Preparation And Chracterization Of BiVO₄ Composites And Its Photocatalytic Performance

Nowadys, Environmental pollution and energy shortage have become the obstacles of the continual development of human being. Photocatalytic technology has been considered to be a promising technology because of its application in the environment pollution purification and clean energy production. Bismuth vanadate as a photocatalyst, it has very strong light response in the visible light region and has a very good photocatalytic performance. However, the defects of small specific surface area and low separation efficiency in electron hole pair for bismuth vanadate limit its catalytic activity. In view of these defects, in this paper the researcher attempt to fabricate bismuth vanadate composites by coupling bismuth vanadate with some other semiconductor and expect to synthesize composite catalyst which have the stronger visible light response ability. In addition, it also expect to obtain the ability of generating hydrogen by splitting water. The main research contents and conclusions exhibit as follows:Novel Sn O2/Bi VO4 and In2O3/Bi VO4 heterojunction composite photocatalysts with various mole ratios have been prepared via a simple hydrothermal method, Ti O2/Bi VO4 heterojunction composite photocatalysts with various mole ratios have been prepared via a hydrothermal method coupled with microemulsion method. The structure, composition and optical properties of these composites were determined by X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), Raman spectroscopy, X-ray photoelectron spectroscopy(XPS) and UV-vis diffuse reflectance spectroscopy(UV-vis DRS), Brunauer-Emmett-Teller(BET) surface analysis, fourier transform infrared spectroscopy(FT-IR).Photocatalytic activities of the Sn O2/Bi VO4 and In2O3/Bi VO4 composites were evaluated by studying the degradation of methylene blue(MB) solutions under simulated visible light irradiation. Based on the characterization results and band structure of composite materials, the photocatalytic mechanism of composite materials was discussed preliminarily. The results show that the mole ratio of composite has great influence on the performance of catalyst, and there is exists an optimal mole ratio for Sn O2/Bi VO4 and In2O3/Bi VO4 composites. The 3:7 mole ratio Sn O2/Bi VO4 composite exhibited the highest photocatalytic performance, while the 5:5 mole ratio In2O3/Bi VO4 composite obtained the highest photocatalytic performance. Photocatalytic activities of the Ti O2/Bi VO4 composites were evaluated by studying the ability of generating hydrogen under simulated visible light and ultraviolet ligh irradiation. Based on the characterization results and band structure of composite materials, the photocatalytic mechanism of composite materials was discussed preliminarily. The results show that the pure Bi VO4 can’t generate hydrogen under both the visible condition and ultraviolet light condition, while the as-prepared Ti O2/Bi VO4 compositest have good hydrogen production performance. Under the condition of ultraviolet light, the prepared 30-BVO composite sample obtain higher hydrogen production efficiency than that of P25. Under the condition of visible light, the prepared pure Ti O2 sample can’t generate hydrogen, while the prepared Ti O2/Bi VO4 composites has good performance for hydrogen production. Furthermore, when the bismuth titanium mole percentage reachs 90 %, the 90-BVO samples has the best hydrogen production efficiency.