High-active CoPi-Ov nanolayer promotes photoelectrochemical glycerol oxidation for efficient dihydroxyacetone production

The increasing global consumption of biofuels calls for efficient transformation of the main by-product glycerol (GLY) in the biodiesel and bioethanol industry process. Photoelectrochemical (PEC) oxidation of GLY to high value-added C3 products like preferred dihydroxyacetone (DHA) over a BiVO4 photoanode remains challenging, due to the low photocurrent density and/or selectivity and thus insufficient DHA productivity (<400 mmol m−2 h−1). Herein, we report the PEC GLY oxidation to DHA over a heterogeneous photoanode of the cobalt phosphate nanolayer with rich oxygen vacancies (Ov) anchored on BiVO4 (CoPi-Ov/BiVO4). The conversion achieves the highest DHA production rate of 454.9 mmol m−2 h−1 among reported BiVO4-based photoanode to date. We demonstrate that the CoPi-Ov nanolayer is featured with amorphous morphology and enriched Ov facilitating photo-induced charge separation and hole transport, thereby providing more active sites for GLY oxidation reaction (GOR). TR-FTIR, radical recognition assays and DFT calculations verify that the Co atoms in CoPi-Ov preferentially interact with the middle hydroxyl of GLY to form carbon-centered radicals, promoting the oriented production and desorption of DHA. This study highlights a GOR system, starting from facile photoanode synthesis to the design of high-active photoelectrocatalyst enlightened by structure-activity relationship, which potentiates biomass valorization to generate valuable products.