pH-Induced selective electrocatalytic hydrogenation of furfural on Cu electrodes

The efficient and selective electrocatalytic hydrogenation (ECH) of furfural is considered a green strategy for achieving biomass-derived high-value chemicals. Regulating an aqueous electrolytic environment, a green hydrogen energy source of water, is significant for improving the selectivity of products and reducing energy consumption. In this study, we systematically investigated the mechanism of pH dependence of product selectivity in the ECH of furfural on Cu electrodes. Under acidic conditions, the oxygen atom dissociated directly from hydrogenated furfural-derived alkoxyl intermediates, followed by stepwise hydrogenation until H2O formation via a thermodynamically favorable proton-coupled electron transfer process, thereby inducing a high proportion of the hydrogenolysis product (2-methylfuran). However, under partial alkaline conditions, furfural could be directly hydrogenated to furfuryl alcohol (selectivity ~98%) due to the high-energy barrier of the deoxidation process via a surface hydride (Had) transfer. Our results highlight the vital role of the electrolytic environment in furfural selective conversion and broaden our fundamental understanding of hydrodeoxygenation reactions in ECH.