Ultrafine CuS anchored on nitrogen and sulfur Co-doped graphene for selective CO2 electroreduction to formate

Electrochemical conversion of CO2 into hydrocarbons can effectively alleviate the energy crisis and promote carbon cycle. Herein, we report that small-size CuS nanoparticles are confined in nitrogen and sulfur co-doped reduced graphene oxide (CuS/N,S-rGO) for electrochemically reducing CO2 to formate. Specifically, the CuS/N, S-rGO electrode achieves maximum Faradaic efficiency of 82% for formate formation at-0.63 V versus the reversible hydrogen electrode (RHE). Moreover, this catalyst exhibits a stable performance during 20 h-electrolysis. Experiments demonstrate that the doping of nitrogen and sulfur can create an abundance of active sites on the graphene nanosheets to accelerate the CO2 reduction reaction (CO2RR). The CuS/N,S-rGO electrode exhibits excellent performance for CO2RR is attributed to the synergistic effect between N,S-rGO and CuS, and graphene can improve stability of composite. This work provides an efficient electrocatalyst for CO2RR and offers a facile and environmental friendly approach to synthesize small-size Cu-based composites.