Boron Dopant Induced Electron‐Rich Bismuth for Electrochemical CO2 Reduction with High Solar Energy Conversion Efficiency

Electrochemical CO2 reduction to formate offers a mild and feasible pathway for the utilization of CO2, and bismuth is a promising metal for its unique hydrogen evolution reaction inhibition. Reported works of Bi‐based electrodes generally exhibit high selectivity while suffering from relatively narrow working potential range. From the perspective of electronic modification engineering, B‐doped Bi is prepared by a facile chemical reduction method in this work. With B dopant, above 90% Faradaic efficiency for formate over a broad window of working potential of −0.6 to −1.2 V (vs. reversible hydrogen electrode) is achieved. In situ Raman spectroscopy, X‐ray adsorption spectroscopy, and computational analysis demonstrate that the B dopant induces the formation of electron‐rich bismuth, which is in favor of the formation of formate by fine‐tuning the adsorption energy of *OCHO. Moreover, full‐cell electrolysis system coupled with photovoltaic device is constructed and achieves the solar‐to‐formate conversion efficiency as high as 11.8%. Efficient electrochemical CO2 reduction to formate is economically viable. Herein, the electron‐rich bismuth is obtained by introducing boron atoms. This B‐doped Bi has high Faradaic efficiency for formate (above 90%) over a wide range of working potential and large current density. Moreover, the solar‐to‐formate conversion efficiency achieves to be 11.8%.