Enhancing effect on photocatalitic activity of TiO 2/Pt/Al 2O 3 and TiO 2/Sn/Al 2O 3 films on anodically oxidized aluminum

Abstract

Aluminum was anodized in a Na 3PO 4 solution, and then platinum and tin were electrodeposited into nano pores of anodic oxidation film in H 2PtCl 6, and SnSO 4 solutions. Titanium (IV) oxide (TiO 2) thin film was immobilized on electrolytically colored anodic oxide coating of aluminum. The photocatalytic activity of prepared films was analy/ed for photolysis of the malachite green. In the results, the photocatalytic activity of Pt loaded TiO 2 (TiO 2/Pt/Al 2O 3) 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 TiO 2 (TiO 2/Sn/Al 2O 3) film didn't reach that of the TiO 2/Pt/ Al 2O 3 film. However, that indicated photocatalytic activity of about 1.6 times compared with TiO 2/Al 2O 3 film. SnO: manifested photocatalysis as well as TiO 2 because it was confirmed that sintered tin was SnO 2 in the results of XPS. Therefore, anodic oxidation film and electrolytically colored anodic oxide coating were effective substrates of photocatalytic films. © 2006 The Japan Institute of Metals.