Ultrafast Electron Transfer at BiVO4-VOx Z-Scheme Interface for Enhanced Selective Oxidation of Glycerol to Dihydroxyacetone.

Photoelectrochemical (PEC) selective oxidation of glycerol offers a sustainable strategy to obtain dihydroxyacetone (DHA) as a value-added chemical, which remains challenging owing to the slow kinetics and low selectivity. We construct a Z-scheme heterojunction consisting of an amorphous vanadium oxide nanolayer on BiVO4 nanoparticles (BiVO4-VOx) for glycerol oxidation by a spatially confined photoelectron deposition method. BiVO4-VOx photoanode achieves a high DHA evolution rate of 400.4 mmol m-2 h-1 and a selectivity of 65.6% at 1.2 V vs. RHE. Femtosecond transient absorption spectroscopy analysis demonstrates superior charge separation efficiency and ultrafast interfacial transfer kinetics, enabling long-lived photogenerated electrons and holes accumulated in BiVO4 conduction band and VOx valence band, respectively. Furthermore, in situ Fourier transform infrared spectroscopy and theoretical calculations reveal that the synergy between the optimized electronic structure of amorphous VOx and Z-scheme heterojunction promotes preferential adsorption of glycerol middle hydroxyl groups and lowers the energy barrier of the rate-determining step, thus facilitating selective DHA production. We fabricated a self-powered device with a DHA productivity of 122.0 mmol m-2 h-1, a H2 productivity of 1.33 mL cm-2 h-1 and a solar-to-H2 conversion efficiency of 4.7%. This work highlights the potential of heterojunction engineering for PEC biomass valorization toward value-added products.