AVS 53rd International Symposium
    Surface Science Thursday Sessions
       Session SS1-ThM

Paper SS1-ThM8
H@sub 2@O Dissociation and Proton Diffusion on TiO@sub 2@(110)

Thursday, November 16, 2006, 10:20 am, Room 2002

Session: Reactivity of Oxide Surfaces I
Presenter: Z. Zhang, University of Texas at Austin
Authors: Z. Zhang, University of Texas at Austin
O. Bondarchuk, University of Texas at Austin
J.M. White, University of Texas at Austin
B.D. Kay, Pacific Northwest National Laboratory
Z. Dohnálek, Pacific Northwest National Laboratory
Correspondent: Click to Email
Rutile TiO@sub 2@(110) is a leading model oxide surface for the investigation of defect-related surface chemistry. The TiO@sub 2@ - H@sub 2@O system is of particular interest for both fundamental and applied science. We employed in situ Scanning Tunneling Microscopy (STM) to examine the adsorption and dissociation of water on bridge-bonded oxygen vacancies (BBO@sub v@) of the TiO@sub 2@(110) surface. Provided the H@sub 2@O coverage (< 2.5%) is less than the BBOv concentration (~10%), atomically resolved images taken at room temperature before and after water dose confirm the titration of individual BBO@sub v@ by dissociative adsorption of H@sub 2@O. The products are two hydroxyl species, one positioned at the BBO@sub v@, denoted OH@sub v@, and the other, denoted OH@sub b@, formed by protonation at either of the two nearest-neighbor bridging oxygen atoms. The protons formed by water dissociation are observed to diffuse along the BBO row. Surprisingly, the probability of OH@sub b@ diffusion is ~10 times higher than that of OH@sub v@, demonstrating their inequality. The research described in this presentation was performed in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.