Structure, chemical state and photocatalytic activity of TiO2−x nanostructured thin films by glancing angle deposition technique

Nonstoichiometric titanium dioxide nanostructured thin film (TNF) has attracted a range of interest in the green energy field. In this paper, we introduce the glancing angle deposition (GLAD) technique to produce the amorphous TNFs with discrete nanoscale columnar structures. In order to improve the crystallinity and/or gain the Ti3+ doped states, amorphous TNFs were annealed at 400 °C in air or H2. XRD, SEM, AFM, XPS and PL were used to characterize the crystallization structure morphology, chemical state, PL properties of the TNFs with different annealing conditions. Photocatalytic activities of the samples were reflected by decolorization experiments of methylene blue (MB) solution irradiated by the simulated sunlight light of AM 1.5 G. The photocatalytic activity of amorphous TNF is higher than that of conventional TiO2 thin film, indicating the prominent properties of nanostructures. Compared with annealing in air, the photocatalytic activity of TiO2-x nanostructures annealed in hydrogen is further increased and higher. The results demonstrated that Ti3+ and oxygen vacancies were beneficial and played the dominant role for the enhancement of photocatalytic activity.