Preparation of titanium(IV) oxide film on a hard alumite substrate

TiO2 was deposited onto hard alumite (Al/Al2O3/TiO2) by alternating current electrolysis and precipitation in (NH4)2[TiO(C2O4)2] solution at various temperatures, where the hard alumite was prepared by the anodic oxidation of aluminum in sulfuric acid (Al/Al2O3). The TiO2 electrodeposition mainly occurred at temperatures lower than about 50 °C, while the TiO2 deposition due to TiO(C2O4)22− adsorption onto alumina predominantly occurred at temperatures higher than about 50 °C. The amount of deposited TiO2 increased with the increase in the deposition temperature, leading to high photocatalytic activity. The deposited TiO2 at 90 °C followed by heat-treatment at 550 °C had an anatase structure and showed a high photocatalytic activity for the decomposition of acetaldehyde even under fluorescent lamp illumination. The Al/Al2O3/TiO2 prepared at 50 °C was optimal for practical use, because of a relatively high activity and the sufficient adhesion strength between the TiO2 and the Al/Al2O3 substrate due to the presence of the deposited TiO2 in the pores of the alumina film.