electrochemical processes are governed by the transfer of protons to the surface, which can be coupled with electron transfer; this electron transfer is in general non-integer and unknown a priori, but is required to hold the potential constant. In this study, we employ a combination of surface spectroscopic techniques and grand-canonical electronic-structure calculations in order to rigorously understand the thermodynamics of this process. Specifically, we explore the protonation/deprotonation of 4-mercaptobenzoic acid as a function of the applied potential. Using grand-canonical electronic-structure calculations, we directly infer the coupled electron transfer, which we find to be on the order of 0.1 electron per proton; experimentally, we also access this quantity via the potential-dependence of the pKa. We show a striking agreement between the potential-dependence of the measured pKa and that calculated with electronic-structure calculations. We further employ a simple electrostatics-based model to show that this slope can equivalently be interpreted to provide information on the degree of coupled electron transfer or the potential change at the point of the charged species.

Original languageEnglish
Pages (from-to)11829-11834
Number of pages6
JournalJournal of the American Chemical Society
Volume142
Issue number27
DOIs
Publication statusPublished - 2020 Jul 8
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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