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过渡金属氧化物一维纳米结构液相合成、表征与性能研究
Solution-Based Route to Transitional Metal Oxides One-Dimensional Nanostructures: Synthesis, Characterization and Their Properties
【作者】 王训；
【导师】 李亚栋；
【作者基本信息】 清华大学 ， 化学， 2004， 博士
【摘要】 一维纳米材料以其独特的电学、光学和力学特性引起了世界范围内科学家的研究兴趣。如何合理控制材料的定向生长,进而实现对其尺寸、维度、组成、晶体结构乃至物性的调控,对于深入研究结构与物性的关联、并最终实现按照人们的意愿设计合成功能材料具有重要的意义。本论文在过渡金属氧化物一维纳米结构液相合成新方法、新型过渡金属氧化物一维纳米结构设计合成及形成机制、所获得新型纳米结构的物性等方面进行了有益的探索。发展了二氧化锰纳米线、纳米管的低温水热制备技术。在对不同晶型二氧化锰晶体结构差异进行了充分分析的基础上,通过设计合理的化学反应,实现了对?、?、?、?等多种晶型二氧化锰纳米线的选择性控制合成,制备了二氧化锰单晶纳米管,并对二氧化锰一维纳米结构的形成进行了深入研究,提出了二氧化锰一维纳米结构形成中的层状卷曲机制,为一维纳米结构形成机制研究提供了新的思路。建立了稀土化合物低维纳米结构的液相合成新途径。报道了系列稀土化合物纳米线、纳米管及富勒烯结构的控制合成,对各种结构间的转化与关联进行了分析探讨,并对其纳米结构的光学性质进行了初步研究,为进一步探索该类具有独特结构稀土化合物的优异物理化学性质奠定了坚实的基础。发展了醇水混和溶剂热的方法,利用硅酸盐中广泛存在的链状及层状结构,合成出系列硅酸盐纳米线、纳米管结构;硅酸盐纳米管具有大的比表面积、均一的孔径分布及优异的热稳定性,初步研究表明其在室温、40atm条件下,储氢量达1.8%,经金属粒子修饰的硅酸盐纳米管则显示了优异的低温催化氧化性能,在气体的吸附与分离、汽车尾气催化等领域展示了良好的应用前景。采用简单的方法实现了对铁、钴、镍、钼等多种氧化物纳米结构的维度调控,以无外场、无模板的方法合成了Fe3O4纳米线结构。通过这些新型一维纳米结构的合成,发展了一条简单有效的制备过渡金属氧化物一维纳米结构的途径,并为新的合成方法学的建立奠定了基础。
【Abstract】 One-dimensional (1-D) nanostructures have drawn continuous research attention because of their unique electrical, optical and magnetic properties different from that of bulk and nanoparticles as well as their potential applications in mesoscopic research and nanodevices. The main challenge in this area is how to precisely control the sizes, dimensionalities, compositions and crystal structures in nanoscale, which may serve as a powerful tool for the tailoring of physical/chemical properties of materials in a controllable way. In this dissertation, valuable explorations have been carried out on the new synthetic strategies (mainly solution-based routes) to transtional metal oxides (TMO) one-dimensional nanostructures, the synthesis of new-type 1-D TMO as well as their formation mechanism and the novel physical/chemical properties of the as-obtained new-type nanostructures. The main points can be summarized as follows:A rational low-temperature hydrothermal synthetic way has been developed to selectively prepare MnO2 nanowires/nanotubes with different crystal structures, the formation of which is investigated in details and is believed to be closed related to the layer-structured ?-MnO2. A rolling mechanism has been introduced to explain the growth of MnO2 nanowires under hydrothermal conditions.Based on the anistropic structures of Lanthanide hydroxides, a new synthetic strategy has been established to synthesize rare earth nanowires, nanotubes and Inorganic fullerene-like nanostructures, and some preliminary optical properties have been studied. Owning to the interesting combination of novel nanostructures and functional compounds, these low-dimentional nanostructures can be expected to bring some new opportunities in vast research areas of and application in biology, catalysts and optoelectronic devices.Series of Silicates nanowires and nanotubes have been successfully obtained from a novel water-ethanol mixed-solution hydrothemal route. The as-obtained nanotubes have narrow size distributions, large BET surface areas and excellent thermal/hydrothermal stability, and have shown great potential in gas separation/adsorption and catalysis fields.A facile method has been illustrated to control the dimensionality of seris of transtional metal oxides including ion, nickel, cobalt and molybdenum.