First-Principles-Based Prediction of Electrochemical Oxidation and Corrosion of Copper under Multiple Environmental Factors

We present the broadly important immunity, passivation, and corrosion behavior of copper subjected to multiple environmental factors, e.g., solution pH, electrode potential, temperature, and pressure, assessed through density functional theory-calculated electrochemical Pourbaix diagrams. The existing discrepancies between thermodynamically predicted and electrochemically observed behaviors of copper in aqueous electrochemical conditions are addressed. Corrosion phases are found to compete with solid copper precipitates at small applied potentials near neutral pHs. Elevated temperatures initiate driving forces that increasingly favor corrosion products over passivating oxides. We predict the prolonged stability of solid phases at non-standard-state conditions below ≈200 °C. At temperatures close to 300 °C and above, corrosion should progress at all pHs for neutral and positive applied potentials. Moreover, we report the pressure dependence of our Pourbaix diagrams at 500 and 5000 bar, which shows that pressure alters the predominance of specific ionic species. Finally, to reduce the needed computational resources and utilize high-fidelity density functional theory (DFT) methods, we introduce a revised correct relative chemical potential (CRCP) scheme that leverages highly accurate hybrid density functionals that include nonlocal Fock exchange. Our results and discussion of the methodology provide insight into using first-principles calculations to obtain non-standard-state Pourbaix diagrams for understanding oxidation and corrosion under extreme conditions.