Decomposition ability and bioactivity of photocatalytic TiO2 based layers prepared by reactive pulse magnetron sputtering
Crystalline TiO2 layers show interesting properties for different applications. Rutile layers can be used as optical layers with high refractive index and as protective layers with good mechanical properties. Both, anatase and rutile are photo-semiconductors and exhibit in a different degree photocatalytic, photo-induced hydrophilic and antifogging properties. For a better control of the TiO2 deposition and thin film properties a special deposition system has been developed: a reactive pulse magnetron sputtering (PMS) system. Nitrogen doped TiO2 layers were deposited on glass at dynamic deposition rates of about 45 nm.m/min (corresponding to about 160 nm/min in a stationary coating system). Measuring the decrease of the water contact angle by UV irradiation the layers were investigated regarding their photo-induced hydrophilicity. The ability to decompose organic matter was evaluated by measuring decolouration of a solution containing methylene blue organic dye as well as by measuring the decrease of fluorescence of a thin organic dye film. Using this methode photocatalytic acitivity by UV and visible irradiation can be effectively proved. Results regarding nitrogen doped TiO2 thin films as well as Ti-based mixed oxides (TixMeyOz) and a comparison to commercial samples will be presented. Bioactivity was examined by the example of algae (Desmodesmus subspicatus) and bacteria (Micrococcus luteus). Tested microorganisms were effectively inhibited due to photocatalytic activity of the TiO2 layers.