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Size-dependent catalytic and melting properties of platinum-palladium nanoparticles.

Guisbiers G, Abudukelimu G, Hourlier D - Nanoscale Res Lett (2011)

Bottom Line: The melting temperature, melting enthalpy, and catalytic activation energy were found to decrease with size.The predictions were compared with the available experimental data in the literature.PACS: 65.80-g; 82.60.Qr; 64.75.Jk.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Mechanics, Materials and Civil Engineering, Catholic University of Louvain, 2 Place Sainte Barbe, 1348 Louvain-La-Neuve, Belgium. gregory.guisbiers@physics.org.

ABSTRACT
While nanocatalysis is a very active field, there have been very few studies in the size/shape-dependent catalytic properties of transition metals from a thermodynamical approach. Transition metal nanoparticles are very attractive due their high surface to volume ratio and their high surface energy. In particular, in this paper we focus on the Pt-Pd catalyst which is an important system in catalysis. The melting temperature, melting enthalpy, and catalytic activation energy were found to decrease with size. The face centered cubic crystal structure of platinum and palladium has been considered in the model. The shape stability has been discussed. The phase diagram of different polyhedral shapes has been plotted and the surface segregation has been considered. The model predicts a nanoparticle core rich in Pt surrounded by a layer enriched in Pd. The Pd segregation at the surface strongly modifies the catalytic activation energy compared to the non-segregated nanoparticle. The predictions were compared with the available experimental data in the literature. PACS: 65.80-g; 82.60.Qr; 64.75.Jk.

No MeSH data available.


Related in: MedlinePlus

Composition dependency of the catalytic activation energy for a spherical nanoparticle of Pt-Pd. Nanoparticle of Pt-Pd with a size equal to 4 nm.
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Figure 5: Composition dependency of the catalytic activation energy for a spherical nanoparticle of Pt-Pd. Nanoparticle of Pt-Pd with a size equal to 4 nm.

Mentions: where x represents the alloy composition. For a spherical Pt-Pd nanoparticle with a diameter equal to 4 nm, by combining Equations 5-8, Eca seems to evolve quadratically with the composition when the segregation is not considered; which is not the case when the segregation is considered (Figure 5). For the segregated Pt-Pd nanoparticle, a maximum in the catalytic activation energy is reached around 16% of Pt composition.


Size-dependent catalytic and melting properties of platinum-palladium nanoparticles.

Guisbiers G, Abudukelimu G, Hourlier D - Nanoscale Res Lett (2011)

Composition dependency of the catalytic activation energy for a spherical nanoparticle of Pt-Pd. Nanoparticle of Pt-Pd with a size equal to 4 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211490&req=5

Figure 5: Composition dependency of the catalytic activation energy for a spherical nanoparticle of Pt-Pd. Nanoparticle of Pt-Pd with a size equal to 4 nm.
Mentions: where x represents the alloy composition. For a spherical Pt-Pd nanoparticle with a diameter equal to 4 nm, by combining Equations 5-8, Eca seems to evolve quadratically with the composition when the segregation is not considered; which is not the case when the segregation is considered (Figure 5). For the segregated Pt-Pd nanoparticle, a maximum in the catalytic activation energy is reached around 16% of Pt composition.

Bottom Line: The melting temperature, melting enthalpy, and catalytic activation energy were found to decrease with size.The predictions were compared with the available experimental data in the literature.PACS: 65.80-g; 82.60.Qr; 64.75.Jk.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Mechanics, Materials and Civil Engineering, Catholic University of Louvain, 2 Place Sainte Barbe, 1348 Louvain-La-Neuve, Belgium. gregory.guisbiers@physics.org.

ABSTRACT
While nanocatalysis is a very active field, there have been very few studies in the size/shape-dependent catalytic properties of transition metals from a thermodynamical approach. Transition metal nanoparticles are very attractive due their high surface to volume ratio and their high surface energy. In particular, in this paper we focus on the Pt-Pd catalyst which is an important system in catalysis. The melting temperature, melting enthalpy, and catalytic activation energy were found to decrease with size. The face centered cubic crystal structure of platinum and palladium has been considered in the model. The shape stability has been discussed. The phase diagram of different polyhedral shapes has been plotted and the surface segregation has been considered. The model predicts a nanoparticle core rich in Pt surrounded by a layer enriched in Pd. The Pd segregation at the surface strongly modifies the catalytic activation energy compared to the non-segregated nanoparticle. The predictions were compared with the available experimental data in the literature. PACS: 65.80-g; 82.60.Qr; 64.75.Jk.

No MeSH data available.


Related in: MedlinePlus