AVS 52nd International Symposium
    Surface Science Tuesday Sessions
       Session SS2-TuM

Paper SS2-TuM9
Controlling Surface Reactivity of SnO@sub 2@(101): Dissociative and Molecular Water Adsorption

Tuesday, November 1, 2005, 11:00 am, Room 203

Session: Defects on Oxide Surfaces
Presenter: M. Batzill, Tulane University
Authors: M. Batzill, Tulane University
U. Diebold, Tulane University
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Water adsorbs dissociatively on many oxide surfaces. In such cases undercoordinated surface oxygen atoms accept a proton and the remaining water-OH- adsorbs on surface cation sites. Thus the surface reactivity towards water dissociation may be tuned by controlling the number of undercoordinated surface oxygen atoms (Broensted base sites). On SnO@sub 2@(101) such a control over the surface composition can be exerted and the surface can be prepared with and without terminating oxygen atoms.@footnote 1@ Here we show by valence band photoemission that these two surfaces show different activity towards water adsorption. Surfaces without bridging oxygen adsorb water weakly while dissociation is observed on surfaces exhibiting terminating oxygen. The different activity of the surfaces is also apparent from water induced band bending. Dissociative adsorption causes downward band bending of ~0.35 eV which consequently causes a large increase in the surface conductivity of the SnO@sub 2@ sample. The latter is measured using a novel approach utilizing surface charging as a conductivity probe. @FootnoteText@ @footnote 1@ M. Batzill, A.M. Chaka, U. Diebold, Europhys. Lett. 65, 61 (2004).