Titanium Vanadium Oxide Thin Films Prepared by Thermal Oxidation of Titanium-Vanadium Alloy as Photocatalyst for Methylene Blue Degradation under Visible Light

In this work, titanium-vanadium oxide composite thin films were prepared by thermal oxidation of vanadium and titanium metallic alloys, at 500 °C under air atmosphere. The metallic alloys, with different vanadium contents, were obtained by co-sputtering of vanadium and titanium targets on glass and silicon substrates. The films were characterized by means of scanning electron microscopy (SEM), x-ray diffraction, Raman spectroscopy, infrared spectroscopy, x-ray photoelectron spectroscopy, and UV–Vis spectroscopy. In addition, photodegradation of methylene blue (MB) in aqueous solution, on these composite films, under visible light, was also evaluated. SEM images show nanostructured films with nanospherical or nanobaranched surface morphologies. Furthermore, the results reveal that at low vanadium (V) content, the films consist of one or mixture of amorphous phases (TiVOx or TiOx plus VOx, or both). In the case of films with higher V content, two separated phases, namely V2O5 and amorphous TiOx are obtained. The UV–Vis analyses demonstrate a redshift of optical absorption over a broad band of optical frequencies for films with high V content. Furthermore, these films manifested a good catalytic activity toward MB degradation with degradation rate of 78% after 120 min of visible light irradiation. Such composite thin films can be promising not only for photocatalytic applications, but also for photonic and sensing devices.