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 selec-tivity 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.