An electrochemical strategy of doping Fe3+ into TiO2 nanotube array films for enhancement in photocatalytic activity

Highly ordered Fe3+-doped TiO2 nanotube array films were fabricated directly by the electrochemical anodic oxidation of pure titanium in an HF electrolyte solution containing iron ions. The morphology, structure and composition of the as-prepared nanotube array films were characterized by SEM, Raman and XPS. The effects of dopant amount on the morphologies, structure, photoelectrochemical property and photoabsorption of the TiO2 nanotube array film were investigated. The results showed that Fe3+ was successfully introduced into the nanotube array film. Compared with the undoped TiO2 nanotube array film, the photocurrent of Fe3+-doped TiO2 nanotube array films increased obviously. The absorption edge of Fe3+-doped TiO2 nanotube array films appeared to be red shifted. The photocatalytic activity of Fe3+-doped TiO2 nanotube array films was evaluated by the removal of methylene blue (MB) aqueous solution. A maximum enhancement of photocatalytic activity was achieved for Fe3+-doped TiO2 nanotube array film prepared in 0.10 M Fe(NO3)3+0.5% HF electrolyte under UV irradiation, which attributes to the effective separation of photogenerated electron–hole upon the substitutional introduction of appropriate Fe3+ amount into the anatase TiO2 structure.