Dresden 2006 – wissenschaftliches Programm
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O: Oberflächenphysik
O 28: Surface reactions II
O 28.8: Vortrag
Dienstag, 28. März 2006, 17:30–17:45, WIL C207
Formation and Activity of Partially Oxidized Pd Nanoparticles — •Tobias Schalow1, Björn Brandt1, Mathias Laurin1, Sebastien Guimond1, Helmut Kuhlenbeck1, David E. Starr1, Shamil K. Shaikhutdinov1, Swetlana Schauermann1, Jörg Libuda2, and Hans-Joachim Freund1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Department of Chemical Physics, Faradayweg 4-6, 14195 Berlin, Germany — 2Friedrich-Alexander-Universität Erlangen-Nürnberg, Lehrstuhl für Physikalische Chemie II, Egerlandstrasse 3, 91058 Erlangen, Germany
The formation and reactivity of different oxygen species formed on iron-oxide supported Pd nanoparticles are studied by combing well-defined model catalysts, molecular beam experiments and various surface science techniques. It is shown that at temperatures above 500 K, large amounts of oxygen can be stored in form of a thin Pd oxide layer at the particle support interface, which can be reversibly accumulated and depleted. The formation of this interface oxide layer, however, shows a strong particle size dependence: While for small particles the oxygen storage capacity is limited by the amount of metal available, for large particles strong kinetic hindrances and a limited amount of accessible interface sites inhibit the oxygen storage process. Consequently, a pronounced maximum in oxygen storage capacity is found for particles of about 7 nm in diameter. Furthermore it is demonstrated how the formation and reduction of this interface oxide layer affects the activity of the catalyst towards CO oxidation under reaction conditions.