Regulating C–C Coupling via CO Generation and Utilization in CO ₂ RR on Ag–Cu Catalysts

Ag–Cu tandem catalysis provides an effective strategy to enhance C2+ selectivity in the electrochemical CO2 reduction reaction (CO2RR) by integrating CO generation and utilization for C–C coupling. Here, we report a series of Ag@Cu2O, Ag@CuO, and Ag@CuO-BDC core–shell catalysts designed to regulate the CO generation, Cu-oxidation states, and surface structures. The Ag@Cu2O catalysts exhibit pronounced tandem effects, suppressing CH4 formation while enhancing the C–C coupling on the Cu sites. Notably, Ag@Cu2O-30 achieves a high C2H4/CH4 Faradaic efficiency ratio of 6.5 at −1.8 V (vs RHE) with an increased C2H4 partial current density of 12.3 mA cm–2. Oxidation to Ag@CuO further modifies the Cu species distribution, facilitating CO and CO2 diffusion while reducing H2 formation. Moreover, constructing Cu-BDC-MOF followed by electrochemical reconstruction generates additional oxygen vacancies and stabilizes Cu+ species, enhancing C2H4 selectivity and stability but with increased CH4 formation and reduced current density. This study highlights Ag–Cu tandem catalysis and structural regulation of Cu as effective strategies for achieving selective reduction of CO2 toward C2H4.