From Micro-environments to Macroscopic Effects: How the Alkaline Hydrogen Evolution Reaction Drives Cu Cathodic Corrosion

Cathodic corrosion of copper (Cu) has posed a significant challenge for over a century, impeding various technological progresses such as electrochemical conversion of CO2 (eCO2RR) into fuels and other value-added carbon products. In this study, employing a combined density functional theory (DFT) and kinetic Monte Carlo (kMC) simulation approach, we delve into the atomistic-level mechanism driving this phenomenon in Cu. Our hypothesis posits the pivotal role of the alkaline hydrogen evolution reaction (HER) in facilitating cathodic corrosion in Cu. We rigorously develop a pH-dependent hydroxide (OH) adsorption mechanism and calculate the equilibrium OH coverage (θOH) at varying pH levels, the thermodynamic stability of subsurface oxygen (Osub), as well as the Cu-vacancy mediated diffusion of subsurface oxygens (Osub). Through comprehensive analysis, we establish a correlation among various microenvironments, including oxygen diffusion in subsurface layers, pH-dependent OH adsorption, and Cu dissolution into the electrolyte as (Cu–OH) complexes. Furthermore, our investigation explores the correlation between the surface coordination environment of active sites and cathodic corrosion of Cu. Finally, by integrating DFT-derived thermodynamic data into a kMC model, we successfully predict the formation of experimentally observed corrosion pits on Cu surfaces. This combined approach not only advances our fundamental understanding of Cu cathodic corrosion but also offers insights crucial for developing effective corrosion mitigation strategies.