Electronic structural modulation of bismuth catalysts induced by sulfur and oxygen co-doping for promoting CO₂...

Carbon dioxide electroreduction into green fuels and value-added chemicals is an attractive method for the utilization of renewable energy to mitigate global warming. High-efficiency catalysts are necessary for mild and efficient conversion via this process. Metal sulfides have shown potential applications in energy conversion and storage thanks to the synergistic effect induced by sulfur and metal atoms. Here, we reported a novel sulfur and oxygen co-doped Bi catalyst derived from bismuth sulfide (Bi₂S₃) for the selective CO₂ electrochemical reduction to formate. As a result, 89.7% formate faradaic efficiency at -1.09 V versus the reversible hydrogen electrode was obtained, and was higher than that obtained by using a pure Bi electrode (84.5%). The characterization and electrochemistry results indicated that co-doping with sulfur and oxygen atoms improved the surface electronic structure of the material, which further affected the adsorption of CO₂ and the formation of reaction intermediates. This study provides a novel catalyst for CO₂-to-formate conversion and also reveals changes in the metal sulfide structure and composition before and after CO₂ electroreduction, which are thought to be the key to enhancing the catalytic performance of bismuth sulfide. A useful basis for the design of metal sulfide-based catalysts is also provided.