抄録
The photo-corrosion of the TiO2 oxide film (9.2 nm thick) formed anodically on titanium was studied in 0.1 M sulfuric acid solution by in-situ ellipsometry during ultra-violet (uv) light irradiation of 325 nm wavelength. The uv light irradiation induces some changes in the oxide film as observed by ellipsometry. From the change of the ellipsometric parameters, reduction of the oxide film thickness was estimated. It was estimated that 5 % of photo-induced current is consumed for the photo-corrosion of the oxide film. The photo-corrosion rate is proportional to the anodic bias relative to the flat-band potential and to the uv light intensity. The mechanism of the photo-corrosion was discussed in terms of a photo-effect of n-type semiconductive oxide electrode; the photocorrosion is induced by an accumulation of photo-excited holes at the oxide surface, which may increase interfacial potential difference at the oxide surface and weaken the Ti-O bond of the oxide.
