Regulating C-C Coupling via CO Generation and Utilization in CO₂RR 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.