Hydrothermal Synthesis and Visible-light Photocatalytic Properties of BiVO4 with Different Structures and Morphologies

Visible-light photocatalysts BiVO4 with different crystal structures and morphologies were prepared via a mild additive-free hydrothermal method. The as-prepared samples were well-determined by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-Vis diffuse reflectance spectroscope (DRS) and low-temperature N-2 adsorption. The results indicated that both hydrothermal temperature and pH value of reaction solution had significant influence on the formation of crystal structures. Hydrothermal temperature of 180 C and acidic condition facilitated the formation of monoclinic BiVO4. The pH value of reaction solution also affected the morphologies of samples remarkably, which resulted in three different types: sheet-, cube- and rod-like shapes. All the samples were applied to the photodegradation of methylene blue (MB) under visible light and sheet-like BiVO4 obtained in pH=2 reaction solution exhibited the best photocatalytic activity (4 h, 92.0%). In addition, influence factors of this photocatalytic system were thoroughly investigated, which included photocatalyst dosage, initial concentration and the existence of electron acceptors. The optimal photocatalytic condition was as follow: the dosage of catalyst was 1.0 g/L, the initial concentration of methylene blue was 10 mg/L, and KBrO3 was used as electron acceptor.