Potential-Dynamic Surface Chemistry Controls the Electrocatalytic Processes of Ethanol Oxidation on Gold Surfaces

Electrocatalysis has various important applications, especially fuel cells. As a key element in electrocatalysis, the surface chemistry of electrocatalysts may strongly influence the catalytic activity and reaction mechanism, the fundamental understanding of which would provide guidance for designing high-efficiency catalysts. Herein, we utilized our recently developed in situ liquid SIMS approach to investigate the electrocatalytic oxidation of ethanol on gold surfaces in alkaline environments involved in direct alcohol fuel cells. Formation of adsorbed hydroxide intermediates on the gold surfaces upon electro-oxidation was molecularly witnessed under operando conditions, the evolution of which was revealed to govern the electrocatalytic processes. Moreover, the hydroxide intermediates as active sites participated in the reaction by transferring nucleophilic hydroxyl groups into the adjacent ethoxy molecules. This work brings new light into electrocatalytic research and will facilitate the improvement of catalytic systems on the basis of a surface chemistry–catalytic performance relationship.