Fabrication and characterization of nanostructured anatase TiO₂ films prepared by electrochemical anodization and their photocatalytic properties

In this study, nanostructured anatase titanium dioxide (TiO₂) films were fabricated by electrochemical anodization of titanium first, and then annealed at 500 °C for 2 h. Effect of electrolyte concentration, anodization time and electrolyte temperature on the surface morphology of the resulting TiO₂ thin films were investigated. The phase structures, surface morphology and chemical composition were analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity tests of the samples were evaluated by the degradation of aqueous methylene blue (MB) solutions under UV light illumination for different periods of time. The results showed that the structure of nanostructured TiO₂ films depended strongly on the anodization parameters. It was found that there were micro-scale pores (<10 μm) and nano-scale pores (diameter in the range from 40 to 70 nm) on the anodized titanium surfaces. This study indicated that structures, surface morphology, and surface area of the nanostructured anatase TiO₂ films played an important role on their photocatalytic performance. The results clearly proved that nanostructured anatase TiO₂ film prepared with optimum process parameters resulted in enhancement of the photocatalytic activity.