Sulfur and Nitrogen Co-Doping Bismuth-Based Catalysts for Selective Electroreduction of CO2 to Formate

Since the greenhouse effect is an urgent problem, the conversion of greenhouse gas CO2 into valuable chemicals and low-carbon fuels by electrocatalysis is a promising way and has attracted comprehensive attention. In recent years, metal sulfides have shown catalytic performance for electrocatalytic reduction of CO2. However, the existing catalysts still face the problems such as insufficient activity, poor conductivity and low stability. Here, we synthesized a bismuth-based catalyst doped with sulfur by electroreducing Bi2S3 precursor, which is obtained by one-pot hydrothermal reaction, and simultaneously modified catalyst with nitrogen atoms using N,N-Dimethylformamide (DMF) as nitrogen source. The experimental results show that maximum faradaic efficiency of formate can reach 85% at -0.96V (vs. RHE) with the largest current density of 30mA/cm2 and a long-term tolerance in reduction process. Combined with other experimental results, the better catalytic performance is mainly attributed to the improvement of the electron structure on the surface of the catalyst by sulfur and nitrogen co-doping. This work not only provides a simple way of sulfur and nitrogen co-doping, but also explores the transformation of Bi2S3 during electrochemical reduction, further providing an idea for the design of catalysts from metal sulfides.