Copper vulcanization realizes selective carbon dioxide reduction to formate

Herein, we demonstrate that the vulcanization of copper nanosheets (Cu2S NSs) can realize selective electrochemical carbon dioxide reduction (CO2RR) to formate (HCOOH). Results from experiments and in situ infrared spectroscopy reveal that Cu2S NSs favor CO2 reduction along the HCOO* pathway, leading to the selective formation of HCOOH. Impressively, the Faraday efficiency (FE) of HCOOH surpasses 70% in a broad potential range from -0.84 to -1.21 V versus (vs.) reversible hydrogen electrode (RHE), with a maximum value of 82%.