Model Systems for Understanding Ion-Transfer Kinetics in Corrosion

Abstract

Copper is a valuable material in renewable energy technologies, such as catalysts on gas diffusion electrodes in electrochemical devices for the electrochemical reduction of carbon dioxide (CO2) to high-value products. By understanding the kinetics of ion-transfer in copper corrosion and deposition processes, we can gain a better understanding of the durability of devices that employ copper. Measurement of ion-transfer kinetics of bulk metal materials has a magnitude of challenges, increasing the difficulty of precisely analyzing the fundamentals of the processes. To assuage these concerns and obtain a more representative microscopic picture of Cu corrosion processes while investigating the effect of the anions on copper durability, we created several model microenvironments that employ copper underpotential deposition (UPD) on a well-ordered Au[111] surface: 1) a model system in sulfuric acid; 2) a bridging environment (methanesulfonic acid), and 3) a model microenvironment for gas diffusion (Nafion electrolyte). After analyzing these three systems, we expanded our models to investigate the effects of steric by adding ethanesulfonic acid and the effects of electronegativity by adding triflic acid. Our results demonstrate the effect of supporting anions on the ion-transfer kinetics of Cu UPD corrosion and deposition processes to give a better understanding of fundamental kinetics and mechanisms in gas diffusion environments. Figure 1