Construction and photoelectrocatalytic properties of TiO₂ nanotubes arrays on titanium substrates

In this paper, vertically aligned nanotubes arrays of titanium oxide were fabricated on the surface of titanium substrate by direct anode oxidation with HF being the supporting electrolyte. Under the condition of applying the same bias on the electrodes, a higher anodic photocurrent of the TiO₂ nanotubes electrode was obtained than that of TiO₂ film electrode, which is due to the larger specific surface area, novel microstructure and higher efficient surface-interface electron migration of nanotube electrode. The degradation of a textile azo dye, Acid Orange 7 (AO7), in aqueous solution with TiO₂ nanotubes electrode was carried out using photoelectrocatalytic (PEC) process, comparing with electrochemical process (EP) and photocatalytic (PC). A significant photo-electrochemical synergetic effect was observed. The reason is attributed to the surface state characteristics and higher separation efficiency of photo-generated charge carrier of nanotube system.