Photocatalytic activity of doped TiO2 coatings prepared by sputtering deposition

Nitrogen-doped titanium oxide films were deposited at different N2/O2 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 (1 0 1) preferred orientation and the crystallinity of TiO2 − xNx films decreases as increasing the nitrogen flow rate. The proper N2/O2 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.