Lowering C−C coupling barriers for efficient electrochemical CO2 reduction to C2H4 by jointly engineering single Bi atoms and oxygen vacancies on CuO

Electrochemical CO2 reduction (ECR) to commodity chemicals offers a promising way for mitigating the greenhouse effect and driving the transition from fossil-fuel dependence to a sustainable economy. To this end, the design and development of active and robust electrocatalysts is key. Here we report for the first time that incorporation of bismuth (Bi) single atoms on defective CuO could significantly enhance the ECR reaction to C2H4 by decreasing C–C coupling barriers. The overpotential for C2H4 production is lowered by at least 50 mV, along with a two-fold improvement in the faradaic efficiency, reaching 60% at 400 mA cm−2. The high performance is maintained even after 20 h of consecutive electrolysis. Control experiments along with density functional theory calculations suggest that the joint incorporation of Bi and oxygen vacancies greatly promotes CO2 adsorption and lowers C–C coupling energy barriers, thereby improving the C2H4 selectivity.