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Preparation, Characterization and Photocatalytic Property of Metal Doped TiO2 and Bi2WO6

Author: ZhangGuoQiang
Tutor: XuXiaoHong
School: Shandong University
Course: Applied Chemistry
Keywords: Photocatalytic Al doping Fe-doped TiO2 Bi2WO6
CLC: O643.36
Type: Master's thesis
Year: 2010
Downloads: 390
Quote: 0
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Abstract


Since 1972, Japanese scientists Fujishima and Honda discovered Ti02 single crystal electrodes can achieve the photocatalytic decomposition of water, semiconductor photocatalytic reaction has been strongly attracted to the research interests of the people. Among various oxide semiconductor photocatalysts, TiO2, because of its biological and chemical inertness, strong oxidizing ability, non-toxic and long-term stability of the anti-photochemical corrosion has been widely studied. However, from using sunlight efficiency of TiO2 exist main defects of the two aspects: on the one hand because of the TiO2 and a wide band gap (E = 3.2 eV), resulting in lower proportion of its light absorption wavelength range is narrow, utilization of solar energy; the other hand, TiO2 photo-generated carriers recombination rate is higher, resulting in lower quantum efficiency. To solve these problems, the development from the semiconductor Photocatalysis two fronts: (1) Modification Technology to improve the efficiency of TiO2 on the utilization of sunlight; (2) the development of a new type of semiconductor photocatalysts with visible light response. On this basis, the paper mainly studied metal ion doping Preparation and photocatalytic properties of titanium dioxide and tungsten bismuth nanomaterials characterization. Its main contents include: Preparation of Al-doped TiO2 nanomaterials by chemical solution decomposition and its acidification. Al-doped TiO2 nanomaterials crystalline structure, morphology and photophysical properties were characterized by XRD, TEM and UV-Vis technical means. XRD results indicate that not doped aluminum sample was heat-treated at 550 ℃ 2 h obtained is a mixture of rutile and anatase phase, but the sample obtained in the incorporation of aluminum, after the same heat treatment conditions it is pure anatase phase. Observed by TEM and found that compared with the non-doped aluminum sample, the smaller the particle size of the sample in the aluminum-doped, about 25 nm. The experimental characterization of photocatalytic degradation of methyl orange photocatalytic properties of the sample. The results show that: the Al-doped TiO2 samples better photocatalytic activity, and, after acidification, the doped aluminum sample photocatalytic activity can be further improved. The preliminary study that acidification treatment to remove part of the aluminum oxide nanoparticles in the aluminum-doped samples, so that the ratio of surface area of ??the sample caused by an increase of the improvement of the photocatalytic activity of the Al-doped TiO2 samples. The chemical solution decomposition prepared Fe-doped TiO2 nanomaterials and its acidification. XRD results showed that the Fe-doped TiO2 samples annealed at 500 ℃ is rutile and Fe2TiO5 of mixture. At 600 ℃ is of rutile, Fe2TiO5 and Fe2O3 mixture. And with increasing heat treatment temperature, a better crystallinity of the sample. UV-visible diffuse reflectance spectra of 500 ℃ and 600 ℃ for Fe-doped TiO2 samples with the absorption of visible light response. 500 ℃ for Fe-doped TiO2 samples compared to samples in the absorption of the heat treatment of 600 ° C with obvious redshift. Photocatalytic Degradation of Rhodamine B photocatalytic properties of the material was characterized. The results show that: Fe-doped TiO2 samples with visible light photocatalytic activity of rhodamine B, acidification treatment has little effect on the photocatalytic activity of the iron-doped samples. The chemical solution decomposition the prepared layered perovskite structure oxide Bi2WO6 photocatalyst and its acidification. The XRD results show that the composition of a sample prepared by the heat treatment of 700 ° C C the main product (Bi2WO6) and byproducts (Bi14W2O27) two substances. The annealed sample after acidification Bi14W2O27 the diffraction peaks completely disappear and the pure phase Bi2WO6 samples were obtained. The acidified sample supernatant detected by ICP analysis, the mechanism of purely phase Bi2WO6 sample obtained most likely to be acidified processing selection bismuth oxide the Bi14W2O27 structure is filtered off, so that the Bi14W2O27 complete conversion Bi2WO6. The SEM images show that the morphology of the sample at a the acidification treatment temperature of 70 ° C, the obtained sheet-like structure of the nano-size. UV-visible diffuse reflectance spectra of acidified samples with the absorption of visible light response. Rhodamine B photocatalytic degradation experiments found that the acidification treatment can improve the Bi2WO6 the photocatalytic activity, but the nanoparticles obtained at 70 ° C acidified a flaky Bi2WO6 sample light highest catalytic activity.

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic > Catalyst
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