Anion-Mediated In SituReconstruction of the Bi2MoO6Precatalyst for Enhanced Electrochemical CO2Reduction over a Wide Potential Window

Electrochemical CO2reduction reaction (eCO2RR) is a viable approach to achieve carbon neutrality. Bismuth-based electrocatalysts demonstrate exceptional selectivity in CO2-to-formate conversion, but their reconstruction mechanisms during the eCO2RR remain elusive. Herein, the reconstruction processes of bismuth molybdate (Bi2MoO6) nanoplates are elucidated during the eCO2RR. Operandoand ex situmeasurements reveal the in situpartial reduction of Bi2MoO6to Bi metal, forming Bi@Bi2MoO6at negative potentials. Meanwhile, CO32–ions in the electrolyte spontaneously exchange with MoO42–in Bi2MoO6. The obtained Bi@Bi2MoO6/Bi2O2CO3delivers a formate Faradaic efficiency (FE) of 95.2% at −1.0 V. Notably, high formate FEs (>90%) are maintained within a wide 500 mV window. Although computational calculations indicate a higher energy barrier for *OCHO formation on Bi2O2CO3, the prevention of excessive reduction to metal Bi significantly enhances long-term stability. Furthermore, the CO32–ion exchange process occurs in various 2D Bi-containing precatalysts, which should be emphasized in further studies.