The Synthesis Of1D TiO₂Nanomaterials And Surface Modification With Ag、Au Nanoparticles

Titanium dioxide (TiO2) is a kind of multifunctional semiconductor materials, because of its excellent physical and chemical properties and its promising applications such as photocatalyst, photo-electric device and ultraviolet detector, it has been attracted researchers’s attention all around the world. Compared with TiO2powders, one-demensional (ID) TiO2nanomaterials have better stability, stronger electron mobility and larger specific surface area, which is beneficial to improve the photoelectric properties. Meanwhile, the application of nano materials also depends on its morphology characteristics. Currently, the research of TiO2preparation by wet chemical method has made significant achievements, but their’s berely report about synthesise one-dimensional TiO2by vapor deposition under mild conditions due to the high melting point and low vapor pressure properties of Ti. In this paper, we report a low cost and simple vapor deposition method to prepare high crystallinity ID TiO2nanostructures with different morphology, and discussed the morphologies, structure, photoelectric performance as well as growth mechanism of the as synthesised materials, then we do a preliminary research of surface modification of TiO2nanowires, the results are summarized as follows.(1) The high crystallinity ID TiO2with different morphology was grown on Ti foils by chemical vapor deposition (CVD) method at various temperature and Pd catalyst content. We found that (1)The PdCl2:ethanol solution with Ti foils under uv-irradiation for30min,1h and2h respectively follwed by heating at the temperature of900℃for10min, SEM images showed the obtained nanowire size range from56.4to187.95nm, and the length also decrease from dozens of micron to a few microns.(2) In the case that maintain catalyst content, at the reaction temperature of700℃,730℃and730℃for30min, TiO2nanotubes, nanobelts and tower structure were obtained. XRD and Raman spectroscopy characterization confirmed that all the TiO2nanostructures are pure rutile. The vapor-liquid-solid (VLS) mechanism is the best explanation to nanowires growth. While nano film, nanobelts, and tower structure were fabricated by the combination of VLS and vapor-solid (VS) mechanism.(2) Cone TiO2nanobelts with sawteeth were synthesized by calcining Ti foils at the temperature of760℃for40min. The serrated edge is the result of different activity between Ti+and O thus lead to different growth rate in the growing process. The micro Raman imaging of single nanobelts showed that this cone TiO2structure with uniform chemical composition distribution, SPV test also showed good photoelectric response, which is helpful for the application of TiO2in optoelectronic devices.(3) Ag/TiO2and Au/TiO2composite structure were fabricated by photochemical deposition and immersion-deposition respectively. We found that the particle adsorption increased while prolong deposition time. When TiO2nanowires adsorption in Au solution for12h, its Raman spectrum blue shift in441cm-1, this is due to excessive Au particles deposited on nanowires and extrusion to the TiO2surface atoms, changing the state of TiO2surface atomic interaction. SPV curve reveals that TiO2nanowires adsorb amount of metal particles can broaden the scope of light absorption and increase response intensity, which indicates that surface modification with metal particles are beneficial to photoelectric performance.