Cuprous Sulfide Nanoarrays for Selective Electroreduction of CO2 to Formate at Low Overpotentials

•Cu2S nanoarrays were successfully constructed on a Cu foil.•The electrocatalytic CO2 reduction reaction performance of Cu2S was evaluated.•Cu2S can selectively reduce CO2 to formate at low overpotentials.•The stability of Cu2S under CO2RR conditions was confirmed by XRD, XPS, and in-situ Raman spectrum. Transformation of carbon dioxide to useful fuels or chemicals is desirable to build up a sustainable society. In this study, we demonstrate that Cu2S has great potential for electrochemical CO2 reduction. They enable the selective CO2 reduction to formate starting at a low overpotential (∼ 120 mV), with high current density (over -20 mA/cm2 at -0.89 VRHE), and good Faradaic efficiency (>75%) over a broad potential window (-0.7 VRHE to -0.9 VRHE). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and in-situ Raman spectroscopy studies reveal that Cu2S catalysts are electrochemically stable under the reaction conditions. Further-more, Cu2S catalysts show excellent durability without deactivation following more than 15 cycles (1.0 h per cycle) of operation. [Display omitted]