charge transfer, electrochemical reduction of CO2, hierarchically silver sub‐nanosheets, hollow fiber gas diffusion electrode, Materials of engineering and construction. Mechanics of materials, TA401-492

Electrochemical reduction of CO2 (CO2RR) is an effective strategy to mitigate carbon emission effects and store renewable electricity in value‐added feedstocks, but it still suffers low production rate and current density. A nanostructured catalyst offers opportunities to enhance CO2RR activity by contributing numerous active sites and promoting charge transfer. Herein, a Cu hollow fiber gas diffusion electrode (HFGDE) with silver sub‐nanosheets on a zinc nanosheet structure to produce CO is reported. Compared to the HFGDE only possessed zinc nanosheet structure, the as‐prepared HFGDE with hierarchical sub‐nano AgZn bimetal nanosheets exhibits a twice‐partial current density of CO and a CO production rate at the applied potential −1.3 V (versus reversible hydrogen electrode). The unique Ag sub‐nanosheets interconnected Zn nanosheets provide multiple charge transfer channels, and the synergistic effect between Ag and Zn improves the adsorption binding energy of COOH* intermediate, resulting in a lower charge transfer resistance and fast CO2RR kinetics to produce CO. This research demonstrates the high potential of nanoengineering electrocatalysts for HFGDE to achieve highly efficient CO2 reduction.