▎ 摘　　要

NOVELTY - Preparing bismuth sulfide-carbon nanomaterial comprises stirring the sulfur source and the functionalized carbon nanomaterial at room temperature to obtain a mixed solution A, dispersing the bismuth source in the dilute acid solution, and stirring at room temperature to obtain a uniform mixed solution B, adding mixed solution B into the mixed solution A at a uniform speed and centrifuging. The nano-carbon material is biomass charcoal, reduced graphene oxide or carbon nanotubes and the sulfur source is thioacetamide. The bismuth source is bismuth nitrate, bismuth acetate, bismuth sulfate, bismuth carbonate or bismuth halide. USE - The method is useful for preparing bismuth sulfide-carbon nanomaterial. ADVANTAGE - The bismuth sulfide-carbon nano-material has a unique structure, good conductivity and rich interface, high stability, characteristics the electro-catalysis reducing carbon dioxide producing formate, exhibits excellent electro- catalytic activity and stability, selectivity of formate is close to 100% and the continuous electrolysis is nearly 80 hours, and the catalyst is not inactivated obviously. The material can reduce the production cost and improve the performance of the electro catalytic reduction of the carbon dioxide formate. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: bismuth sulfide-carbon nano-material; and preparation method of formate salt