Sn-Doped Bi2O3nanosheets for highly efficient electrochemical CO2reduction toward formate production

Electrocatalytic CO2 reduction to formate is considered as a perfect route for efficient conversion of the greenhouse gas CO2 to value-added chemicals. However, it still remains a huge challenge to design a catalyst with both high catalytic activity and selectivity for target products. Here we report a unique Sn-doped Bi2O3 nanosheet (NS) electrocatalyst with different atomic percentages of Sn (1.2, 2.5, and 3.8%) prepared by a simple solvothermal method for highly efficient electrochemical reduction of CO2 to formate. Of them, the 2.5% Sn-doped Bi2O3 NSs exhibited the highest faradaic efficiency (FE) of 93.4% with a current density of 24.3 mA cm-2 for formate at -0.97 V in the H-cell and a maximum current density of nearly 50 mA cm-2 was achieved at -1.27 V. The formate FE is stable maintained at over 90% in a wide potential range from -0.87 V to -1.17 V. Electrochemical and density functional theory (DFT) analyses of undoped and Sn doped Bi2O3 NSs indicated that the strong synergistic effect between Sn and Bi is responsible for the enhancement in the adsorption capacity of the OCHO* intermediate, and thus the activity for formate production. In addition, we coupled 2.5% Sn-doped Bi2O3 NSs with a dimensionally stable anode (DSA) to realize battery-driven highly active CO2RR and OER with decent activity and efficiency.