AVS 49th International Symposium
    Surface Science Tuesday Sessions
       Session SS3-TuM

Paper SS3-TuM11
Interactions of Oxygenated Hydrocarbons with Stoichiometric and Defective SrTiO@sub3@(100) Surfaces: Role of Surface Structures and Defects

Tuesday, November 5, 2002, 11:40 am, Room C-112C

Session: Metals, Adsorbates, and Defects on TiO@sub 2@
Presenter: L.-Q. Wang, Pacific Northwest National Laboratory
Authors: L.-Q. Wang, Pacific Northwest National Laboratory
S. Azad, Pacific Northwest National Laboratory
K.F. Ferris, Pacific Northwest National Laboratory
M.H. Engelhard, Pacific Northwest National Laboratory
Correspondent: Click to Email
Molecular interactions on metal oxide surfaces are influenced by the surface structures and by the presence of surface defets. Adsorption and reactivity of oxygenated hydrocarbons on metal oxide surfaces have recently received considerable attention due t o the environmental concerns. In this study, we examined the interactions of a series of oxygenated hydrocarbons with stoichiometric and defective SrTiO@sub3@(100) surfaces using x-ray photoelectron spectroscopy (XPS), temperature programmed desorption (TPD), and electronic structure calculations. The goal of this study is to have a fundamental understanding of the role of surface structures and defects on the adsorption and reactivity of these oxygenated hydrocarbons on metal oxide surfaces. SrTiO@sub3@(100) was chosen as our model surface not only because of its heterogeneous and photo-catalytic activities but also because investigation of oxygenated hydrocarbons on single crystal oxide surfaces is very rare. This presentation compares the interaction o f acetaldehyde with that of methanol, ethanol and formic acid on the same surface. Since aldehydes are weaker than carboxylic acids and stronger than alcohols, the comparison of their reactivity on the surface is very interesting. It was found that methan ol, ethanol and acetaldehyde adsorb molecularly whereas formic acid goes through dissociative adsorption on stoichiometric SrTiO@sub3@(100) surface. As comparable with studies on other oxides such as TiO@sub2@, adsorption and protonation of weaker acids s uch as methanol, ethanol and acetaldehyde are found to depend more on the surface structures than stronger acids such as formic acid and these results are in good agreement with our theoretical calculations. However, decomposition and redox reactions of methanol, ethanol, and acetaldehyde take place when surface defects are created by Ar@super+@ sputtering. In addition, such surface defects change the reaction pathway for formic acid.