Adsorption and Reaction of CO and CO{sub 2} on Oxidized and Reduced SrTiO{sub 3} (100) Surfaces
The adsorption and reaction of CO and CO{sub 2} on oxidized and reduced SrTiO{sub 3}(100) surfaces have been studied using temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy (XPS). XPS results indicate that the fully oxidized and vacuum annealed SrTiO{sub 3}(100) surfaces are nearly defect-free with predominantly Ti{sup 4+} ions whereas the sputter-reduced surfaces contain substantial amounts of defects ({approx} 40% reduced Ti sites). Both CO and CO{sub 2} are found to adsorb weakly on the oxidized SrTiO{sub 3}(100) surfaces. The desorption activation energies of CO and CO{sub 2} from the oxidized SrTiO{sub 3}(100) surfaces are 38 and 32 kJmol{sup -1}, respectively, following adsorption at 110 K. On sputter-reduced surfaces, enhanced reactivity of CO and CO{sub 2} is observed due to the presence of oxygen vacancy sites, causing dissociative adsorption of these molecules. Our studies indicate that CO and CO{sub 2} molecules exhibit relatively weaker binding to SrTiO{sub 3}(100) compared with TiO{sub 2}(110) and TiO{sub 2}(100) surfaces. These differences in reactivity can be attributed primarily to the influence of the Sr cations on the electronic structure of the mixed oxide of SrTiO{sub 3}.
- Research Organization:
- Pacific Northwest National Lab., Richland, WA (US), Environmental Molecular Sciences Laboratory (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 15016515
- Report Number(s):
- PNNL-SA-42588; 1907; KC0201050; TRN: US200513%%565
- Journal Information:
- Journal of Physical Chemistry B, Vol. 109, Issue 20; Other Information: PBD: 26 May 2005
- Country of Publication:
- United States
- Language:
- English
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