Photoactivity of Sol–Gel Derived Nitridated Zn x Ti y O z -Films

Zn x Ti y O z layers were prepared by sol–gel method and nitridated yielding photoactivity in the visible wavelength region. The condensation process of these nanostructures and their subsequent sintering was followed by using XRD-, UV/Vis-, micro-Raman-, FTIR- and thermal analysis measurements. The oxynitride formation during the nitridation process was confirmed by XPS and UV-Vis spectroscopy. The photocatalytical studies of methylene blue (MB) degradation revealed the activity of coloured oxynitride layers under the visible light irradiation. Furthermore, a metachromasy of MB infiltrated within the nanostructured films was observed for the first time. This blue shift in the optical absorption spectrum of MB became even more pronounced during the photodegradation process of this dye.