Kinetic Analysis of pH Dependence in Electrocatalytic Reactions: Strategy and Pitfall

ABSTRACT Electrocatalysis has been investigated as a promising strategy to utilize green electricity to produce renewable fuels, valuable chemicals, and treat pollutants. Electrode kinetic analysis is a potent technique in interrogating reaction mechanisms and evaluating the electrocatalysts. Electron transfer (ET) and proton‐coupled electron transfer (PCET) processes are widely present in reaction networks of electrocatalysis. pH dependence of the kinetics is frequently employed to evaluate whether an elementary step involves proton participation, which is determined by both the reversibility and the specific reactants of electrode reactions. In this article, we discuss the pH dependence of two widely used formulations of the Butler–Volmer kinetics for a model PCET step and highlight a potential pitfall in kinetic analysis. This work aims to provide guiding principles for distinguishing ET and PCET steps via kinetic measurements in electrolytes in a broad range pH values.