IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Tuesday Sessions
       Session SS-TuA

Paper SS-TuA6
Surface Investigations of TiO@sub 2@ Anatase (101)

Tuesday, October 30, 2001, 3:40 pm, Room 121

Session: Metal Oxides: Structure and Photocatalysis
Presenter: N. Ruzycki, Tulane University
Authors: N. Ruzycki, Tulane University
D.L. Ederer, Tulane University
G.S. Herman, Pacific Northwest National Laboratory
M.A. Henderson, Pacific Northwest National Laboratory
U. Diebold, Tulane University
Correspondent: Click to Email
Titanium dioxide exists in three cyrstallographic structures, rutile, anatase, and brookite. The surfaces of rutile, especially the most stable (110) face, are very well investigated, but far less is know about the technologically much more relevant anatase phase. We report a study of the lowest-energy face, the (101) surface of an anatase mineral sample. After sputtering and annealing to a temperature of 650°C, a sharp (1x1)LEED pattern is observed. In STM the surface morphology is dominated by small triangularly-shaped terraces separated by monoatomic steps.@footnote 1@ The step directions are consistent with the ones expected from simple bond-counting rules. Surprisingly, very few point defects are observed with atomic-resolution STM images and HREELS. This is consistent with the low surface free energy predicted in first-principles calculations.@footnote 2@ It is in contrast to rutile (110), however, where a similar surface treatment creates a few percent of oxygen vacancies. These surface defects play a major role in the surface chemistry of rutile (110), for example, they promote the dissociation of water.@footnote 2@ Adsorption of water is used to probe the surface reactivity of anatase (101). Predominantly molecular adsorption is found, consistent with the picture that po int defects do not play a major role. @FootnoteText@@footnote 1@W. Hebenstreit, N. Ruzycki, G. S. Herman, and U. Diebold, Phys. Rev. B 64 (24) (2000) R16334. @footnote 2@A. Vittadini, A. Selloni, and M. Gratzel, Phys.Rev.Lett.. 81 (14) 2954. 3. M. A. Henderson, Surf. Sci. 335 (1996) 151.