Regensburg 2013 – scientific programme
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O: Fachverband Oberflächenphysik
O 78: Surface Dynamics I
O 78.3: Talk
Thursday, March 14, 2013, 16:30–16:45, H42
Non-adiabatic vibrational damping of O2 on Ag(100): implications for light-enhanced heterogeneous catalysis? — •Simon P. Rittmeyer, Jörg Meyer, and Karsten Reuter — Technische Universität München, Germany
The dissociation of oxygen molecules is the rate limiting step in various surface catalyzed oxidation reactions like e.g. the industrially important epoxidation of ethylene. To this end, Linic and coworkers reported a remarkable improvement of the energy efficiency of cubic silver nano-catalysts upon irradiation with visible light, and attributed this to a selective enhancement of the O2 dissociation step [1]. In their explanation, the non-adiabatic damping of the O-O stretch vibration of adsorbed O2 plays a crucial role. As going beyond the Born-Oppenheimer approximation for the description of metal-adsorbate interactions is still an emerging field of first-principles based modeling, we will subject the latter to a perturbative treatment rooted in time-dependent density-functional theory, extending an ansatz originally developed to obtain electron-hole pair excitation spectra during adsorption processes (see e.g. [2] and references therein). Within this new approach, we will present estimates for the vibrational lifetime of O2 adsorbed at various stable sites of the Ag(100) surface and critically discuss the implications for the model proposed by Linic and coworkers.
[1] P. Christopher, H. Xin, and S. Linic, Nature Chem. 3, 467 (2011).
[2] J. Meyer and K. Reuter, New J. Phys. 13, 085010 (2011).