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Chemical Synthesis and Controlled-growth of Low-dimensional Nanomaterials

Author: ZhangYunXia
Tutor: LiGuangHai
School: Institute of Solid State Physics
Course: Condensed Matter Physics
Keywords: TiO2 nanowires TiO2 mesoporous hollow spheres surfactant CTAB one-dimensional Sb2O3 nanomaterials Sb2Se3 hollow nanospheres indium hollow spheres indium nanotubes
CLC: TB383.1
Type: PhD thesis
Year: 2004
Downloads: 640
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Abstract


Quasi-one-dimensional nanomaterials have attracted worldwide attention and laid some foundation for the nanodevices due to their unusual optical, electronic, magantic, mechanical and catalytic properties. It is well known that the properties of nanomaterials are sensitively dependent on both shape and size. Therefore, the most important problem faced by the scientists is how to fabricate nanostructures with the controllable shape and size. In addition, inorganic hollow spheres of nanometer to micrometer dimensions have opened up various new applications fields, such as the controlled release capsules, artificial cells or drug delivery, light-weight structural materials, catalysts and etc. due to their low density, large specific area, mechanical and thermal stability, and surface permeability. Based on these considerations, we have prepared not only TiO2 nanowires and one-dimensional Sb2O3 nanomaterials with the controllable shape, but also Sb2Se3, indium, and TiO2 hollow spheres by chemical method at low temperature.1. Single-crystalline TiO2 nanowires with mass-production and high quality have been prepared by a simple hydrothermal process by adopting rutile nanocrystals as raw-materials. The photoluminescence intensity of TiO2 nanowires is higher than that of nanocrystals, indicating that TiO2 nanowires might have higher activity than nanopowders and will have potential applications in photocatalysts and photoelectronics. 2. TiO2 mesoporous hollow spheres with higher aspect ratio have been prepared through a sol-gel method at room temperature. In addition, TiO2 mesoporous spheres have also been synthesized by changing the experimental condition.3. Sb2O3 nanotubes have been successfully synthesized by a surfactant-assisted solvothermal process. The growth mechanism of nanotubes is discussed and the structure with half tube or half sheet provided strong proof for the rolling up mechanism of Sb2O3 nanotubes. At the same time, Sb2O3 nanobelts, nanorods, and needle-like fibres have been respectively prepared by carefully adjusting the reaction factors. That is, we have realized the shape control synthesis of one-dimensional Sb2O3 nanomaterials.4. Sb2Se3 hollow nanospheres with different sizes have been prepared by a surfactant-assisted solvothermal route under different temperatures. The structures of these hollow nanospheres have been further characterized by Raman spectrum. The optical gap of hollow nanospheres have an obvious blue shift due to quantum-confined effect compared with the value of Eg=1.2 eV for single crystals of Sb2Se3, which might originate from the smaller size of the hollow spheres walls. In addition, indium hollow nanospheres and nanotubes have been synthesized by a template-free solvothermal process.

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