Nanoalloy composition-temperature phase diagram for catalyst design: Case study of Ag-Au

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2012-07-15
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Wang, Lin-Lin
Tan, Teck
Johnson, Duane
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Johnson, Duane
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Ames National Laboratory

Ames National Laboratory is a government-owned, contractor-operated national laboratory of the U.S. Department of Energy (DOE), operated by and located on the campus of Iowa State University in Ames, Iowa.

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Abstract

By coupling a cluster expansion with density functional theory (DFT) calculations, we determine the configurational thermodynamics (site preferences and occupations) for alloyed nanoparticles (NPs) as functions of composition (c) and temperature (T), exemplified using a 55-atom Ag-Au truncated cuboctahedron NP. The c−T phase diagram for site occupations gives detailed design information for alloyed NP, especially the thermodynamically stable active sites for catalysis and how they change with stoichiometry and processing temperature. Generally, Ag prefers core and Au prefers shell, agreeing with our universal core-shell preference assessed from DFT impurity segregation energies but with interesting multishell configurations having specific active sites.

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This article is from Phys. Rev. B 86, 03438 (2012), doi:10.1103/PhysRevB.86.035438. Posted with permisison.

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Sun Jan 01 00:00:00 UTC 2012
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