In-situ constructing Cu1Bi1 bimetallic catalyst to promote the electroreduction of CO2 to formate by synergistic electronic and geometric effects

Electrochemical CO2 reduction to formate is a potential approach to achieving global carbon neutrality. Here, Cu1Bi1 bimetallic catalyst was prepared by a co-precipitation method. It has a ginger like composite structure (CuO/CuBi2O4) and exhibited a high formate faradaic efficiency of 98.07% at –0.98 V and a large current density of –56.12 mA·cm−2 at –1.28 V, which is twice as high as Bi2O3 catalyst. Especially, high selectivity (FEHCOO– > 85%) is maintained over a wide potential window of 500 mV. In-situ Raman measurements and structure characterization revealed that the reduced Cu1Bi1 bimetallic catalyst possesses abundant Cu-Bi interfaces and residual Bi-O structures. The abundant Cu-Bi interface structures on the catalyst surface can provide abundant active sites for CO2RR, while the Bi-O structures may stabilize the CO2*– intermediate. The synergistic effect of abundant Cu-Bi interfaces and Bi-O species promotes the efficient synthesis of formate by following the OCHO* pathway.