Designing TiO2 Based Nanostructures by Control of Surface Morphology of Pure and Silver Loaded Titanate Nanotubes

The synthesis and the morphological transformations of pure and silver loaded titanate nanotubes into anatase titania nanostructures under relatively mild temperatures (500 °C) have been discussed. At first, it will be shown that the transformation of titanate into titanium oxide leads to the formation of TiO2 particles, and then the role of the silver, in affecting morphology, crystallinity, and optical properties of the nanostructures, is highlighted. Morphology and structure of the titanate precursor and of the formed TiO2 particles (both pure or silver loaded) have been investigated by means of Brunauer-Emmett-Teller and powder X-ray diffraction analyses, high resolution transmission electron microscopy, atomic force microscopy, and scanning electron microscopy. Surface and optical properties have been explored by means of Fourier transform infrared (FTIR) and ultraviolet-visible diffuse reflectance spectroscopies. With regard to the vibrational properties of the obtained materials, the comparison of FTIR features of adsorbed CO on pure and silver exchanged titanates, with respect to pure and silver loaded TiO2, have been reported for the first time. It will be shown that all the materials (as prepared, either in the hydrogen or in the silver exchanged form and those obtained after thermal treatments) show better properties than the commercial TiO2 precursor and in general than those obtained by solid state reactions (P25), in terms of specific surface area and porosity.