Photocatalytic activity of doped TiO2coatings prepared by sputtering deposition

Nitrogen-doped titanium oxide films were deposited at different N-2/O-2 flow ratios by dc reactive magnetron sputtering. The films were characterized using grazing incidence X-ray diffraction, scanning electron microscopy, AFM, and UV-vis-NIR spectrophotometer. Photocatalytic activities of the samples were evaluated by the degradation of methylene blue. Experimental results have demonstrated that all the films show anatase (10 1) preferred orientation and the crystallinity of TiO2-xNx films decreases as increasing the nitrogen flow rate. The proper N-2/O-2 flow ratio condition results in the band gap narrowing and a red shift in the absorption spectra toward visible light regions. The TiO2-xNx film with high crystallinity and porous surface morphology shows the better degradation rate of methylene blue solution increases about two times than TiO2 films. (C) 2007 Elsevier B.V. All rights reserved.