Effect of composition electrolyte on the morphology and photocatalytic activity of anodized titanium nanoporous

The morphology of titanium dioxide and titanium dioxide-tungsten trioxide nanocomposite films fabricated by anodizing in a glycerol solution containing 0.13 M NH4F and different quantity of Na2WO4 was investigated as a function of sodium tungstate concentrations. The effects of sodium tungstate concentration on the surface morphology were observed by scanning electron microscopy (SEM). It was clearly seen that highly ordered titanium dioxide nanotube array films were formed in an anodizing solution free of tungsten. With a gradual increase in the sodium tungstate concentration, these nanotube structures changed to nanohoneycombs, nanoporous and compact films without porosity. These findings indicate that the composition of anodizing bath is very important factor in determining the surface and structure of anodized films. UV-Visible spectroscopy data show that the band gap decrease with increasing sodium tungstate from 3.23 eV for bare titanium dioxide to 2.78 eV for titanium dioxide-tungsten trioxide nanocomposites. Photo catalytic activity of samples was evaluated by measuring the degradation of methylene blue dye under visible light irradiation. Results revealed that nanocomposite films have excellent photo catalytic performance.