Structural, Morphological, Optical and Photocatalytic Properties of Os and N Co-Doped TiO2 Films

In the present work, Os and N co-doped TiO2 films were first prepared using a reactive RF magnetron sputtering of Ti–Os metallic target. The effect of Os concentration varying from 0 to 3.0at.% on structure as well as morphology and subsequent changes in optical and photocatalytic properties were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), optical absorption spectra and photoluminescence (PL) spectroscopy. XRD and SEM results show that the co-doping of Os and N favors the crystal growth of TiO2 and leads to a low anatase thermal stability relative to N monodoping. The band gap of the N/Os co-doped films is reduced from 3.42 eV to 3.22 eV compared with the N-TiO2 film. PL investigation further exhibits the effects of Os doping on the electronic structures and defects in N-TiO2.The photocatalytic activities of the films were evaluated by the degradation of methylene blue in aqueous solution under UV light. It was found that the photocatalytic activity increases with increasing Os content first, and then decreases after the optimal Os content. Therefore, the photocatalytic activity of Os/N co-modified TiO2 photocatalysts can be adjusted by the Os content.