In Situ Growth of Hierarchical Silver Sub-Nanosheets on Zinc Nanosheets-Based Hollow Fiber Gas-Diffusion Electrodes for Electrochemical CO2 Reduction to CO

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.