Effect of Bismuth (Bi) concentration on Bi/Sn electrodes prepared by electrodeposition in electrochemical reduction of CO2 to toward solid carbon products

Abstract

Carbon dioxide (CO2) is the main greenhouse gas that contributes to climate change. The electrochemical carbon dioxide reduction (CO2RR) is an interesting and low-cost CO2 conversion technology using renewable electricity as an energy source. Herein, CO2RR to solid carbon products was studied on bismuth/tin (Bi/Sn) electrodes synthesized by electrodeposition method. Different Bi concentration (0.01 M,0.03 M, 0.05 M,0.07 M and 0.1 M) were used to prepare the electrodes by electrodeposition method. The SEM-EDX and EIS results which reveal that the Bi/Sn electrode prepared in 0.05 M Bi 3+ had the lowest charge transfer resistance and was indicated as a CO2RR promising effective electrocatalyst. The catalytic performances of the electrodes in CO2RR were exanimated under an electrolyte system containing [BMIM]BF4/propylene carbonate/water at the applied potential between -1.1 to -1.7 V vs. Ag/AgCl to produce carbon products. Raman spectroscopy, NMR, and GC were used to analyze the solid, liquid, and gaseous products, respectively. From TEM results, the solid carbon products were identified as polycrystalline graphene. The proper bismuth structures and suitable reaction conditions for CO2RR to solid carbon products on the Bi/Sn electrocatalysts were obtained at 0.05 M Bi3+ and -1.3 V vs. Ag/AgCl, respectively.