Partial encapsulation of Pd particles by reduced ceria-zirconia

Direct observation of metal-oxide interfaces with atomic resolution can be achieved by cross-sectional high-resolution transmission electron microscopy (HRTEM). Using this approach to study the response of a model, single-crystal thin film automotive exhaust-gas catalyst, Pd particles supported on t...

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Bibliographic Details
Published in:Applied physics letters 2005-11, Vol.87 (20), p.201915-201915-3
Main Authors: Sun, H. P., Pan, X. P., Graham, G. W., Jen, H.-W., McCabe, R. W., Thevuthasan, S., Peden, C. H. F.
Format: Article
Language:English
Subjects:
CATALYSTS
CERIUM
ELECTRONS
ENCAPSULATION
ENERGY-LOSS SPECTROSCOPY
Environmental Molecular Sciences Laboratory
OXIDATION
OXIDES
OXYGEN
PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
RESOLUTION
STORAGE
STRONG INTERACTIONS
strong metal suport interaction, ceria-zirconia, Palladium, catalytic converters, oxygen storage materials
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
VALENCE
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Summary:Direct observation of metal-oxide interfaces with atomic resolution can be achieved by cross-sectional high-resolution transmission electron microscopy (HRTEM). Using this approach to study the response of a model, single-crystal thin film automotive exhaust-gas catalyst, Pd particles supported on the (111) ceria-zirconia (CZO) surface, to a redox cycle, we have found two distinct processes for the partial encapsulation of the Pd particles by the reduced CZO surface that depend on their relative crystallographic orientations. In the case of the preferred orientation found for Pd particles on CZO, Pd ( 111 ) [ 110 ] ∕ ∕ CZO ( 111 ) [ 110 ] , a flat and sharp metal/oxide interface was maintained upon reduction, while ceria-zirconia from the adjacent surface tended to accumulate on and around the Pd particle. In rare cases, Pd particles with other orientations tended to sink into the oxide support upon reduction. Possible mechanisms for these encapsulation processes are proposed.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.2132067