Adsorption‐Enhanced Bismuth Oxide Efficiently Convert CO ₂ to Formate Over a Wide Potential Window

ABSTRACT Electrochemical conversion of carbon dioxide (CO ₂ ) into high‐value‐added chemicals using clean energy is a processing method to reduce carbon emissions and store energy. The unsatisfactory adsorption and activation of CO ₂ suppress electrochemical reduction over a narrow potential window. Herein, we synthesized CO ₂ adsorption‐enhanced bismuth oxide nanosheets (syn‐Bi ₂ O ₃ ) using a one‐pot low‐temperature water bath method. The syn‐Bi ₂ O ₃ exhibited marked Faradic efficiency (FE _formate ) over 94% in a wide potential window from −0.43 to −1.31 V versus RHE in the flow cell, and demonstrated an appreciable FE _formate of 94.5% at a partial current density of 661.9 mA cm ⁻² . The in situ spectroscopy and theoretical calculation unraveled the distinct formate production performance of the syn‐Bi ₂ O ₃ catalyst, which was contributed by its adsorption of CO ₂ and promoting the subsequent formation of intermediates. Furthermore, coupled with the simulated solar cell with the 4 layer 3‐cell stacks, the solar to formate and overall solar‐to‐fuel reach 19.34% and 20.23% with over 0.21 A, respectively. This work provides insights into the practical application of electrochemical CO ₂ reduction for formate production driven by solar energy.