Benefits on photocarrier transfer from transition of 3D to 2D morphology
The severe photogenerated carriers recombination of BiVO4 leads to poor performance and limits extensive commercial application. Here, the BiVO4 nanocrystalline powder and the epitaxial BiVO4 films were prepared by using hydrothermal method and laser pulse deposition, respectively. The BiVO4 powder had the typical morphology of truncated tetragonal bipyramid, whereas the epitaxial BiVO4 film was composed of nano-islands uniformly distributed on (001)-oriented yttrium stabilized zirconia (YSZ) substrate. Compared with the three-dimensional (3D) nanocrystalline powder, the nano-islands are much more approximate to two-dimensional (2D) morphology. According to the results of rhodamine B degradation experiments under 440 nm monochromatic light irradiation, the apparent quantum yield was increased by 1.75 times with the morphology transformation from 3D to 2D. The epitaxial BiVO4 films had more negative conduction band position and exposed larger ratio of (010) facets, which were beneficial to the utilization of photogenerated electrons. In addition, the higher oxygen vacancy content of BiVO4 films was also conductive to the separation of photogenerated carriers. The synergistic effect of 2D morphology and oxygen vacancies promotes the photocatalytic activity of epitaxial BiVO4 films.