Enhanced photocatalytic activity of TiO₂ nanostructures produced by anodic oxidation of pre-deformed Cp–Ti

Arrays of TiO₂ nanotubes were prepared on pre-deformed commercially pure titanium (Cp–Ti) foils by anodic oxidation in 1 vol.-% HF-based electrolyte. Prior to the anodic oxidation, the samples were deformed by uniaxial tension and cold rolling at room temperature in three different strain levels. Following the anodic oxidation, the samples were annealed at 450°C to obtain crystalline anatase structure. Effects of the deformation on the produced nano structures were investigated by characterisation studies and photocatalytic activity tests including methylene blue degradation test, photoluminescence, and UV–Vis diffuse reflectance spectra analyses. The results showed that the induced strain has a remarkable effect on the nanotube morphology. It also led to a decrease in the crystallite size in the uniaxial tensioned and cold rolled titanium foils. As a result of the morphological and structural changes, the photocatalytic activity of the samples increased with cold rolling strain, and uniaxial tension strains up to a critical level.