Improved Performance\nof BiVO₄ via Surface-Deposited\nMagnetic CuFe₂O₄ for Phenol Oxidation and O₂ Reduction and Evolution under Visible Light

Abstract

Monoclinic BiVO₄ (BiV) is a good photoanode\nfor water\noxidation but a poor photocatalyst for organic oxidation because of\nslow O₂ reduction. In this work, a well-crystallized BiV\nmicrodecahedron (1–2 μm) has been deposited with a poorly\ncrystallized cubic CuFe₂O₄ (CF) nanosphere (100\nnm). For phenol oxidation and O₂ reduction to H₂O₂ in aqueous suspension under visible light, 1 wt % CF/BiV\nwas more active than BiV by approximately factors of 14 and 7, respectively,\nwhile CF was almost not active. A (photo)­electrochemical measurement\nshowed that CF/BiV was more active than BiV not only for phenol and\nwater oxidation under visible light but also for O₂ reduction\nand water oxidation in the dark. Moreover, as compared to BiV, CF/BiV\nwas more efficient in the charge transfer to a solution species but\nless efficient either in the light-on electron generation or in the\nlight-off electron disappearance. Based on the solid band edge potentials\nmeasured by ultraviolet photoelectron spectroscopy, a possible <i>Z</i> scheme mechanism is proposed involving charge recombination\nat the CF/BiV interfaces followed by the increased O₂ reduction\non CF and the increased phenol oxidation on BiV.