Monodisperse Nanocrystalline Particles Templated By Nafion Membranes: Preparation, Characterization, And Properties

Nanocrystalline semiconductors were considered to have broad application perspectives, due to their outstanding opitcal, electrical and magnetic properties.The varies function materials with anticipated or novel physical, chemical or mechanical properties can be prepared by altering and controlling of the composition, crystal structure, dimensionality, morphology and energy band structure. It is significative of nanometer materials for both fundamental research and the practical applications. In this dissertation, Nafion membrane was used as a template to synthesized homogeneously distributed crystalline nanoparticles. Nanocomposite semiconductors and noble metal and transition metal ions modified nanoparticles were also synthesized in Nafion membrane. The synthesis method and its mechanism were researched. And the photocatalytic application for liquid system was studied, using the nanoparticles embedded in Nafion membrane as photocatalysts.The main point can be summarized as follows:Homogeneously distributed anatase TiO₂ nanoparticles with an average particle diameter of 4nm were synthesized in Nafion under atmospheric pressure and low temperature(70℃～90℃), using organic alkoxide of titanium as precursors. Swollen synergism was first observed between polar alcohol solvent and Ti(OBu)4. The synergism was advantageous to the diffusion of Ti(OBu)4 in Nafion channels and the slef-assembly in the nanometer cavity. The amount of TiO₂ was easily controlled by tuning the synergism. An efficient path to synthesized oxide by metal organic alkoxide hydrolyzing in situ in Nafion membrane was provided. The fundamental theory and the experimental evidence for the design of TiO₂ function materials and structure controlled were also presented.According to the template synthesis mechanism of ion exchange technique for sulfide in Nafion, non-ionic precursor thioacetamide (TAA) was first chosen as precursor. And homogeneously distributed crystalline CdS nanoparticles were obtained by self-assembly. The crystal granularity can be tuned by controlling the...