Tunable selectivity on copper–bismuth bimetallic aerogels for electrochemical CO2 reduction

Electrochemical carbon dioxide (CO2) reduction has been studied on a series of copper–bismuth (CuBi) bimetallic catalysts; however, most of the reported CuBi catalysts tend to exhibit high selectivity towards formate. Here we design four bimetallic CuxBi aerogel electrocatalysts with adjustable composition, which exhibit tunable selectivity for CO2 reduction. The maximum Faradaic efficiency (FE) of CO (86.6%) and formate (60.8%) over Cu100Bi and Cu5Bi is 1.2 and 5.5 times higher than that over the Cu catalyst, respectively. While for Cu50Bi, it shows enhanced selectivity for CH4 (FE=26.0%). The C2H4 FE of Cu10Bi (31.6%) is 1.6 times higher than that of the Cu catalyst. X-ray photoelectron spectroscopy analysis reveals that introduction of different amounts of Bi element leads the variation of Cu(II)/Cu(I) ratios on the catalysts surface, thereby regulating the hydrogenation capability of the reaction intermediates during CO2 reduction.