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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

Phase diagram of the Pt-Pd system for different shapes. Different shapes at a size equal to 4 nm and at the bulk scale. The solid lines indicate the liquidus curves whereas the dashed lines indicate the solidus ones.
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Figure 3: Phase diagram of the Pt-Pd system for different shapes. Different shapes at a size equal to 4 nm and at the bulk scale. The solid lines indicate the liquidus curves whereas the dashed lines indicate the solidus ones.

Mentions: The phase diagram of the Pt-Pd alloy is plotted in Figure 3. We note that the lens shape of the phase diagram is conserved at the nanoscale; however, the lens width increases for the shapes characterized by a small melting enthalpy and melting temperature, i.e., exhibiting a strong shape effect. Moreover, the melting temperature increases with the concentration of Pt in agreement with Ref. [25].


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

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

Phase diagram of the Pt-Pd system for different shapes. Different shapes at a size equal to 4 nm and at the bulk scale. The solid lines indicate the liquidus curves whereas the dashed lines indicate the solidus ones.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Phase diagram of the Pt-Pd system for different shapes. Different shapes at a size equal to 4 nm and at the bulk scale. The solid lines indicate the liquidus curves whereas the dashed lines indicate the solidus ones.
Mentions: The phase diagram of the Pt-Pd alloy is plotted in Figure 3. We note that the lens shape of the phase diagram is conserved at the nanoscale; however, the lens width increases for the shapes characterized by a small melting enthalpy and melting temperature, i.e., exhibiting a strong shape effect. Moreover, the melting temperature increases with the concentration of Pt in agreement with Ref. [25].

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