AVS 53rd International Symposium
    Surface Science Wednesday Sessions
       Session SS1-WeM

Invited Paper SS1-WeM9
'Live' Observations of Working Catalysts with STM and X-rays at High Pressures

Wednesday, November 15, 2006, 10:40 am, Room 2002

Session: Reactions on Metal & Bimetallic Surfaces
Presenter: J.W.M. Frenken, Leiden University, The Netherlands
Authors: J.W.M. Frenken, Leiden University, The Netherlands
B.L.M. Hendriksen, Lawrence Berkeley National Laboratory
S.C. Bobaru, Leiden University, The Netherlands
M.D. Ackermann, Leiden University, The Netherlands
Correspondent: Click to Email
We employ scanning tunneling microscopy (STM) and surface X-ray diffraction (SXRD) to obtain direct information on the structure and the atomic and molecular processes that occur on the surface of a catalyst while it is active in a chemical reaction under the high-temperatures and high-pressures conditions typical in catalysis. STM-movies obtained during the oxidation of CO on Pt and Pd surfaces, demonstrate that at high O@sub 2@ pressures the surface oxidizes and the reaction changes from a Langmuir-Hinshelwood to a Mars-Van-Krevelen mechanism.@footnote 1,2@ We resolve various ultrathin oxide structures, which only appear under high partial pressures of oxygen.@footnote 3@ Finally, we introduce a new explanation for self-sustained oscillations in the reaction rate@footnote 2@, which involves a novel role for atomic steps in catalysis.@footnote 4@ @FootnoteText@ @footnote 1@ B.L.M. Hendriksen and J.W.M. Frenken, Phys.Rev.Lett. 89, 046101 (2002).@footnote 2@ B.L.M. Hendriksen et al., Surf.Sci. 552, 229 (2004).@footnote 3@ M.D. Ackermann et al., Phys.Rev.Lett. 95, 255505 (2005).@footnote 4@ B.L.M. Hendriksen et al., to be published. .