Low-reflective and super-hydrophilic properties of titanate or titania nanotube thin films via layer-by-layer assembly

Transparent nanotube films of hydrogen titanate were fabricated by a layer-by-layer self assembly. Titania (anatase) nanotube films were also obtained by annealing titanate nanotube films at 673 K in air. Both types of film had an optically low reflectivity and a high transparency compared to polycrystalline anatase thin films. The low reflectivity and the high transparent properties of the nanotube films are due to their nanostructural porosity, i.e. the inner cavities of the nanotubes and the void spaces between nanotubes. Thin films of titanate and titania nanotubes became super-hydrophilic with a water contact angle of zero degrees under UV illumination, but the water contact angle of polycrystalline anatase thin films did not decrease below five degrees. The highly hydrophilic surfaces of the nanotubes are attributed to their nanostructural morphologies. (c) 2006 Elsevier B.V. All rights reserved.