Synthesis of buckhorn-like BiVO4 with a shell of CeOx nanodots: Effect of heteroj unction structure on the enhancement of photocatalytic activity

Composite photocatalysts CeOx/BiVO4 with a heterojunction structure were synthesized using hydrothermal and ion-impregnation method. The composites were characterized by X-ray diffraction, BET, high-resolution transmission electron microscopy, selected area electron diffraction, and X-ray photoelectron spectroscopy. UV-vis diffuse reflectance spectroscopy was used to investigate the absorption range and band gap of photocatalysts. The photocatalytic activities of the prepared samples were also examined by studying the degradation of methylene blue under visible-light irradiation. Results showed that the composite with 5.7 wt.% CeOx/BiVO4 exhibited the highest photocatalytic activity within the studied range. The separation of the photogenerated charge and the effect of heterojunction structure on photocatalytic activities could be well interpreted based on the heterojunction structure with consideration of the Fermi level. The charge-separation process and the important role of deposited cerium were proven by photoluminescence spectroscopy and electron paramagnetiC resonance spectra. Results demonstrated that the heterojunction structure and the electron-trapping effect of cerium greatly depressed the recombination of photogenerated charges in the composites. (C) 2015 Elsevier B.V. All rights reserved.