Photochemical activity of TiO2 nanotubes

TiO 2 is well known as a low-cost, highly active photocatalyst showing good environmental compatibility. Recently it was found that TiO 2 nanotubes promise to enable for high photocatalytic activity (PCA). In our experiments, we studied the PCA and spectroscopic properties of TiO 2 nanotube arrays formed by the anodization of Ti. The PCA efficiency related to the decomposition of methylene-blue was measured. To obtain reliable data, the results were calibrated by comparing with standard materials like Pilkington Activ™ which is a commercially available self cleaning glass. The studies included a search strategy for finding optimum conditions for the nanotube formation and the investigation of the relationship between PCA and annealing temperature. TiO 2 nanotubes of different shapes and sizes were prepared by an anodization of Ti foil in different electrolytes, at variable applied voltages and concentrations. The photo-dissociation of methylene-blue was detected spectroscopically. For the optimized material, an enhancement factor of 2 in comparison to the standard reference material was found. Furthermore, femtosecond-laser induced photoluminescence and nonlinear absorption of the material were investigated. Possibilities for further enhancements of the PCA are discussed.