Selective electrooxidation glycerol to lactic acid coupled with hydrogen production over a cooperative BiOx/Au catalyst

Utilizing sustainable electrocatalysis to upcycle glycerol (GLY; the by-product of biodiesel) to lactic acid (LA; the key monomers for biodegradable polymer) is an efficient way to reduce the cost of biodiesel, which is also consistent with the waste-to-wealth principle. However, current research still suffers from issues of low LA selectivity (<80%), especially at high current density. Herein, we designed a cooperative catalyst by modifying BiOx nanolayers on gold nanoparticles (BiOx/Au), achieving high LA selectivity (82%) at high current density (226 mA cm(-2) at 1.05 V vs. RHE), outperforming most of the reported works in the literature. We reveal that BiOx could promote the adsorption of the middle hydroxyl of GLY, which facilitates the formation of DHA and thus enables high LA selectivity. Moreover, the electron-deficient Au in BiOx/Au is responsible for the enhanced current density, which is more beneficial to generate reactive oxygen species (OH*). To further reveal the application potential of this electrocatalytic strategy, we realized that the conversion of crude GLY extracted from cooking oil to LA coupled with H-2 production using a membrane-free flow electrolyzer, demonstrating a sustainable fashion to convert biodiesel waste into high value-added product and H-2 fuel.