Electrochemical reduction of carbon dioxide to formate on Bi and BiSn electrodes prepared by electrodeposition on copper foil

Abstract

In this study, The Bix/Cu electrocatalysts were prepared by electrodeposition of Bi on Cu foil, and the BixSny/Cu electrocatalysts were prepared by electrodeposition of Bi and Sn on Cu foil in deposition solution bath with different Bi3+ ion concentrations of 0.05, 0.1, and 0.2 M (Bi0.05/Cu, Bi0.1/Cu, Bi0.2/Cu), while the Sn2+ ion concentration was constant at 0.025 M (Bi0.05Sn0.025/Cu, Bi0.1Sn0.025/Cu, Bi0.2Sn0.025/Cu). The electrocatalysts were characterized by SEM-EDX, XRD, and XPS and tested in the electrochemical CO2 reduction reaction. The results demonstrate that the Bi concentrations in the deposition bath affect the structure of Bi into different forms, including bulky structure and rough surface. Under the electrochemical CO2 reduction reaction experiments, H2 and CO were detected in the gas products, while formate was a major liquid product as confirmed by NMR analysis. The Bi0.1/Cu electrocatalyst gives the best catalytic performance for formate formation at a potential of -1.8 V vs. Ag/AgCl with a high formate production rate of 5.41 µmol/min.cm2. In addition, the Bi0.1/Cu electrocatalyst was highly stable with FE formate above 80% for 10 hours, although the Bi bulky particles had slightly changed after reaction due to the formation of Bi2O2CO3 species.