Regulating the Rate‐Determining Step of Bismuth Electrocatalysts by Directional Facet Reconstruction for Efficient CO ₂ Reduction

Abstract Bismuth (Bi)‐based catalysts hold promise for electrochemical CO 2 ‐to‐formic acid conversion, yet limited mechanistic understanding hinders the rational design of active sites. Here, the facile modification of Bi metal electrocatalysts by selenium (Se) dispersions strategy is demonstrated, which can effectively increase the selectivity and widen the potential window of the carbon dioxide reduction reaction (CO 2 RR). The Faraday efficiency of formate (FE formate ) in the prepared Se‐Bi catalyst near 100% with a large potential window of 600 mV. In particular, the partial current density of formate reaches −166.9 mA cm −2 with the long‐term stability exceeding 72 hours. To elucidate the underlying mechanism, synchrotron radiation–based multitechniques (SRMS), including in situ X‐ray diffraction, in situ X‐ray absorption fine structure, in situ Raman spectroscopy, and in situ attenuated total reflection surface‐enhanced infrared absorption spectroscopy, are employed. It is found that the Se imported changed the rate‐determining step to enhance the performance by facet order reconstruction. The anion‐enhancement effect is attributed to the catalyst crystal orientation reconstruction behavior with changing rate‐determining step. This work proposes a crystal plane engineering strategy through non‐metallic element doping to achieve precise manipulation of the rate‐determining step in catalytic processes, offering a new strategy for designing efficient CO 2 RR catalysts.