Abstract: Well-aligned and uniform titanium dioxide nanotube array films were fabricated in-situ on titanium substrate by electrochemical anodic oxidation. The resulting amorphous films were crystallized and annealed at 500 ^oC in different atmospheres such as the oxygen, air, argon, and hydrogen. The photoelectrocatalytic performance of the as-annealed nanotube array films was investigated using methane blue (MB) as a target pollutant. The MB degradation kinetics met the law of first order reaction and the rate constants were 4.967, 3.127, 1.989, and 1.625 h^-1 at 0.5 V bias, respectively. Electrochemical impedance spectroscopy analysis revealed that the MB degradation was governed by the charge transfer characteristic of the nanotube. The improvement of light absorbance and excitation and the lower transfer impedance might be critical factors for the efficient photoelectrocatalysis of TiO₂ array films annealed in oxygen.

Key words: titanium dioxide, nanotube array, anodic oxidation, photoelectrocatalysis, methylene blue, heat treatment