387319 Establishing the Connection Between the Geometric and Electronic Structure of Oxygen Species on Ag Surfaces: First-Principles DFT and Monte Carlo Studies

Wednesday, November 19, 2014
Galleria Exhibit Hall (Hilton Atlanta)
Matthew Morabito1, Hongliang Xin2 and Suljo Linic1, (1)Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, (2)Department of Chemical Engineering, Stanford University, Stanford, CA

Surface adsorbed species differentiated by local geometric and electronic structures often have distinct reactivity toward chemical transformations. It has been shown that during partial oxidation of ethylene electrophilic oxygen species on silver are responsible for the formation of ethylene oxide while the nucleophilic oxygen primarily leads to total combustion.[1] Although much work has been done on identifying the electronic fingerprint of surface adsorbed species, the link between geometric and electronic structure of these species is still lacking.[2]

Our objective is to establish the connection between the geometric and electronic structure of oxygen species on Ag surfaces (flat or stepped) under relevant catalytic conditions. We have employed an atomistic thermodynamics approach and Monte Carlo simulations to extend the results of DFT calculations to relevant catalytic conditions (T, P). To ensure complete sampling of the large space of possible surface configurations we have used the cluster expansion method to systematically coarse-grain the DFT-calculated energies.[3] The electronic structure (e.g., core-level shift) of oxygen species has been probed using density functional theory (DFT) calculations.[4]

[1]         R. B. Grant and R. M. Lambert, “A single crystal study of the silver-catalysed selective oxidation and total oxidation of ethylene,” J. Catal., vol. 92, no. 2, pp. 364–375, Apr. 1985.

[2]         T. C. R. Rocha, A. Oestereich, D. V Demidov, M. Hävecker, S. Zafeiratos, G. Weinberg, V. I. Bukhtiyarov, A. Knop-Gericke, and R. Schlögl, “The silver-oxygen system in catalysis: new insights by near ambient pressure X-ray photoelectron spectroscopy.,” Phys. Chem. Chem. Phys., vol. 14, no. 13, pp. 4554–64, Apr. 2012.

[3]         A. Walle and G. Ceder, “Automating first-principles phase diagram calculations,” J. Phase Equilibria, vol. 23, no. 4, pp. 348–359, Aug. 2002.

[4]         A. Nilsson and L. G. M. Pettersson, “Chemical bonding on surfaces probed by X-ray emission spectroscopy and density functional theory,” Surf. Sci. Rep., vol. 55, no. 2–5, pp. 49–167, Oct. 2004.

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