Photocatalytic behavior of different titanium dioxide layers

Many recently developed applications are related to the photocatalytic behavior of semiconductive oxides. Among the different oxides, titanium dioxide (TiO2) is one of the most interesting due to its high photocatalytic efficiency towards a great number of reactions and to its hydrophilic properties. Aim of this work is the evaluation and comparison of the photocatalytic properties of different crystalline titanium dioxide films, directly grown on titanium substrates by surface anodization (eventually followed by thermal annealing) and by Pulsed Laser Deposition (PLD) on titanium and silicon substrates, followed by thermal annealing. The structure and morphology of the layers were characterized by Scanning Electron Microscopy and X-Ray Diffraction and photocatalytic tests on stearic acid mineralization were performed. Results showed that the PLD layers possess a higher photocatalytic efficiency than anodized titanium. This can be attributed to the microstructured/microporous morphology of the related surfaces. Instead, PLD TiO2 layers with a relatively high content of the rutile phase have a reduced photocatalytic efficiency with respect to mainly anatase containing layers. (C) 2006 Elsevier B.V. All rights reserved.