Effects of structural variation on the photocatalytic performance of hydrothermally synthesized BiVO4

Highly crystalline monoclinic scheelite BiVO4 powders are synthesized from aqueous Bi(NO3)(3) and NH4VO3 solutions over a wide range of pH by a hydrothermal process. BiVO4 powders with various morphologies , surface textures and grain shapes are selectively synthesized by adjusting the pH. The dependence of the Ramen peak position and intensity on the synthesis conditions indicates that the symmetry disortions in the local structure of the synthesized BiVO4 are affected by the preperation conditions. These variations in the local structure result in the modification of the electronic structure of BiVO4, which results in a blue-shift in the UV-vis absorption spectrum of hypothermally synthesized BiVO4 in comparison with a well-crystallized sample prepared by homogeneous coprecipation. The photocatalytic for O-2 evolution from an aqueous AgNO3 solution under visible light irradiation are stronglt dependent on the pH used in the synthesis. The differences in the photocatalytic activities between BiVO4 samples prepared under various conditions is attributed to the the degree of structural distortion, leading to differences in the mobility of photogenerated holes formed in the valence band, which consists of Bi 6s and O 2p orbitals.