AVS 52nd International Symposium
    Surface Science Monday Sessions
       Session SS-MoP

Paper SS-MoP18
Adsorption and Reaction of CO and CO2 on Oxidized and Reduced SrTiO3(100) Surfaces

Monday, October 31, 2005, 5:00 pm, Room Exhibit Hall C&D

Session: Surface Science Poster Session
Presenter: L. Wang, Pacific Northwest National Laboratory
Authors: L. Wang, Pacific Northwest National Laboratory
S. Azad, Rice University
M.H. Engelhard, Pacific Northwest National Laboratory
Correspondent: Click to Email
The adsorption and reaction of CO and CO2 on oxidized and reduced SrTiO3(100) surfaces have been studied using temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy (XPS). XPS results indicate that the oxidized SrTiO3(100) surfaces are nearly defect-free with predominantly Ti4+ ions whereas the sputter-reduced surfaces contain substantial amounts of defects. Both CO and CO2 are found to adsorb weakly on the oxidized SrTiO3(100) surfaces. The desorption activation energies of CO and CO2 from the oxidized SrTiO3(100) surfaces are 38 and 32 kJmol-1, respectively, following adsorption at 110 K. On sputter-reduced surfaces, enhanced reactivity of CO and CO2 is observed due to the presence of oxygen vacancy sites that are responsible for dissociative adsorption of these molecules. Our studies indicate that CO and CO2 molecules exhibit relatively weaker binding to SrTiO3(100) compared with TiO2(110) and TiO2(100) surfaces. These differences can be attributed primarily to the influence of the Sr cations on the electronic structure of the Ti cations in the mixed oxide of SrTiO3.