Weak *CO-Binding Dopants in Cu-Based Single-Atom Alloys Serving as Diffusion-Assisting Mediators to Facilitate C–C Coupling

Copper-based single-atom alloy (SAA) catalysts exhibit tunable C–C coupling behavior during CO2 reduction, governed by dopant-dependent metal–carbon (M–C) interactions. Combining density functional theory (DFT) calculation and ab initio molecular dynamics (AIMD) simulation, this study systematically investigates dopant effects across three C–C coupling pathways: *CO+*CO, *CO+*COH, and *CO+*CHO. Compared to *COH and *CHO, *CO is identified as the primary migratory intermediate governing coupling kinetics due to its weak adsorption and low coordination number. Strong M–C interactions (e.g., Ni-doped Cu) anchor *CO at dopant sites, suppressing migration and increasing C–C coupling barriers. Conversely, weak M–C interactions (e.g., Zn-doped Cu) destabilize *CO adsorption, enabling its migration between Cu sites and reducing C–C coupling energy barriers compared to pristine Cu. We propose an assisted-diffusion mechanism in which dopants with weak M–C interactions promote *CO migration for C–C coupling by acting as diffusion mediators rather than active adsorption sites, thereby enhancing the Faraday efficiency of the overall multicarbon product. These findings provide atomic-scale insights for designing high-activity Cu-based SAAs via the targeted modulation of dopant–C interactions.