Boosting Electrochemical Reduction of CO₂ at a Low Overpotential by Amorphous Ag‐Bi‐S‐O Decorated Bi⁰ Nanocrystals

Abstract

Abstract Bimetal‐S‐O composites have been rarely researched in electrochemical reduction of CO 2 . Now, an amorphous Ag‐Bi‐S‐O decorated Bi 0 catalyst derived from Ag 0.95 BiS 0.75 O 3.1 nanorods by electrochemical pre‐treatment was used for catalyzing eCO 2 RR, which exhibited a formate FE of 94.3 % with a formate partial current density of 12.52 mA cm −2 at an overpotential of only 450 mV. This superior performance was attributed to the attached amorphous Ag‐Bi‐S‐O substance. S could be retained in the amorphous region after electrochemical pre‐treatment only in samples derived from metal‐S‐O composites, and it would greatly enhance the formate selectivity by accelerating the dissociation of H 2 O. The existence of Ag would increase the current density, resulting in a higher local pH, which made the role of S in activating H 2 O more significantly and suppressed H 2 evolution more effectively, thus endowing the catalyst with a higher formate FE at low overpotentials.