Voltage-Dependent Electrochemical Carbon Dioxide Reduction Mechanism Unveiled by Kinetic Monte Carlo Simulation

The voltage-dependent dynamic evolution of the electrocatalytic carbon dioxide reduction reaction (CO₂RR) on Cu-based catalysts is still unclear. Herein, a Kinetic Monte Carlo (KMC) model that tracks the evolution of the CO₂RR on the Cu (111)/(100) surface is developed. Using the Density Functional Theory calculated energetics of 178 elementary reactions in CO₂RR toward C₁-C₂ multispecies production, the KMC model predicted CO₂RR linear sweep voltammetry and potential-dependent product distribution that agree well with experimental observations. Degree of rate control analysis reveals that, on Cu (111), the primary hydrocarbon product is C₁ species CH₄, and as the working potential increases, its rate-determining step (RDS) changes from CO hydrogenation toward the CHO* formation step into the COH* formation step. The Cu (100) surface is more active toward C₂H₄ and CH₃CH₂OH production with CO* symmetric coupling step as RDS. This KMC model provides important insights into the CO₂RR dynamics on Cu catalysts.