Enhanced electrochemical CO2 reduction to ethylene over CuO by synergistically tuning oxygen vacancies and metal doping

Electrochemical CO 2 reduction to multi-carbon fuels and chemicals is intriguing but remains a challenge. Here, we report that a combination of Sn doping and creation of oxygen vacancies (V O ) can synergistically boost CO 2 reduction to C 2 H 4 over CuO nanosheets with an onset potential of −0.7 V (versus reversible hydrogen electrode). The activity and selectivity of CuO can be easily tuned by manipulation of Sn dopant and V O contents. The Faradaic efficiency toward C 2 H 4 formation over Sn-doped CuO(V O ) approaches 48.5% ± 1.2%, which maintains stability over 24 h at a mild overpotential, in contrast to a maximum of 26.8% ± 2.2% over pristine CuO. The Sn-doped CuO(V O ) catalyst presents an approximately 2.3-fold improvement in C 2 H 4 current compared to undoped CuO at similar overpotentials. Theoretical calculations further show that doping of Vo-enriched CuO surface by Sn lowers the dimerization energy of adsorbed CO intermediate, thereby promoting C–C coupling to yield C 2 H 4 .