Search

Anodic oxidation of titanium substrate in an electrolyte comprising ammonium nitrate in ethylene glycol is an innovative technique for fabricating a visible-light-responsive photocatalytic titanium dioxide (TiO 2 ) layer. In this study, the effects of the duration of anodization on photocatalytic activity were investigated to improve its performance. Surface morphologies of the fabricated layer were comparatively flat for small durations of anodization, but small cracks were generated when anodizing for over 120 min. The thickness of the layer increased with treatment time up to 60 min, beyond which time no further increase in thickness was observed. The predominant structure of the oxide layer was TiO 2 with a rutile structure, and its amount increased with longer treatment duration. Nitrogen doping was observed in the layer regardless of the duration although its chemical state and photocatalytic activity varied depending on the duration. Under ultraviolet light irradiation, the change in activity was small, whereas the activity was drastically enhanced with longer treatment duration in the case of visible light irradiation. Based on these results, we concluded that the optimum duration of anodization is 60 min in the present setting because a TiO 2 layer showing good photocatalytic activity without any surface cracks could be formed. [ABSTRACT FROM AUTHOR]

To provide semi-permanent antibacterial function for titanium medical implements, such as micro-tweezers, hemostatic forceps, and needle holders, a visible-light responsive nitrogen-doped titanium dioxide (TiO 2 ) layer that strongly adheres to Ti materials was fabricated through anodization in an electrolyte comprising ammonium nitrate in ethylene glycol, followed by heating at 723 K in air. The predominant structure of the oxide layer was TiO 2 with a rutile structure that contained ca. 1 at.% of incorporated nitrogen. The outward appearance of the oxide layer was quite smooth, and the topographic microstructure was a flat surface that included small pores. The thickness of the surface layer was approximately 10 μm, and the layer strongly adhered to Ti substrates. This fabricated anodic layer acted as a photocatalyst both under UV-light and visible-light illumination, and showed excellent antibacterial performance under both types of illumination. Anodic oxidation in a nitrate/ethylene glycol electrolyte is an innovative surface modification technique that can be used to simply form visible-light responsive photocatalytic antibacterial coatings on biomedical Ti materials. [ABSTRACT FROM AUTHOR]