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%.

Automated summary

By using a simple chemical reduction method, B-doped Bi electrodes were prepared in this work, achieving over 90% Faradaic efficiency for formate. Experimental results show that the B dopant facilitates the formation of electron-rich bismuth, promoting the formation of formate. Furthermore, coupling a full-cell electrolysis system with a photovoltaic device resulted in a high solar-to-formate conversion efficiency of 11.8%.