Fabrication of Nb/V co-doped TiO2 thin films and study of structural, optical and photocatalytic properties

In this study, different samples of Niobium and Vanadium co-doped titania  thin films (5-10-15 mol% Nb and 5-10-15 mol% V) were prepared via sol−gel dip coating method, using niobium chloride as niobium precursor, ammonium metavanadate as vanadium precursor, and titanium (IV) butoxide (TBT) as titanium precursor. The effects of doping amount on the structural, optical, and photo-catalytic properties of formed thin films have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis absorption and transmission electron microscopy (TEM). XRD patterns showed a decrease in peak intensities of the anatase crystalline phase by increasing the Nb/V dopant and doping inhibition effect on the grain growth, and revealed that all samples contained only anatase phase (T= 475 ºC). The photo-catalytic activity of the thin film was measured on degradation rate of methylene blue (MB) solution under UV irradiation. Highest photo-catalytic activity of doped TiO2 thin films were measured in the TiO2–5 mol% Nb-15 mol% V sample (TNV4). Small granular crystallites of 10-15 nm 2D diameter were observed in electron microscope micrographs.