Facile one-pot synthesis and photocatalytic properties of hierarchically structural BiVO4 with different morphologies

Hierarchically structured m-BiVO4 crystals with twin-ball-like, cauliflower-like, pinwheel-like, columnar and spherical morphologies were synthesized by a facile one-pot method in the presence of soluble starch. The physicochemical properties of the material were characterized by means of XRD, SEM, HRTEM/SAED, UV-vis absorption and N-2 adsorption techniques. The oriented aggregation mechanism may rationally explain the formation of the hierarchical structure. The assistance of the starch and the pH value of the precursor solution play pivotal roles in the formation of the hierarchical structures with different morphologies because the existing forms of bismuth and starch vary with the pH value of the precursor solution. The photocatalytic activities of the as-prepared BiVO4 samples were evaluated for the photodegradation of Rhodamine B (RhB) in aqueous solution under simulated sunlight irradiation. The highest photocatalytic activity of BiVO4 obtained at pH = 4 may result from several factors, such as the moderate BET surface area, the highest crystallinity, the lowest bandgap and the most exposed (040) face.