Accelerating electrochemical CO 2 reduction to multi-carbon products via asymmetric intermediate binding at confined nanointerfaces.

Electrochemical CO 2 reduction (CO 2 R) to ethylene and ethanol enables the long-term storage of renewable electricity in valuable multi-carbon (C 2+ ) chemicals. However, carbon-carbon (C-C) coupling, the rate-determining step in CO 2 R to C 2+ conversion, has low efficiency and poor stability, especially in acid conditions. Here we find that, through alloying strategies, neighbouring binary sites enable asymmetric CO binding energies to promote CO 2 -to-C 2+ electroreduction beyond the scaling-relation-determined activity limits on single-metal surfaces. We fabricate experimentally a series of Zn incorporated Cu catalysts that show increased asymmetric CO* binding and surface CO* coverage for fast C-C coupling and the consequent hydrogenation under electrochemical reduction conditions. Further optimization of the reaction environment at nanointerfaces suppresses hydrogen evolution and improves CO 2 utilization under acidic conditions. We achieve, as a result, a high 31 ± 2% single-pass CO 2 -to-C 2+ yield in a mild-acid pH 4 electrolyte with >80% single-pass CO 2 utilization efficiency. In a single CO 2 R flow cell electrolyzer, we realize a combined performance of 91 ± 2% C 2+ Faradaic efficiency with notable 73 ± 2% ethylene Faradaic efficiency, 31 ± 2% full-cell C 2+ energy efficiency, and 24 ± 1% single-pass CO 2 conversion at a commercially relevant current density of 150 mA cm -2 over 150 h.