Bi₂S₃ nanofiber bunch for highly efficient CO₂ electroreduction to formate at low overpotential

Electrochemical conversion of CO₂ into valuable chemicals represents a promising strategy to alleviate the environmental issues caused by excessive CO₂ levels in the atmosphere. In this work, Bi₂S₃ with different morphologies have been fabricated via facile hydrothermal method to investigate the CO₂ electrochemical reduction process. Compared with Bi₂S₃ nanoflower, Bi₂S₃ nanofiber bunch displays rather efficient electrochemical conversion of CO₂ to formate with the maximum faradaic efficiency of 96% at − 0.75 V vs. reversible hydrogen electrode (RHE). Experimental results demonstrate that the morphology of nanofiber bunch possesses larger surface area, smaller interfacial charge transfer resistance as well as faster initial electron transfer step during the CO₂ electrocatalytic reaction, which are beneficial for the promotion of CO₂ electrocatalytic properties. By partially replacing S with O atom in Bi₂S₃ nanoflower and nanofiber bunch, the electrochemical conversion of CO₂ to CO can be promoted. This work offers valuable insights into the design of efficient electrocatalysts towards selective CO₂ conversion.