Synthesis and characterization of nitrogen and zirconium ions doped TiO<sub>2 </sub>films for photocatalytic application
Codoped by nitrogen and zirconium ions titania thin films have been obtained by sol-gel and pulse laser deposition (PLD) methods to investigate the influence of zirconium ions as well as the synthesis procedure on the efficiency of nitrogen incorporation into semiconductive lattice that, in turns, effected on the film activity under ultraviolet and visible light. The composition of the films and the synthesis methods changed the optical properties of the materials as namely almost no effect of both doping agents on the band gap energy value was noted for the films obtained by pulse laser deposition technique, while its sharp narrowing was observed for nitrogen doped titania sol-gel sample. Additionally, the high absorption in the visible part of the spectra with the different maxima were registered for sol-gel films. Substitutional and interstitial nitrogen incorporation occurred in the case of sol-gel titania doped by both doping agents and only nitrogen, respectively. However, both types of nitrogen atoms were detected by X-ray photoelectron spectroscopy measurements for the laser deposited films and the relative intensity of its state was dependent whether single or double doping agents was used. Incorporation of each doping agent in titania matrix positively influenced on the photocatalytic activity of the sol-gel films under both ultraviolet and visible light. In the case of pulse laser deposited films, the presence of double doping agent stimulated the activity under UV light and the doping only by nitrogen led to the increase of photoactivity in visible light.