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O: Fachverband Oberflächenphysik

O 9: Surface Chemical Reactions and Heterogeneous Catalysis I

O 9.5: Vortrag

Montag, 31. März 2014, 11:30–11:45, PHY C 213

Complex surface structure determination through first-principles global geometry optimization: c(2 × 2)-RuO₂(100) — •Tongyu Wang, Dennis Palagin, Saskia Stegmaier, and Karsten Reuter — Technische Universität München, Germany

”Ruthenium” catalysts exhibit a remarkable change of CO oxidation activity with reactant pressure [1]. Current understanding rationalizes the high activity at near-ambient conditions with a change of oxidation state. The enigmatic deactivation observed under oxidizing conditions is in turn assigned to a microfacetting of (otherwise highly active) RuO₂(110) facets into an inactive c(2 × 2)-RuO₂(100) phase [2]. A detailed structural model of the latter phase would be an important step towards understanding (and possibly suppressing) the deactivation mechanism. Yet, despite detailed experimental characterization, such a model could not be established to date. To this end, we perform density-functional theory based global geometry optimization using a basin hopping approach. Combined within ab initio thermodynamics we assess the relative stabilities of the obtained structural candidates and discuss their properties in light of the existing experimental data. [1] H. Over, Chem. Rev. 112, 3356 (2012); [2] J. Assmann et al., Angew. Chem. Int. Ed. 44, 917 (2005).