Accelerating electrochemical CO2 reduction to multi-carbon products via asymmetric intermediate binding at confined nanointerfaces

CO2 electroreduction to multi-carbon products in acids remains challenging due to the low efficiency and poor stability of C-C coupling. Here, the authors show that asymmetric CO binding at confined nanointerfaces enhances multi-carbon production, improves CO2 utilization, and limits H-2 evolution. Electrochemical CO2 reduction (CO2R) to ethylene and ethanol enables the long-term storage of renewable electricity in valuable multi-carbon (C2+) chemicals. However, carbon-carbon (C-C) coupling, the rate-determining step in CO2R to C2+ 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 CO2-to-C2+ 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 CO2 utilization under acidic conditions. We achieve, as a result, a high 31 +/- 2% single-pass CO2-to-C2+ yield in a mild-acid pH 4 electrolyte with >80% single-pass CO2 utilization efficiency. In a single CO2R flow cell electrolyzer, we realize a combined performance of 91 +/- 2% C2+ Faradaic efficiency with notable 73 +/- 2% ethylene Faradaic efficiency, 31 +/- 2% full-cell C2+ energy efficiency, and 24 +/- 1% single-pass CO2 conversion at a commercially relevant current density of 150 mA cm(-2) over 150 h.

Automated summary

In this study, the authors demonstrate that asymmetric CO binding at confined nanointerfaces can enhance CO2 electroreduction to multi-carbon products. Through alloying strategies, neighbouring binary sites enable improved CO2 utilization and C-C coupling efficiency in acid conditions. These findings offer a potential approach for long-term storage of renewable electricity in valuable multi-carbon chemicals.