Microstructure and photocatalytic performance of BiVO4 prepared by hydrothermal method

Monoclinic BiVO₄ photocatalyst was hydrothermally synthesized at different pH conditions without surfactant. The microstructure and photocatalytic behavior of as‒prepared samples were characterized by X−ray diffraction, scanning electron microscope, transmission electron microscopy, UV–vis diffuse reflectance spectra, electrochemical workstation and dye degradation experiment. The results show that the pH value had a significant influence on the microstructure and photocatalytic performance of BiVO₄. In acid environment, heavy precipitation of tetragonal BiVO₄ took place in a short time at room temperature, whereas only amorphous powders formed as the pH value was equal or higher than 7. The monoclinic BiVO₄ gradually nucleated and grew at the early stage of synthesis procedure at 180 °C, and finally became the unique crystalline phase. The relationship between microstructure and photocatalytic activity the photocatalyst was well discussed. It is observed that the BiVO₄ prepared in the neutral condition (pH 7) exhibited desirable photocatalytic degradation efficiency toward Rhodamine B solution, mainly due to the efficient separation of photogenerated electron‒hole pairs and enhanced visual light absorption during degradation process, which were ascribed to the comprehensive function of high exposed {010} crystal facets, close packed structure, small particle size, and special floating characteristic.