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

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.