High-efficient carbon dioxide-to-formic acid conversion on bimetallic PbIn alloy catalysts with tuned composition and morphology

CO 2 electroreduction to value-added chemicals and fuels has gained increasing attention; however, there are only a few catalysts with high performance under mild conditions that can be used in this technique. In this study, single metal Pb, In and bimetallic PbIn catalysts for aqueous CO 2 electroreduction were prepared using a facile 3-step process including PbIn granulation by reducing Pb(NO 3 ) 2 /In(NO 3 ) 3 aqueous solution with NaBH 4 , calcination in air, and in situ electroreduction. The bimetallic PbIn catalysts had better catalytic performance on CO 2 electroreduction than single metal catalysts. The bimetallic Pb 7 In 3 catalyst (atomic ratios of Pb and In is 7:3) presented the highest formic acid faradaic efficiency of 91.6% at −1.26 V vs reversible hydrogen electrode in a 0.5 M CO 2 -saturated KHCO 3 aqueous solution, which was 13% and 9.7% higher than that of single Pb and In catalysts, respectively. Moreover, the catalyst remained active after 10 h of continuous CO 2 electrolysis with a stale current density of −17 mA cm −2 . The experimental results showed that the excellent catalytic performance of Pb 7 In 3 catalyst may stem from its higher electrochemical active surface area, lower charge-transfer resistance and the synergistic effect of Pb and In in the catalyst. The presented bimetallic PbIn catalysts may have a wide of application prospect, and they may be synthesized from heavy metals in industrial wastewaters .