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Three steps anodization process is used to synthesize highly ordered and uniform multilayered titanium oxide (TiO 2 ) nanotubes and effect of different anodization voltages are studied on their physical properties such as structural, morphological and optical. The crystalized structure of the synthesized tubes is investigated by X-ray diffractometer analysis. To study the morphology of the tubes, field emission scanning electron microscopy is used, which showed that the wall thicknesses and the diameters of the tubes are affected by the different anodization voltages. Moreover, optical studies performed by diffuse reflection spectra suggested that band gap of the TiO 2 nanotubes are also changed by applying different anodization voltages. In this study using physical investigations, an optimum anodization voltage is obtained to synthesize the uniform crystalized TiO 2 nanotubes with suitable diameter, wall thickness and optical properties.

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Titanium dioxide (TiO2) nanosheet, nanorod and nanotubes are synthesized using chemical vapor deposition (CVD) and anodizing processes. TiO2 nanosheets are grown on Ti foil which is coated with Au catalyst in CVD, TiO2 nanorods are synthesized on treated Ti foil with HCl by CVD, and TiO2 nanotubes are prepared by the three-step anodization method. Scanning electron microscopy shows the final TiO2 structures prepared using three processes with three different morphologies of nanosheet, nanorod and nanotube. X-ray diffraction verifies the presence of TiO2. TiO2 sheets and rods are crystalized in rutile phase, and TiO2 tubes after annealing turn into the anatase crystal phase. The optical investigations carried out by diffuse reflection spectroscopy reveal that the morphology of TiO2 nanostructures influencing their optical response and band gap energy of TiO2 is changed for different TiO2 nanostructures.

The titanium oxide (TiO2) nanotubes have attracted attention for their use in dye-sensitized solar cells as photoanode. In this study semiconducting cadmium sulfide (CdS) nanoparticles are grown on top opened TiO2 nanotubes arrays by radio-frequency magnetron sputtering. X-ray diffraction, scanning electron microscopy, transmission electron microscopy and diffuse reflection spectra are used to study structural, morphological and optical properties of the CdS/TiO2 bilayer.