The formation mechanism of a Er3+-doped heterojunction ms/tz-BiVO4 with enhanced photocatalytic performance under visible light

BiVO4 products doped with different proportions of erbium were prepared by a hydrothermal reaction with varied reaction time. X-ray diffraction reveals the phase transformation from the tetragonal zircon BiVO4 to the monoclinic scheelite phases with increasing reaction time even without Er3+ doping. Scanning electron microscopy shows that the morphology of the samples transforms from an irregular structure to rod-like shapes accompanied with the crystalline phase transformation. UV-vis diffuse reflectance spectra and transmission electron microscope indicate that a core-shell structure may form in the meantime. Photocatalytic performance tests have been performed and the mechanism of the improved photocatalytic performance is discussed. In the end, the formation mechanism of the core-shell structure samples and effect of the Er3+ in the crystalline phase transformation are further discussed.