Relationship between the photocatalytic activity and crystallographic orientation of rutile TiO2 single crystals

Although photocatalytic activity of TiO2 is mainly discussed in terms of the band gap energy, the importance of surface oxygen for the decomposition of chemicals on the photocatalyst is emphasized in several reports. The availability and stability conditions of the surface oxygen atoms on TiO2 crystals depend on the surface orientation of the crystals. In this study, ruffle TiO2 single crystals with different orientations are used and we evaluate the progress of photocatalytic decomposition reactions by the weight loss of the salad oil and linoleic acid due to formation of gaseous species. If the surface of ruffle TiO2 single crystals is not reconstructed and surface oxygen is involved, the orientation of the surface affects the photocatalytic activity of TiO2; the photocatalytic activity increases in the order of (114) < (100) <(101) < (001). (C)2013 The Ceramic Society of Japan. All rights reserved.