In Situ Reconstruction of a Cu(100) Surface for Promoted C–C Coupling in CO ₂ Electroreduction from First-Principles Multiscale Modeling

Copper (Cu) has attracted significant interest due to its ability to reduce carbon dioxide (CO2) to multicarbon products (C2+) in electrocatalysis. C–C coupling is the key step in the formation of C2+. Recent in situ experiments have shown significant surface reconstructions of Cu in electrocatalytic carbon dioxide reduction reaction (eCO2RR) conditions, yet the atomic structures of the restructuring surface and its combined effect with interfacial water on the reaction mechanism are poorly understood. In this work, we introduced a multiscale modeling algorithm to simulate the real-time reconstruction process of a Cu(100) surface (as large as ∼35 nm × 35 nm) for 300 s using the combined grand canonical Monte Carlo (GCMC) and environmental kinetic Monte Carlo (EKMC) method. Statistical analysis reveals that zigzag-edged subnano-ribbons composed of 4-adatom units dominate the in situ formed clusters at −0.2 V vs RHE (reversible hydrogen electrode). We further use a slow-growth approach based on ab initio molecular dynamics (AIMD) to unveil the effect of the 4-adatom motif on CO–CO coupling in aqueous solution. This motif significantly enhances CO dimerization, achieved through interfacial hydrogen bonding, which modulates CO to a moderate activation status. Our work underscores the non-negligible role of reconstructed structures on Cu(100) at the atomic scale in electrocatalysis.