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Preparation, Characterization and Properties of Pr2InNdO7、MoO3/TiO2and Bi2S3/BiOBr Photocatalysts

Author: ZuoQingFeng
Tutor: CuiYuMin
School: Anhui University
Course: Physical and chemical
Keywords: Pr2InNdO7 MoO3/TiO2 Bi2S3/BiOBr Photocatalysis Methyl orange Methylene blue
CLC: TQ426
Type: Master's thesis
Year: 2014
Downloads: 2
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Due to the excessive exploitation and utilization of natural resources, our living environment has been damaged greatly. Environmental problem has become a major issue in the world. Nowadays, as a kind of "green" technology, photocatalytic technology can be used to dealed with environmental pollution problem. Photocatalytic technology has a very wide range of application values, and because of its benefits, it has been got a great deal of attention by many researchers. Photocatalytic technology has gradually become one of the hotspots of researchers study. Up to now, TiO2, ZnO, WO3and other metal oxides, these photocatalytic materials have been developed and applied. Generally speaking, these photocatalytic materials have the advantages of low cost, high chemical stability, higher UV photocatalytic efficiency and so on. However, the usefulness of these photocatalytic materials is limited to ultraviolet light, lower solar energy conversion efficiency, higher recombination of electron-hole pairs, which restricts its photocatalytic efficiency enhancement. Therefore, how to use appropriate method to modify photocatalytic materials, narrow light absorption spectra to improve the photocatalytic efficiency, which become the main research direction of photocatalyst.In this work, we used solid phase reaction, impregnation-calcination and hydrothermal method to synthesize Pr2InNd07, MoO3/TiO2and Bi2S3/BiOBr photocatalysts. And We used a series of modern techniques to characterize the photocatalysts. We studied the relation between the structure and photocatalytic performance of photocatalysts. As follows:our researching work divided three sections.First, Pr2InNdO7photocatalysts were prepared by solid phase reaction method at873K and characterized by means of X-ray diffraction (XRD)> UV visible diffuse reflection spectroscopy (UV-Vis DRS)、. Brunauer-Emmett-Teller (BET) and photoluminescence (PL) spectra. The activities of Pr2InNdO7photocatalysts were evaluated by using methylene blue (MB) as a mode compound of photocatalytic reaction under UV and visible light irradiation. The results show that Pr/In/Nd ratios have an important effect on the photocatalytic activities of Pr2InNdO7photocatalysts. When Pr/In/Nd ratio is1:4:1, the photocatalytic activities of Pr2InNdO7photocatalysts reach the maximums under UV and visible light irradiation, respectively, and its photocatalytic activities are obviously higher than those of pure In2O3. The remarkably enhanced photocatalytic activities can be mainly attributed to the fact that an appropriate amount of Nd2O5and Pr2O3combined with In2O3increase its BET surface area, improve the separation efficiency of photogenerated electrons and holes, and heighten the absorption intensity in200-800nm light region.Second, Using an aqueous solution of (NH4)6Mo7O24·4H2O and commercial anatase TiO2as precursors, MoO3/TiO2composite photocatalysts with different mass ratios of MoO3and TiO2were prepared by an impregnation-calcination method. The obtained samples were characterized by X-ray diffraction (XRD), UV-visible diffuse reflectance (UV-Vis DRS) and high-resolution transmission electron microscopy (HRTEM). The UV light photocatalytic activity of H2evolution on MoO3/TiO2composite photocatalysts was evaluated. Furthermore, the UV light photocatalytic activity of MoO3TiO2was evaluated by using methyl orange (MO) as model compounds. The active species in the photocatalytic reaction process of MO were studied by adding various radical scavengers. The results have shown that compared with pure TiO2and MoO3,20%MoO3/TiO2photocatalyst in the400-700nm region, the absorption band edge moves to longer wavelengths and has a stronger optical absorption property and. In all MoO3/TiO2samples,20%MoO3/TiO2photocatalyst has the highest UV light photocatalytic activity. h+,籓H, H2O2and·O2", especially h+together dominated the photocatalytic degradation process of methyl orange.Third, Bi2S3/BiOBr nanocomposites with various weight percents of Bi2S3were successfully prepared by a facile hydro thermal process at433K, and characterized by a series of modern techniques. The activities of the as-prepared Bi2S3/BiOBr samples were evaluated by using methyl orange (MO) as a mode compound of photocatalytic reaction under UV and visible light irradiation. The results indicated that the photocatalytic activity of the Bi2S3/BiOBr samples was greatly increased, compared with that over the pure BiOBr and Bi2S3. The enhanced photocatalytic activities could be mainly owing to the effective transfer of the photogenerated electrons and holes at the heterojunction interface of BiOBr and Bi2S3, which maked the recombination of electron-hole pairs decrease, and the mechanism of photocatalytic activity increasement was discussed.

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