Improved Performance of BiVO4 via Surface-Deposited Magnetic CuFe2O4 for Phenol Oxidation and O2 Reduction and Evolution under Visible Light.

Monoclinic BiVO4 (BiV) is a good photoanode for water oxidation but a poor photocatalyst for organic oxidation because of slow O2 reduction. In this work, a well-crystallized BiV microdecahedron (1-2 µm) has been deposited with a poorly crystallized cubic CuFe2O4 (CF) nanosphere (100 nm). For phenol oxidation and O2 reduction to H2O2 in aqueous suspension under visible light, 1 wt % CF/BiV was more active than BiV by approximately factors of 14 and 7, respectively, while CF was almost not active. A (photo)electrochemical measurement showed that CF/BiV was more active than BiV not only for phenol and water oxidation under visible light but also for O2 reduction and water oxidation in the dark. Moreover, as compared to BiV, CF/BiV was more efficient in the charge transfer to a solution species but less efficient either in the light-on electron generation or in the light-off electron disappearance. Based on the solid band edge potentials measured by ultraviolet photoelectron spectroscopy, a possible Z scheme mechanism is proposed involving charge recombination at the CF/BiV interfaces followed by the increased O2 reduction on CF and the increased phenol oxidation on BiV.