| As a facile and high-efficiency approach for synthesis of nanomaterials, electrospinning is widely used to prepare nanostructures materials such as nanofibers, nanotubes, nanobelts. As a semiconductor photocatalyst, Titanium dioxide (TiO2) is used in managing environmental issues, development and utilization of new energy sources. TiO2-based composite nanomaterials prepared by electrospinning were widely applied to environmental and energy fields arising from their excellent properties. In this thesis, the electrospun TiO2nanofibers and nanotubes were composited with NiO and graphene to obtain nanocomposite photocatalysts, respectively. The TiO2-based composite photocatalysts are investigated to degrade rhodamine B (RhB) under UV and visible light irradiation, respectively. The mechanism of prepared composite photocatalysts was discussed. The main content of this thesis is as the following:1. TiO2nanofibers and nanotubes were prepared by electrospinning and their photocatalytic properties are investigated. TiO2nanofibers were obtained by using precursor solution, which is consisted of tetrabutyl titanate as titanium source, polyvinyl pyrrolidone as agglomerant, ethanol and N, N-dimethyl formamide as solvent. TiO2nanotubes were obtained by using oil added precursor solution of TiO2nanofibers at high temperature. Electrospun TiO2nanofibers with smoothing surface and large aspect ratio area are uniform. While, porous TiO2nanotubes are composed of TiO2nanoparticles. The electrospun T1O2nanomaterials with high specific surface area are anatase phase and show fine photocatalytic properties for degradation of RhB under UV light irradiation. TiO2nanotubes show better photocatalytic activity than TiO2nanofibers resulting from the high specific surface area and porous structure.2. On the basis of electrospun TiO2nanofibers and nanotubes, NiO/TiO2P-N junction composite nanomaterials were prepared by a simple one-step solution method. The NiO/TiO2P-N junction photocatalysts with various content of NiO were prepared by changing the mass fraction of NiO precursor solution. The photocatalysis of the NiO/TiO2P-N junction photocatalysts with various content of NiO were investigated. It is found that the prepared NiO/TiO2P-N junction photocatalyst show optimal photocatalytic activity when the mass fraction of solution is1.5wt%. The photocatalytic mechanism of the NiO/TiO2P-N junction was proposed. With the content increase of NiO, the ratios between anatase and rutile of TiO2are changing. The recombination of photogenerated electron-hole was effectively inhibited by the heterojunction structure between NiO and TiO2and the homojunction structure between TiO2anatase and rutile, resulting in the improved photocatalytic activity of NiO/TiO2composite.3. Based on electrospun TiO2nanofibers and nanotubes, GR-TiO2nanofibers (GR-TiO2NFs) and GR-TiO2nanotubes (GR-TiO2NTs) were prepared by Hummers method and hydrothermal process. GR-TiO2NFs and GR-TiO2NTs are collectively called Graphene-TiO2(GR-TiO2) nanocomposites. The response of GR-TiO2nanocomposites was extended to visible light region. Compared with TiO2nanomaterials, GR-TiO2nanocomposites show enhanced photocatalysis under visible light irradiation. The hydrothermal treatment duration affects the photocatalysis of GR-TiO2nanocomposites. It is found that the3h is the optimal duration for obtaining the highest photocatalysis. Meanwhile, the results show that GR-TiO2NTs samples show higher photocatalytic activity than GR-TiO2NFs samples arising from the high specific surface area and light-trapping effect. The mechanism of GR-TiO2was discussed.In this thesis, the approaches for improving the photocatalysis of TiO2are proposed:(1)the recombination of photogenerated electron-hole was effectively inhibited by preparing the NiO/TiO2P-N junction composite nanomaterials;(2) the response of TiO2was extended to the visible light by preparing GR-TiO2nanocomposites. Based on the experimental results, the mechanism of each structure was discussed. |
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