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 C 2+ selectivity in the electrochemical CO 2 reduction reaction (CO 2 RR) by integrating CO generation and utilization for C–C coupling. Here, we report a series of Ag@Cu 2 O, Ag@CuO, and Ag@CuO-BDC core–shell catalysts designed to regulate the CO generation, Cu-oxidation states, and surface structures. The Ag@Cu 2 O catalysts exhibit pronounced tandem effects, suppressing CH 4 formation while enhancing the C–C coupling on the Cu sites. Notably, Ag@Cu 2 O-30 achieves a high C 2 H 4 /CH 4 Faradaic efficiency ratio of 6.5 at −1.8 V (vs RHE) with an increased C 2 H 4 partial current density of 12.3 mA cm –2 . Oxidation to Ag@CuO further modifies the Cu species distribution, facilitating CO and CO 2 diffusion while reducing H 2 formation. Moreover, constructing Cu-BDC-MOF followed by electrochemical reconstruction generates additional oxygen vacancies and stabilizes Cu + species, enhancing C 2 H 4 selectivity and stability but with increased CH 4 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 CO 2 toward C 2 H 4 .