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Diverse melting modes and structural collapse of hollow bimetallic core-shell nanoparticles: a perspective from molecular dynamics simulations.

Huang R, Shao GF, Zeng XM, Wen YH - Sci Rep (2014)

Bottom Line: However, since the interior surface provides facilitation for the premelting initiating at the core, the two-stage melting is also observed in hollow Au-core/Pt-shell nanoparticle, remarkably different from the solid one.Additionally, the existence of stacking faults in the hollow Pt-core/Au-shell nanoparticle distinctly lowers its melting point.This study could be of great importance to the design and development of novel nanocatalysts with both high activity and excellent stability.

View Article: PubMed Central - PubMed

Affiliation: Institute of Theoretical Physics and Astrophysics, Department of Physics, Xiamen University, Xiamen, 361005, China.

ABSTRACT
Introducing hollow structures into metallic nanoparticles has become a promising route to improve their catalytic performances. A fundamental understanding of thermal stability of these novel nanostructures is of significance for their syntheses and applications. In this article, molecular dynamics simulations have been employed to offer insights into the thermodynamic evolution of hollow bimetallic core-shell nanoparticles. Our investigation reveals that for hollow Pt-core/Au-shell nanoparticle, premelting originates at the exterior surface, and a typical two-stage melting behavior is exhibited, similar to the solid ones. However, since the interior surface provides facilitation for the premelting initiating at the core, the two-stage melting is also observed in hollow Au-core/Pt-shell nanoparticle, remarkably different from the solid one. Furthermore, the collapse of hollow structure is accompanied with the overall melting of the hollow Pt-core/Au-shell nanoparticle while it occurs prior to that of the hollow Au-core/Pt-shell nanoparticle and leads to the formation of a liquid-core/solid-shell structure, although both of them finally transform into a mixing alloy with Au-dominated surface. Additionally, the existence of stacking faults in the hollow Pt-core/Au-shell nanoparticle distinctly lowers its melting point. This study could be of great importance to the design and development of novel nanocatalysts with both high activity and excellent stability.

No MeSH data available.


Related in: MedlinePlus

Temperature dependence of potential energy (solid lines) and the corresponding heat capacities (dashed lines) of hollow monometallic and bimetallic NPs.
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f2: Temperature dependence of potential energy (solid lines) and the corresponding heat capacities (dashed lines) of hollow monometallic and bimetallic NPs.

Mentions: In a continuous heating process, the solid-liquid phase transition can be well demonstrated by the caloric curves, as seen in Figure 2. Note that the heat capacity was deduced according to the following equation26where U is potential energy, and Rgc = 8.314 J/(molK). For facilitating comparison, the results of hollow Au and Pt NPs are also illustrated in Figure 2.


Diverse melting modes and structural collapse of hollow bimetallic core-shell nanoparticles: a perspective from molecular dynamics simulations.

Huang R, Shao GF, Zeng XM, Wen YH - Sci Rep (2014)

Temperature dependence of potential energy (solid lines) and the corresponding heat capacities (dashed lines) of hollow monometallic and bimetallic NPs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4231328&req=5

f2: Temperature dependence of potential energy (solid lines) and the corresponding heat capacities (dashed lines) of hollow monometallic and bimetallic NPs.
Mentions: In a continuous heating process, the solid-liquid phase transition can be well demonstrated by the caloric curves, as seen in Figure 2. Note that the heat capacity was deduced according to the following equation26where U is potential energy, and Rgc = 8.314 J/(molK). For facilitating comparison, the results of hollow Au and Pt NPs are also illustrated in Figure 2.

Bottom Line: However, since the interior surface provides facilitation for the premelting initiating at the core, the two-stage melting is also observed in hollow Au-core/Pt-shell nanoparticle, remarkably different from the solid one.Additionally, the existence of stacking faults in the hollow Pt-core/Au-shell nanoparticle distinctly lowers its melting point.This study could be of great importance to the design and development of novel nanocatalysts with both high activity and excellent stability.

View Article: PubMed Central - PubMed

Affiliation: Institute of Theoretical Physics and Astrophysics, Department of Physics, Xiamen University, Xiamen, 361005, China.

ABSTRACT
Introducing hollow structures into metallic nanoparticles has become a promising route to improve their catalytic performances. A fundamental understanding of thermal stability of these novel nanostructures is of significance for their syntheses and applications. In this article, molecular dynamics simulations have been employed to offer insights into the thermodynamic evolution of hollow bimetallic core-shell nanoparticles. Our investigation reveals that for hollow Pt-core/Au-shell nanoparticle, premelting originates at the exterior surface, and a typical two-stage melting behavior is exhibited, similar to the solid ones. However, since the interior surface provides facilitation for the premelting initiating at the core, the two-stage melting is also observed in hollow Au-core/Pt-shell nanoparticle, remarkably different from the solid one. Furthermore, the collapse of hollow structure is accompanied with the overall melting of the hollow Pt-core/Au-shell nanoparticle while it occurs prior to that of the hollow Au-core/Pt-shell nanoparticle and leads to the formation of a liquid-core/solid-shell structure, although both of them finally transform into a mixing alloy with Au-dominated surface. Additionally, the existence of stacking faults in the hollow Pt-core/Au-shell nanoparticle distinctly lowers its melting point. This study could be of great importance to the design and development of novel nanocatalysts with both high activity and excellent stability.

No MeSH data available.


Related in: MedlinePlus