Photocatalytic activity and photo-induced hydrophilicity of mesoporous TiO₂ thin films coated on aluminum substrate

Mesoporous TiO₂ thin films were prepared on aluminum substrate via the reverse micellar method (RM-TiO₂) and sol-gel method (SG-TiO₂), respectively. It was found that the mesoporous RM-TiO₂ thin films exhibited a better photocatalytic performance than that of SG-TiO₂ in the degradation of acetone in air and photo-induced hydrophilicity. This was attributed to the fact that the RM-TiO₂ thin films had higher specific surface area and porosity than that of SG-TiO₂. The larger surface-to-volume ratio of mesoporous RM-TiO₂ thin films can serve as a more efficient transport path for gaseous reactants and products in photocatalytic reactions, thus improving the photocatalytic activity. The photocatalytic performance and hydrophilicity of RM-TiO₂ thin films coated on different substrates were also compared. The aluminium-supported samples showed a slower photocatalytic rate than those on quartz and stainless steel in the degradation of acetone because aluminum ions diffused from the substrate and acted as a charge recombination center. However, the hydrophilic property of the TiO₂/Al sample was superior to those on quartz and stainless steel substrates, probably due to its higher surface roughness and hydroxyl content. Copyright © 2006 Elsevier B.V. All rights reserved.