The influence of oxidation time on the morphologies of TiO2 nanostructures

Highly-ordered TiO2 nanostructures have been successfully fabricated by anodic oxidation method on the surface of pure titanium and Ti film deposited on the Si substrates using 20 V of the DC voltage in 0.5% HF electrolyte. X-ray diffractometer (XRD), Raman spectroscopy and field emission scanning electron microscope (SEM) were used to characterize the transformations of morphologies and structures on the TiO2 nanostructures. The experimental results showed that the final morphologies of the nanostructures were time-dependent. The tube architectures were firstly fabricated, and with the increase of the oxidation time, the tube morphologies were ruined and the rod-like morphologies were formed. When the Ti films on the Si substrates were anodized, a new kind of porous nanostructures was formed on the surface of the Ti foils, which are different to the previous reports. The formation mechanisms of these nanostructures were also briefly discussed.