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 (CO 2 ) to multicarbon products (C 2+ ) in electrocatalysis. C–C coupling is the key step in the formation of C 2+ . Recent in situ experiments have shown significant surface reconstructions of Cu in electrocatalytic carbon dioxide reduction reaction (eCO 2 RR) 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.