Self-assembled BiVO4/Bi2WO6 microspheres: synthesis, photoinduced charge transfer properties and photocatalytic activities

Three-dimensional (3D) BiVO4/Bi2WO6 composite microspheres with enhanced visible-light (λ > 420 nm) photodegradation activity of methylene blue (MB) were synthesized by a simple, one-pot, template-free solvothermal method. A mixture of ethylene glycol (EG) and H2O (volume ratio of EG-H2O was 1 : 1) was used as the solvent. To investigate the relationship between structure and photocatalytic performance, the as-synthesized samples were characterized by XRD, FESEM, HRTEM, UV-vis DRS, SPS and TPV. Structural characterizations indicated that the composite nanostructure mainly consisted of two single-crystal phases, which were BiVO4 and Bi2WO6. In addition, a possible growth mechanism of this microsphere composite and the separation process of photoinduced charge carriers in the heterojunction are discussed.