Impact of Preparative pH on the Morphology and Photocatalytic Activity of BiVO_4

摘要

Adjusting pH with an ammonia solution during the synthesis, single-crystalline BiVO_4 has been prepared using Bi(NO_3)_3·5H_2O and NH_4VO_3 as starting materials through aqueous-phase precipitation at room temperature. The prepared samples are characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). The impact of pH on structure, surface morphology, visible-light photocatalytic activity, and light absorption performance of BiVO_4 is explored and discussed. During the synthesis process, neither extremely acidic (low pH) nor basic (high pH) conditions are desirable for the formation of BiVO_4 in monoclinic phase. The highest photocatalytic performance on the degradation of a methylene blue solution is observed under pH = 7.0 for BiVO_4 in monoclinic scheelite, which is attributed to its small grain size and marked surface oxygen evolution ability.