Self-assembled TiO2 nanotube arrays films with controllable length for photocatalytic decoloration of methylene blue

Self-assembled TiO₂ nanotube array on Ti substrate was fabricated by using an electrochemical anodic oxidation. The morphology, crystalline phases and photochemical properties of nanotube arrays were characterized. The photocatalytic activity of the nanotube arrays were evaluated by the decoloration of methylene blue(MB) in aqueous solution using the light source of 300W mercury lamp. The experimental results demonstrated that the length and crystalline phases of nanotube array effected on the MB decoloration of aqueous solution, and the 14.01μm-long nanotube array, which was the optimal length, showed the maximum photodegradation efficiency. Besides, the formation mechanism of nanotube array and the MB adsorption into nanotube arrays were also illustrated briefly.