Preparation of TiO2 film by the MOCVD method and analysis for decomposition of trichloroethylene using in situ FT-IR spectroscopy

MOCVD (molecular organic chemical vapor deposition) method was demonstrated in this study to prepare TiO2) 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,) thin film exhibited pure anatase structure and it was stably attached on a substrate. To investigate the photo-catalytic performance of the TiO2 film, the trichloroethylene (TCE) decomposition was done. The conversion of TCE remarkably increased over the TiO2 film synthesized by CVD method compared with that of TiO2 film prepared by Degussa P-25 colloidal solution, in particular, the conversion over TiO2 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 (CHCl3) in transition state, and then, finally, it turned to CO2, HCl, and H2O. In addition, the addition of H2O enhanced TCE decomposition. However, it was not affected to mechanism of TCE photo-catalytic decomposition. (C) 2002 Elsevier Science B.V. All rights reserved.