Synthesis and Characterization of Titania Nanostructures on Glass by Al Anodization and Sol−Gel Process

Abstract

Titania nanostructures with larger surface areas are fabricated on a glass substrate by anodization of sputtered aluminum and the sol−gel process, and the structural characteristics of the nanostructures are investigated. Highly pure aluminum film (99.99%, ≈2 μm), which is deposited on a glass substrate with a conductive tin-doped indium oxide (ITO) layer, is first anodized potentiostaticly in a phosphoric acid solution to obtain porous alumina structures. The anodic alumina is then used as a host or template to synthesize porous Al2O3/TiO2 composite nanostructures through a sol−gel process. Finally, a TiO2 nanotubules array with contours of porous anodic alumina is fabricated on glass by removing the alumina template selectively. The resultant TiO2 is 4−20 nm polycrystalline of anatase structure with (101) preferential orientation. Titania nanostructures have large surface areas and exhibit a high transmittance in visible light and a strong absorbance within ultraviolet range in UV−vis spectra. Moreover, the fabrication of composite TiO2−xSiO2−xTeO2 (x = 2.5%, 5%) nanostructures is also investigated. Addition of appropriate SiO2 and TeO2 to TiO2 enhances not only the adhesion to the substrate but also the mechanical strength of the nanotubules, while showing little effect on the crystallinity and the UV−vis absorbance of TiO2.