Laser ablation of TiO_(2-2x)N_x targets for efficient N-doping into Anatase TiO2 photo-catalytic films

摘要

Among the well-known photo-catalytic materials, the anatase TiO2 is the most promising in terms of its chemicalstability and high reactivity. It is known that the photo-catalytic activity under the visible light irradiation can beenhanced by nitrogen doping into the anatase, because the substitutional nitrogen produces an impurity state whichabsorbs the visible light. In this paper, we will report on the properties of the nitrogen doped films with different dopantconcentrations. The anatase films are prepared by KrF excimer pulsed-laser ablation of TiO2-xNx targets. The films aredeposited on the (100) LaAlO3 substrate which has a good lattice matching with anatase (~ 0.2%). First, we discussthe optimization of the growth conditions. To prepare the nitrogen doped anatase thin films, we have developed a lowtemperatureepitaxy. The growth of anatase-type TiO2 was confirmed using an x-ray diffraction (XRD). The nitrogenincorporation was evaluated by an x-ray photoemission spectroscopy (XPS). The as-grown films have very smoothsurface and exhibit good amphiphilic properties. Then, we present the photo-catalytic activity of the films. The nitrogendoping concentration was varied by adjusting the amount of nitrogen in the ablation targets. The photo-catalytic activitywas measured by the decomposition rate of methylene blue solution under a fluorescent light illumination.