Transition Metal Oxides Nanostrucutures: Controlled Synthesis, Assembly And Their Properties

Owing to variety of electronic structures, nanostructured transition metal oxides have exhibited strongly potential applications in optics, magnetics, catalysis and batteries. Preparing nanostructured transition metal oxides, investigating their possible formation mechanism and consequent controlling the size, composition and physical properties could be of the key importance. Apart from the synthesis, the organization of the as-obtained nanostructures towards advanced and complex superstructures also play a very important role in materials science, which would help the design of functional materials as the corresponding requirement. In this dissertation, systematic explorations have been carried out on synthetic strategies of nanostructured transition metal oxides, formation mechanisms, controllable organization and their properties.Based on the phase transfer and separation, the uniform yttrium phosphate hydrate nanocrystals with controllable size and shape have successfully prepared via a solution-base path way. Based on experimental facts, a possible formation mechanism was also proposed and applied to the preparation of the other lanthanide phosphates nanocrystals. By utilizing the multiple interactions between the long chain alkyl molecules, which absorbed on the surface of the nanocrystals, the 2 dimensional (2D) assembled superstructures were readily formed.Based on the special crystal structure of ammonium cerium nitrate, a novel method for synthesis of monodisperse 3nm cerium oxides nanocrystal in large scale was developed rationally. Furthermore, 3D assembled colloidal particles with high ordered internal secondary structures were also prepared in one step through increasing the concentration of the precursor in the synthetic system. A facile method was established for the synthesis of uniform titanium oxide nanocrystals with different shapes and sizes. Based on the constructed positive micelle, the as-obtained nanocrystals were organized into functional colloidal nanospheres. Systematical studies of their electronchemistry and catalytic properties indicated promising applications of the assembled products materials in catalysis and Li-ion battery.A general method for synthesis of ultrathin nanostructures was developed based on the rational artificial lamellar mesostructure. The as-obtained products can be organized into various ordered superstructures, which indicated that the synthesis and organization was couple together successfully.