Enhancing Effect on Photocatalitic Activity of TiO2/Pt/Al2O3 and TiO2/Sn/Al2O3 Films on Anodically Oxidized Aluminum

Aluminum was anodized in a Na3PO4 solution, and then platinum and tin were electrodeposited into nano pores of anodic oxidation film in H2PtCl6 and SnSO4 solutions. Titanium (IV) oxide (TiO2) thin film was immobilized on electrolytically colored anodic oxide coating of aluminum. The photocatalytic activity of prepared films was analyzed for photolysis of the malachite green. In the results, the photocatalytic activity of Pt loaded TiO2 (TiO2/Pt/Al2O3) film was highest in all films, and the relation between the amount of metallic colloid and photocatalytic activity was confirmed. Photocatalytic activity improved with increase of the electrodeposition amount, and activity was highest when the amount of platinum was about 4.2× 10^-5 kg·m^-2. But photocatalytic activity began to decline when the amount of platinum exceeded 4.2× 10^-5 kg·m^-2 because the platinum had a recombination center and decreasing surface area by electrodeposition. The photocatalytic activity of Sn loaded TiO2 (TiO2/Sn/Al2O3) film didnʹt reach that of the TiO2/Pt/Al2O3 film. However, that indicated photocatalytic activity of about 1.6 times compared with TiO2/Al2O3 film. SnO2 manifested photocatalysis as well as TiO2 because it was confirmed that sintered tin was SnO2 in the results of XPS. Therefore, anodic oxidation film and electrolytically colored anodic oxide coating were effective substrates of photocatalytic films.