Efficient electrocatalytic reduction of CO2 to CO via mechanochemical synthesized copper-based composite metallic oxide catalyst

Electrocatalysis serves as a highly effective approach to both mitigate greenhouse gas emissions and produce high-value chemicals. Copper-based catalysts have garnered considerable attention due to their immense potential in this domain. Improving the selectivity and activity through optimizing preparation strategies is of paramount importance. In this study, the mechanochemical method was first used for preparing copper-based composite metallic oxide electrocatalysts. Spherical CuO, Sn-CuO, and Sn-In-CuO catalysts were prepared, and their electrochemical CO2 performance was evaluated. Among them, the Sn-In-CuO catalyst demonstrated the best performance in reducing CO2 to CO products. Within the potential range of -0.6 V to -1.1 V vs. RHE, the Faradaic efficiency of the CO product was consistently above 93.56%, with a maximum Faradaic efficiency of 96.11% achieved at -0.9 V vs. RHE. Sn-In-CuO also exhibits good stability with high Faradaic efficiency of CO above 87.97% for a duration of 6 h under the potential of -0.6 V vs. RHE in a 0.1 M KHCO3 electrolyte. The excellent performance is speculated to be attributed to the generation of a large number of defects and the introduction of metal doping, which increases the number of active sites through the mechanochemical method.