From Hollow Olive-Shaped BiVO4 to n-p Core-Shell BiVO4@Bi2O3 Microspheres: Controlled Synthesis and Enhanced Visible-Light-Responsive Photocatalytic Properties

In this study, hollow olive-shaped BiVO4 and n-p core-shell BiVO4@Bi2O3 microspheres were synthesized by a novel sodium bis(2-ethylhexyl)sulfosuccinate (AOT)-assisted mixed solvothermal route and a thermal solution of NaOH etching process under hydrothermal conditions for the first time, respectively. The as-obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy, Brunauer-Emmett-Teller surface area, and UV-vis diffuse-reflectance spectroscopy in detail. The influence of AOT and solvent ratios on the final products was studied. On the basis of SEM observations and XRD analyses of the samples synthesized at different reaction stages, the formation mechanism of hollow olive-shaped BiVO4 microspheres was proposed. The photocatalytic activities of hollow olive-shaped BiVO4 and core-shell BiVO4@Bi2O3 microspheres were evaluated on the degradation of rhodamine B under visible-light irradiation (lambda > 400 nm). The results indicated that core-shell BiVO4@Bi2O3 exhibited much higher photocatalytic activities than pure olive-shaped BiVO4. The mechanism of enhanced photocatalytic activity of core-shell BiVO4@Bi2O3 microspheres was discussed on the basis of the calculated energy band positions as well. The present study provides a new strategy to enhancing the photocatalytic activity of visible-light-responsive Bi-based photocatalysts by p-n heterojunction.