Chemistry Department Seminar

"Nano-Scale Environmental Effects on the Reactivity of Platinum Clusters"

Presented by Ye Xu, Center for Nanophase Materials Sciences, Oak Ridge National Laboratory

Wednesday, March 11, 2009, 11:00 am — Room 300, Bldg. 555

Advances in synthesis techniques for size-defined metal clusters have brought uniform and potentially size-tunable nano-catalysts closer to reality. The versatility of platinum catalysts in many important industrial and energy applications and the high cost of the metal make Pt an excellent candidate for going “nano.” However, the response of such tiny objects to the chemical environment will need to be thoroughly understood before this type of novel catalyst can be productively deployed. The ability of theory and computational modeling to elucidate the properties of objects in the angstrom size regime makes it an ideal tool for nano-catalysis research. Therefore we have performed density functional theory calculations to explore the interaction of a series of small Pt clusters with prototypical environmental elements. Non-bulk-like, size-dependent phase behavior and accompanying changes in the molecular and electronic structures are identified for the isolated clusters when they are exposed to an oxygen atmosphere, and size- and composition-dependent reactivity is found for two model oxidation reactions, CO and NO oxidation. In addition, we have investigated how adsorption on a MgO(100) support surface affects the structures and oxidation of the Pt clusters and analyzed the mechanism of adhesion. Our results shed light on the intricate coupling between particle size, chemical environment, and reactivity in the surface chemistry of finite supported metal clusters.

Hosted by: Alex Harris

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