Phosphorus Coordination in Second Shell of Single-Atom Cu Catalyst toward Acetate Production in CO Electroreduction

It is challenging to achieve highly efficient CO–CO coupling toward C2 products in electrochemical CO and CO2 reductions on single-atom catalysts (SACs). Herein, we report a modulation strategy of phosphorus coordination in the second shell of Cu SACs with a Cu–N4 structure (Cu–N4–P4/C4) and demonstrate experimentally and theoretically the CO–CO coupling through an Eley–Rideal mechanism in electrochemical CO reduction (COR). Remarkably, the Cu SACs exhibit a selectivity of 63.9% toward acetate production in alkaline media on a gas diffusion electrode. Operando synchrotron-based X-ray absorption spectroscopy confirms the robust Cu–N4–P4/C4 structure of the Cu SACs against the harsh electrochemical reduction conditions throughout the electrochemical COR, instead of forming Cu clusters for Cu–N4 configuration, enabling an excellent COR performance toward acetate. This work not only unravels a new mechanism for CO–CO coupling toward C2 products in COR but also offers a novel strategy for SAC regulation toward multicarbon production with high activity, selectivity, and durability.