The Fabrication Of Visible-light Responsed Bismuth Vanadate And Composition And The Study Of Their Photocatalytic Performance

With our environment becoming worse and worse, especially water pollution, the most important thing for people is to find an effective way to deal with environment pollution. The photocatalytic degradation of organic pollution in water, nowadays, has been considered as an ideal method to treat environment pollution. TiO2, an excellent photocatalyst, can only be responded under ultraviolet light and its photoinduced hole-electron pairs can rapidly recombine, which inhabits its potential application. As a new kind of photocatalyst, BiVO₄ can be responded under visible light. For BiVO₄, however, there is the same problem, namely the heavy recombination of hole-electron pairs. Thus, the principal line in this paper is to separate the hole-electron pairs effectively so as to improve the performance of Bi VO4. Also, the relationship between morphology and performance was investigated in this paper.This thesis is elaborated from the follow aspect:（1） The crystal structure and different morphologies of monoclinic scheelite-type BiVO₄ were studied. The crystal structure of monoclinic scheelite-type BiVO₄ was discussed via diamond software. Monoclinic scheelite-type BiVO₄ with different morphologies were synthesized by various methods and their performance was discussed. The results demonstrated that the sheet-like BiVO₄ possessed the best photocatalytic performance. Under light irradiation for 3 h, the degradation degree of RhB was about 50%. The high performance was due to the exposed high-activity crystalline plane of（040） and the short transfer path of hole-electron pairs.（2） The BiVO₄/Bi₂O₃ composition photocatalysts with different ratios of Bi and V were prepared by the hydrothermal method. During the preparation, the Bi/V ratio can be simply controlled by changing the content of bismuth nitrate. The result demonstrated that the performance depended on the ratios of Bi and V. The performance of the composition improves with the increasing of Bi/V. Among these samples, the composition with the Bi/V ratios of 1.3 showed the highest photocatalytic property: 90% of RhB was removed under 3 h reaction, and the degradation rate was 3 times higher than that of BiVO₄. However, the performance decreased with increasing of Bi/V continuely, which was due to the excess of Bi₂O₃ coating on the BiVO₄.（3） The photocatalytic performance of BiVO₄/rGO was studied. RGO is a kind of two-dimensional material, which exhabits low resistance and high electron migration. Thus, the combination of electrons and holes could be effectively inhibited when the rGO was connected with BiVO₄, which improved the photocatalytic efficient. In this experiment, BiVO₄/rGO was synthesized under UV light. The results proved that the photocatalytic property of BiVO₄/rGO was 4 times higher than that of BiVO₄. The photoinduced electrons can be rapidly transferred through rGO, so the recombination of electrons and holes can be effectively inhabited.（4） The high property BiVO₄/Cu2 O photocatalyst was synthesized by a simple and efficient process. First, the sheet-like BiVO₄ was prepared by hydrothermal; then the Cu2 O nanoparticles grew on the surface of BiVO₄. The p-n junction was formed when these two semiconductors combined together. The performance depends on the ratios of BiVO₄ and Cu2 O. The performance of the composition improves with the increasing of Cu2 O.When the weight fraction of Cu2 O reaches to 15%, the composition showed the best photocatalytic performance. After 2 h irradiation, the RhB could be entirely removed. However, the performance decreased with increasing of Cu2 O continuely, which was due to the excess of Cu2 O coating on the BiVO₄ and the excess of Cu2 O decreased the performance of BiVO₄. The p-n junction is advantage for the separation of electron-hole, so that the photocatalytic performance of BiVO₄/Cu2 O can be increased.