Metal doping promotes the efficient electrochemical reduction of CO2 to CO in CuO nanosheets

Electrocatalytic reduction of carbon dioxide to carbon monoxide is an effective strategy to solve renewable energy storage and carbon neutral-energy cycle, but the ability of selective reduction to carbon monoxide products still needs to be improved. This work reported a strategy to promote the electrochemical reduction of carbon dioxide to carbon monoxide in CuO nanosheets by metal doping. CuO, CuO/Bi, CuO/In, and CuO/Sn electrocatalysts were prepared by a simple hydrothermal method. According to the electrochemical test, the Faraday efficiencies of CuO, CuO/Bi, CuO/In and CuO/Sn catalysts were 21.29%, 37.25%, 87.88% and 92.44%, respectively, at the potential of −0.8 V vs. RHE. In addition, the electrocatalytic carbon dioxide reduction products of CuO/In and CuO/Sn catalysts are only hydrogen and carbon monoxide products, and the selectivity of carbon monoxide is almost 100%. The results showed that doping of Bi, In, and Sn in CuO significantly enhanced the activity and selectivity of electrocatalytic carbon dioxide reduction to carbon monoxide at low overpotential, while greatly inhibiting the occurrence of hydrogen evolution reaction. In addition, the stability of CuO/Sn catalyst was tested in 0.1 mol/L KHCO3 electrolyte, and the current density remained unchanged within 6 h, indicating that the prepared catalyst has excellent stability.