Substitution of Ce(III,IV) ions for Bi in BiVO4 and its enhanced impact on visible light-driven photocatalytic activities

Abstract

Bi_1−xCe_xVO_4+δ (0 ≤ x ≤ 0.3) solid solution photocatalysts were synthesized by substitution of Ce for Bi in the BiVO₄ lattice using the hydrothermal method. X-ray diffraction, Raman spectroscopy and high-resolution transmission electron microscopy revealed that the crystal phase transformed from the monoclinic phase to the tetragonal phase, probably due to the substitution of cerium ions in the Bi³⁺ positions. UV-vis diffuse reflectance spectroscopy was used to investigate the absorption range and band gap of the photocatalysts. The photocatalytic activities of the prepared samples were examined by studying the degradation of MB and phenol under visible-light irradiation and the best performance was attained for the sample with a cerium content of 20 at% (Bi_0.8Ce_0.2VO_4+δ). The results of photoluminescence spectroscopy and photocurrent measurement demonstrated that the recombination of photogenerated charges was greatly depressed and the photocatalytic activity was improved by the substitution of Ce for Bi in BiVO₄. Furthermore, the proposed mechanism of the enhanced photocatalytic activity was discussed.