AVS 58th Annual International Symposium and Exhibition
    Surface Science Division Wednesday Sessions
       Session SS-WeA

Paper SS-WeA9
Adsorption and Photo-Reactivity of CO on TiO2(110)

Wednesday, November 2, 2011, 4:40 pm, Room 107

Session: Adsorption & Reactions on Oxide Surfaces
Presenter: Nikolay Petrik, Pacific Northwest National Laboratory
Authors: N.G. Petrik, Pacific Northwest National Laboratory
G.A. Kimmel, Pacific Northwest National Laboratory
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We have studied the low-temperature adsorption and reactions of CO on reduced, oxidized, hydroxylated, and electron-irradiated TiO2(110) using temperature programmed desorption, photon-stimulated desorption (PSD) and reflection-absorption infrared spectroscopy (RAIRS). Changing the condition of the crystal surface and the adsorbate coverage provides insight into the interactions of adsorbed CO with 5-fold coordinated Ti sites, (Ti5c), bridge-bonded oxygen (BBO) sites, and defect sites (oxygen vacancies, bridging hydroxyls and radiation-induced surface defects). Infrared spectra were obtained for light with the plane of incidence parallel and perpendicular to the [001] azimuths of TiO2(110). For adsorption on Ti5c sites, the RAIRS spectra are consistent with CO adsorbed nearly perpendicular to the surface. For adsorption on BBO sites, the molecules adsorb parallel to the surface and perpendicular to the rows of BBO atoms. The reactivity of various molecular adsorption forms of CO is probed using PSD. In CO photo-oxidation, the PSD yields of CO and CO2 change dramatically with initial CO coverage, indicating the importance of the relative position and orientation of O2 and CO molecules for the photochemical reaction.