Improving the Accuracy of Modelling CO₂ Electroreduction on Copper Using Many-Body Perturbation Theory

Copper (Cu) remains the most important metal catalyst for the carbon dioxide reduction reaction (CO₂ RR) into C₂ products. Due to limited evidence from in situ experiments, mechanistic studies are often performed in the framework of density functional theory (DFT), using functionals at the generalized gradient approximation (GGA) level, which have fundamental difficulties to correctly describe CO adsorption and surface stability. We employ the adiabatic connection fluctuation dissipation theorem within the random phase approximation (RPA), in combination with the linearized Poisson-Boltzmann equation to describe solvation effects, to investigate the mechanism of CO₂ RR on the Cu(100) facet. Qualitatively different from the DFT-GGA results, RPA results propose the formation of *OCCHO as the potential determining step towards C₂ products. The results suggest that it is important to use more accurate methods like RPA when modeling reactions involving multiple CO-related species like CO₂ RR.