Influence of Ag on the properties of Ag combined Nb-doped TiO2 (TNO) thin films deposited by a co-sputtering process

Nb-doped TiO2 (TNO) is known as a multifunctional thin film. In this study, Ag was added to TNO thin films via a co-sputtering methodology to improve the properties of the films. X-ray diffraction, scanning electron microscopy and Raman spectroscopy were used to characterize the samples. The UV–Vis spectra indicated that the transparency of the samples decreased as the Ag content increased. The photocatalytic properties of the co-sputtered films were evaluated by photodegrading a methylene blue (MB) solution under ultraviolet (UV) radiation using back-side illumination; i.e., the UV light reaches the thin film through the Corning glass instead of the MB solution. By adding Ag into TNO films, their photocatalytic property significantly improved. The 2-min Ag-TNO film showed a maximum photocatalytic efficiency (k = 0.034 min−1) and good transparency of 70% in the visible range. Nevertheless, adding too much Ag led to a negative photocatalytic performance. The results suggested that the co-sputtering process is an efficient method to combine Ag with TNO thin films to improve their photocatalytic performance.