ToF-SIMS characterization of surface chemical evolution on electrode surfaces educed by electrochemical activation

Abstract

Electrode–electrolyte interfaces are the heart of electrochemical reactions. Activation of electrode surfaces by electrochemical pretreatment can endow electrodes with promoted physicochemical properties to facilitate electron-transfer kinetics during electrochemical reactions. However, comprehensive understanding of the activation mechanism, especially in aspects of surface chemical evolution is limited. Herein, we applied ToF-SIMS in combination with SEM imaging to investigate the electrochemical activation in different stages of gold electrode surfaces in hydrochloric acid solution. The results unraveled the complicated activation mechanism, which not only involved the surface reconstruction with formation of an ultra-thin layer of nanoparticles, but also the significantly altered outmost surface chemistry of the electrodes such as the efficient removal of poisonous surface contamination species. We demonstrate that with the virtues of ultra-high surface sensitivity, shallow information depth, and rich molecular characterization information, ToF-SIMS is a powerful technique for characterization of surface chemistry of electrodes/electrocatalysts. The promising applications of ToF-SIMS will advance the fundamental understanding of the surface chemistry-electrochemical/electrocatalytic activity relationship and facilitate the control and engineering of electrochemical interfaces with promoted performance.