Abstract: A highly ordered TiO2 nanotube layer was fabricated on fluorine-doped tin oxide-coated glass substrate (FTO) by potentiostatic anodization of pure titanium film at room temperature, which was deposited by radio frequency (RF) magnetron sputtering. The structure and the composition of the as prepared TiO2 nanotubes were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV-Vis transmission spectra, and photoelectrochemistry methods. The results showed that the Ti films converted to TiO2 nanotubes of 380 nm length, 90 nm pore diameter, and 15 nm wall thickness at the voltage of 20 V for 50 min. After annealing at 500 ℃ for 6 h in air, the anatase phase of TiO2 nanotube/FTO transparent electrodes were obtained, which had an average transmittance of 80% in visible wavelength range. The bandgap of TiO2 was determined as 3.28 eV, with a bandgap tail extending to 2.6 eV. Moreover, the photoelectrochemistry measurements indicated that the crystallized electrode exhibited a significant improvement of photoelectrochemical current response in comparison with the as-anodized electrode, and both the electrode potential and UV-illumination surely enhanced the effective separation of the electron-hole pairs, leading to the fact that the photo-induced electrons transferred quickly to the conducting glass via external circuit and formed photocurrent.

Key words: RF magnetron sputtering, Ti thin films, Anodic oxidation, TiO2 nanotube arrays, Transparent electrode