Regensburg 2004 – wissenschaftliches Programm
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O: Oberflächenphysik
O 20: Oberflächenreaktionen I
O 20.1: Vortrag
Dienstag, 9. März 2004, 11:15–11:30, H45
Adsorption and Oxidation of NH3 on RuO2(110) — •Yuemin Wang, Ursula A. Paulus, Karl Jacobi, and Gerhard Ertl — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin
The epitaxially grown RuO2(110) surface was found to exhibit high catalytic activity for CO oxidation [1, 2]. In the present work the interaction of NH3 with the stoichiometric and O-enriched RuO2(110) surfaces, which the latter exposes a weakly bound atomic oxygen species on-top of the unsaturated Ru atom (Ru-cus), is studied using high-resolution electron energy-loss spectroscopy (HREELS) and thermal desorption spectroscopy (TDS). At the stoichiometric RuO2(110) surface we observed only the molecular adsorption of NH3 on Ru-cus at 85 K, whereas on the O-enriched surface NH3 oxidation occurs with annealing to higher temperature. The reaction products depend on the coverage of O-cus. At low O2 exposures (below 0.3 L) NH3 reacts with O-cus to give rise to N2 and H2O. With increasing oxygen exposure NO is produced and becomes the main product at saturation of O-cus. The formation of other N-containing species such as N2O and NO2 were not observed. Reaction mechanisms for NH3 oxidation will be discussed in detail. [1] C. Y. Fan, J. Wang, K. Jacobi, G. Ertl, J. Phys. Chem. B 106, 10058(2002). [2] J. Wang, C. Y. Fan, K. Jacobi, G. Ertl, Surf. Sci. 481, 113 (2001).