Partial sulfuration-induced defect and interface tailoring on bismuth oxide for promoting electrocatalytic CO₂ reduction

Defect and interface engineering is a powerful strategy to tune the electronic structure and adsorption behavior of electrocatalysts, boosting the performance of the electrocatalytic CO₂ reduction reaction (eCO₂RR). Herein, we construct a hybrid electrocatalyst, Bi₂S₃-Bi₂O₃@rGO, with a large amount of defects (oxygen vacancies etc.) and a specific interface between bismuth sulfide (Bi₂S₃) and bismuth oxide (Bi₂O₃) by a partial precipitation conversion method. Both experimental results and theoretical calculations reveal that the Bi₂S₃-Bi₂O₃ interface drastically lowers the formation energy of HCOO∗, in favor of the production of formate (HCOOH) over CO, promoting the conversion of CO₂ to HCOOH. The as-prepared electrocatalyst shows excellent electrocatalytic activity to generate HCOOH with a high faradaic efficiency of over 90% and a low overpotential of 700 mV, as well as excellent durability for more than 24 h.