Anion Exchange Facilitates the In Situ Construction of Bi/BiO Interfaces for Enhanced Electrochemical CO2‐to‐Formate Conversion Over a Wide Potential Window

Abstract Electrochemical reduction of CO 2 (CO 2 RR) into value‐added products is a promising strategy to reduce energy consumption and solve environmental issues. Formic acid/formate is one of the high‐value, easy‐to‐collect, and economically viable products. Herein, the reconstructed Bi 2 O 2 CO 3 nanosheets (BOC R NSs) are synthesized by an in situ electrochemical anion exchange strategy from Bi 2 O 2 SO 4 as a pre‐catalyst. The BOC R NSs achieve a high formate Faradaic efficiency (FE formate ) of 95.7% at −1.1 V versus reversible hydrogen electrode (vs. RHE), and maintain FE formate above 90% in a wide potential range from −0.8 to −1.5 V in H‐cell. The in situ spectroscopic studies reveal that the obtained BOC R NSs undergo the anion exchange from Bi 2 O 2 SO 4 to Bi 2 O 2 CO 3 and further promote the self‐reduction to metallic Bi to construct Bi/BiO active site to facilitate the formation of OCHO * intermediate. This result demonstrates anion exchange strategy can be used to rational design high performance of the catalysts toward CO 2 RR.