Preparation And Characterization Of TiO₂ Nano-composite Materials

As a new material, inorganic nanometer material means the size under 100nm and has been attracted widely attentions because of its unique characteristics such as small size, complex configuration, high specific surface area. It is supposed to have important applications in catalysis, environmental protection, medicine and health, electronic industry and so on. To satisfy all kinds of application, preparation of multifunctional nano-composite materials has become an important aspect of research.The first part of this dissertation is a review which focuses on the special performances, preparation methods, characterizations and applications of the inorganic nanometer materials. The second part deals with the preparations of needle-like Fe₂O₃ coated titania nano-composite particles, TiO₂ nanotubes, TiO₂ nanotubes supported Ag, Au, Pt nanoparticles, as well as the characterization of the samples by XRD, TEM, SEM, UV-Vis, EDS, Raman spectrum and so on.A new type of needle-like α-Fe₂O₃ coated titania composite particles with hollow interiors were synthesized via a simple solution synthesis route. TEM image of the composite particles clearly showed that the titania spheres were uniformly coated by the needle-like α-Fe₂O₃. XRD results of the products showed there were two distinct peaks (104) and (110) of the hematite phase besides the anatase phase of the titania in the spectrum of the composite particles. UV-vis absorption spectra of the product showed a strong absorption peak at 390 nm, and also showed a wide absorption band. The absorbance intensity of the composite particles in the visible light range increased greatly compared to the single titania particles (prepared without the presence of α-Fe₂O₃). Increase of the amount of Fe₂O₃ did, of course, increase the absorbance in the visible light range. Although the formation mechanism of the composite particles is not yet clear and is still under investigation, this work presents an easy method to synthesis the composite materials of the needle-like α-Fe₂O₃ and the titania particles with tailored microstructures.TiO₂ nanotubes were prepared under normal pressure at a temperature of 120 ℃. A process, through which the TiO₂ powders were converted into TiO₂ nanotubesprogressively (powder-sheet-nanotube), was found with transmission electron microscope observations. The diameter of the nanotube was about 8 nm while the tube length ranging between 100 nm and 300 nm.Ag, Au, Pt nanoparticles supported on T1O2 nanotubes were prepared by microwave assisted heating polyol process. TEM images showed that microwave prepared Ag, Au, Pt nanoparticles supported on T1O2 nanotubes were small and well dispersed on the surface of the T1O2 nanotubes. The average diameter of Ag nanoparticles is about 5.4 nm while that of Au nanoparticles was about 6.2 nm. The metal content was calculated from EDS measurements to be 8.8 % for Ag, 6.9 % for Au and 6.8 % for Pt respectively. UV-Vis absorption spectra showed that the absorbance of Ag/TiC>2 nanotubes and Au/TiO2 nanotubes in the visible range increased greatly compare to the single titania nanotubes.