Preparation of TiO 2 film by the MOCVD method and analysis for decomposition of trichloroethylene using in situ FT-IR spectroscopy

Abstract

MOCVD (molecular organic chemical vapor deposition) method was demonstrated in this study to prepare TiO 2 thin film of anatase structure with high photo-activity. From the results of characterization of XRD and SEM spectroscopy, it was identified that a TiO 2 thin film exhibited pure anatase structure and it was stably attached on a substrate. To investigate the photo-catalytic performance of the TiO 2 film, the trichloroethylene (TCE) decomposition was done. The conversion of TCE remarkably increased over the TiO 2 film synthesized by CVD method compared with that of TiO 2 film prepared by Degussa P-25 colloidal solution, in particular, the conversion over TiO 2 film synthesized by the CVD method reached above 90% after 120 min, otherwise, it was 85% over Degussa P-25 film. On the other hand, the intermediates produced from TCE decomposition were investigated by in situ method using a FT-IR spectroscopy. As a result, it was confirmed that TCE was transferred into dichloroacetylchloride (DCAC) and trichloromethane (CHCl 3) in transition state, and then, finally, it turned to CO 2, HCl, and H 2O. In addition, the addition of H 2O enhanced TCE decomposition. However, it was not affected to mechanism of TCE photo-catalytic decomposition.