Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 58: Surface chemical reactions II
O 58.10: Vortrag
Mittwoch, 24. März 2010, 17:15–17:30, H42
Structure-Sensitivity in Catalytic Reactions on Ir(210) Surfaces — •Payam Kaghazchi1, Wenhua Chen2, and Timo Jacob1 — 1Universität Ulm, Albert-Einstein-Allee 47, D-89069 Ulm, Germany — 2Rutgers University, NJ 08854, USA
The formation of facets on single-crystal surfaces provides a reproducible basis and model systems for studying catalytic reactions. In this context, recent experiments on the adsorption and decomposition of NO on O-covered planar and nano-faceted Ir(210) with variable facet sizes showed pronounced structure-sensitivity and an unexpectedly high reactivity for NO decomposition. Using density functional theory we studied the adsorption of NO, O, and (NO+O) on Ir(210), as well as on Ir(311) and Ir(110), the surfaces which are exposed after facet formation. In agreement with TPD and HREELS data, we find that NO adsorbs on atop sites of planar Ir(210) but on both bridge and atop sites of Ir(311) and (110) faces of faceted Ir(210) [1]. Coadsorption of O does not influence adsorption sites of NO but reduces the Ir–NO bond strength on Ir(210), Ir(110) and Ir(311). In contrast, coadsorption of NO (on O-covered Ir surfaces) indeed influences adsorption sites of O and reduces Ir-O bond strength on Ir(110) and Ir(311) significantly [2]. Our findings should be of importance for the development of Ir-based catalysts for NO decomposition under oxygen-rich conditions. [1] W. Chen, T. E. Madey, A. L. Stottlemyer, J. G. Chen, P. Kaghazchi, T. Jacob, J. Phys. Chem. C, 112, 19113, (2008), [2] W. Chen a, A. L. Stottlemyer, J. G. Chen, P. Kaghazchi, T. Jacob, T. E. Madey, R. A. Bartynski, Surf. Sci., 603, 3136, (2009).