Identification of Cu0/Cu+/Cu0 interface as superior active sites for CO2 electroreduction to C2+ in neutral condition

Cu-based catalysts are boosting electrocatalysts in CO2 reduction reactions to high-value multicarbon (C2+) products. Because of the unstable Cu+ species and the unclear microscopic structure in reactions, Cu-based catalysts still face significant challenges of low selectivity and poor durability at high current density. Herein, we report a thermodynamically driven comproportionation strategy for forming a Cu0/Cu+/Cu0 interface to stabilize Cu+ species. When tested in a flow cell containing neutral electrolyte, the sample showed a high C2+ products Faradaic efficiency (FEC2+) of 92.3% at a partial current density of 276.9 mA cm−2. In a membrane electrode assembly, the sample achieved a 90.1% FEC2+ and maintained continuous operation for over 50 h at industrial current density. Further investigation demonstrates outstanding FEC2+ of >80% at a large industrial current of 10 A. Mechanism studies reveal that the Cu0/Cu+/Cu0 interface lowers the energy barrier for C–C coupling in the reaction, thus facilitating the conversion of CO2 to C2+ products.