UV activity of titanium dioxide films and TiO2 embedded in ordered mesoporous SBA-15 structures for CO2 photo-reduction reactions

Deniz Uner ,  Ozlem Ozcan ,  Orcun Ergun ,  Osman Karslioglu ,  Aysen Yilmaz ,  Rasit Turan 

Middle East Technical University (METU), Inonu Bulvari, Ankara 06531, Turkey

Abstract

TiO2 films coated on hollow glass beads via a sol-gel procedure were tested for the photo reduction of CO2 in the gas phase. Pt was incorporated on the films either by adding the precursor salt in the sol, Pt(in), or by wet impregnation of calcined film with an aqueous solution of the precursor salt, Pt(on). TiO2 films could be prepared with thicknesses ranging from 300 nm to 3000 nm, measured by a surface DekTak profilometer. The synthesized samples were characterized by powder X-ray diffraction and Photo Luminescence spectroscopy. Under UV illumination, the methane yields of platinized TiO2 films decreased in the following order: Pt(on).TiO2>Pt(in).TiO2>TiO2. Photoluminescence spectroscopy indicated that the spectrum was blue shifted for Pt(in) catalysts, while no such shift was observed for Pt(on) catalysts. These results are interpreted in terms of charge separation effect of the external Pt. The band-gap modification as revealed by the photoluminescence spectroscopy indicated no effect on the photocatalytic activity of the films. In the second part of the study, titanium dioxide containing SBA-15 structures have been prepared by a sol-gel method using the self organizing polymer pluronic 123 and adding titanium(IV) isopropoxide into the solution in the preheating and precalcination stage. XRD pattern showed the SBA-15 characteristic peaks at 2q= 1.5 and 1.8 indicating long range order in the SiO2 framework.

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Presentation: Oral at E-MRS Fall Meeting 2006, Symposium B, by Deniz Uner
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-15 15:36
Revised:   2009-06-07 00:44
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