A thermo-electroreduction strategy unlocks propylene glycol synthesis from glycerol at ampere level current density

The production of valuable chemicals from glycerol can alleviate its large market surplus and reduce emissions that arise from petrochemical-based feedstocks. Here we show that a thermo-electroreduction strategy can expand the scope of glycerol valorization to a product of higher effective H/C ratio, such as propylene glycol. The thermal dehydration of glycerol unlocks the hydroxyacetone intermediate, which can undergo subsequent electrocatalytic hydrogenation to propylene glycol using Co-cluster-decorated Cu foam electrocatalyst. Theoretical simulations suggest that Co/Cu modulates the adsorption configuration of hydroxyacetone, such that all functional groups are in similar distance from the surrounding water layer and the surface. This can facilitate low-energy-barrier hydrogenation of the O atom on hydroxyacetone by solvated H species through an Eley-Rideal-type mechanism, followed by spontaneous hydrogenation of the adjacent C atom. We thus achieve high Faradaic efficiencies towards propylene glycol of ~81% even at current densities up to 1000 mA/cm².