Oxygen vacancy-rich CeOx-Bi2O2CO3 nanosheets for enhancing electrocatalytic reduction of CO2 to formate

Bismuth (Bi)-based materials show the great potential for electrochemical reduction of CO2 to formate due to their low toxicity and accelerating *OCHO production, but there are many challenges in their activity and practicality. Here we report the preparation of CeOx-Bi2O2CO3 nanosheet catalysts with abundant oxygen vacancies by introducing the more economical rare earth element cerium (Ce), which exhibits better performance in the conversion of CO2RR to formate. CeOx-Bi2O2CO3 could maintain high activity within a wide potential window to obtain more than 90% formate selectivity and stability for 17 h in H-type cell and improve the Faradaic efficiency of formate in the flow cell. In situ IR and Density functional theory (DFT) calculations indicate a significant synergistic effect on CO2RR between CeOx and Bi2O2CO3, because CeOx can modulate the electron cloud density of Bi and improve the adsorption of key intermediates. Also, a large number of unsaturated sites could lower the energy barrier of *OCHO production, inhibit H2 production, and accelerate the electron transfer to generate formate. This work explores the reaction pathway of formate production from Ce-doped Bi-based catalysts and provides new insights into the design of oxygen vacancy-rich Bi-based catalysts for efficient CO2RR.