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

CO2 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 CO2 electroreduction were prepared using a facile 3-step process including PbIn granulation by reducing Pb(NO3)2/In(NO3)3 aqueous solution with NaBH4, calcination in air, and in situ electroreduction. The bimetallic PbIn catalysts had better catalytic performance on CO2 electroreduction than single metal catalysts. The bimetallic Pb7In3 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 CO2-saturated KHCO3 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 CO2 electrolysis with a stale current density of -17 mA cm-2. The experimental results showed that the excellent catalytic performance of Pb7In3 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.