초록 |
TiO2 films in various thickness were prepared by MOCVD technique and sol-gel method, and their photocatalytic activities in the decomposition of gaseous 2-propanol were evaluated. We have found that the photocatalytic activity of TiO2 films are greatly dependent on film thickness and its surface roughness: The photocatalytic activity increases with the increase of film thickness, while it decreases with the increase of surface roughness. The surface of each film was characterized by SEM, AFM and XRD. We propose that the photogenerated electron/hole pairs in the inside of TiO2 surface are transferred to the film surface. We provided a model explaining this phenomena, and also carried out several experiments supporting this proposal. |