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

Summary

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 (FE_C2+) 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% FE_C2+ and maintained continuous operation for over 50 h at industrial current density. Further investigation demonstrates outstanding FE_C2+ 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.