Structure and photocatalytic performances of glass/SnO2/TiO2 interface composite film

Glass/SnO2/TiO2, one interfacial composite semiconductor film with high photocatalytic activity, was prepared by depositing anatase TiO2 film on rutile SnO2 film. AES depth profile analyses of the film photocatalyst testified the bilayer structure of the sample. The glass/SnO2/TiO2 film with appropriate thickness of TiO2 layer showed much higher photocatalytic activity in the case of formaldehyde photodegradation compared with glass/TiO2 film. The results could be explained by efficient interfacial charge separation via the process of electron transfer from TiO2 to SnO2. However, when the thickness of TiO2 layer was beyond some certain value, the photocatalytic activity of glass/SnO2/TiO2 film was nearly as same as glass/TiO2 film. The reverse glass/TiO2/SnO2 composite film did not show higher photocatalytic activity than glass/TiO2 film. This emphasized that the proper sequence for depositing individual semiconductor layer on glass substrate was important. A schematic mechanism of charge transfer was presented. (C) 2003 Elsevier B.V All rights reserved.