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%.
Keywords: B dopant; broad working potential window; electrochemical CO 2 reduction; electron-rich Bi; high energy conversion efficiency; in situ Raman.
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