Berlin 2012 – scientific programme
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O: Fachverband Oberflächenphysik
O 67: Metal surfaces: Adsorption of H/O and inorganic molecules
O 67.5: Talk
Thursday, March 29, 2012, 11:30–11:45, MA 043
Structure and characterization of the hydrogen-bonded NH3-NO coadsorption on Pt(111): an ab-initio study. — •Andrea Cepellotti1, Angelo Peronio2, and Maria Peressi3 — 1Theory and Simulation of Materials, École Polytechnique Fédérale de Lausanne — 2IOM-CNR Laboratorio TASC, Trieste — 3Dipartimento di Fisica, Università di Trieste
The study of coadsorption states is an important subject in heterogeneous catalysis, since interactions between adsorbates can inhibit or allow specific reaction pathways. As such the coadsorption of NH3 and NO on Pt(111) is an interesting system that still lacks a satisfactory characterization both on theoretical and experimental grounds. Early EELS and TDS experiments [1] and recent STM measurements have suggested the formation of complexed structures composed by the two molecules.
Available observations are not able to unambiguously characterize the observed structures, therefore we employ density functional theory to demonstrate the existence of two stable structures, determining the geometrical structure by means of total energy minimization and reproducing the available experimental data. The electronic structure has been characterized, proving that the interaction between adsorbates arises from a hydrogen bond between each H and O. Such interaction suggests an explanation for the high selectivity of NH3 in the reduction with NO on platinum-based catalysts, which makes this class of systems suitable for combustion-gas treatment.
[1] J. L. Gland and B. A. Sexton, J. Catal. 68, 286 (1981)