Molecular Dynamics Investigation on Thermal Stability and Shape Evolution of Pd-Au Heterostructured Nanorods: Implications for Catalysis,ACS Applied Nano Materials

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Molecular Dynamics Investigation on Thermal Stability and Shape Evolution of Pd-Au Heterostructured Nanorods: Implications for Catalysis
ACS Applied Nano Materials ( IF 5.3 ) Pub Date : 2021-09-28 , DOI: 10.1021/acsanm.1c02705
Tao Zhao ₁ , Lei Li ₁ , Rao Huang ₁ , Yu-Hua Wen ₁

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Heterogeneous nanostructures have attracted tremendous interest because of their exceptional properties and promising applications in extensive fields. In this work, we employed molecular dynamics (MD) simulations to investigate thermally driven structural and shape evolutions of Pd-Au heterostructured nanorods consisting of hexagonal close-packed (hcp) Pd-core/Au-shell structures in the middle and face-centered cubic (fcc) Au terminated at both ends (referred to as fcc-2H-fcc Pd@Au nanorods). Our results reveal that these nanorods exhibit a two-stage melting mode, that is, melting initiates at both ends of the nanorods and extends to the middle with increasing temperature. Moreover, specific thermodynamic behaviors are associated with the core size. With the lowering core size, the difference in the melting points between the core and the shell in the nanorods decreases accordingly, and the two-stage melting characteristic tends to be obscure. During heating, these nanorods experience a significant shrinkage after the melting of Au at both ends, forming a liquid-like shell/solid-core structure prior to the overall melting. However, two-stage melting is absent in fcc-2H-fcc Au nanorods. These results extend the fundamental understanding of the thermal stability of metallic heterostructured nanorods and provide a theoretical reference for the design and application of one-dimensional metallic heterostructures.

中文翻译：

Pd-Au 异质结构纳米棒热稳定性和形状演变的分子动力学研究：对催化的影响

异质纳米结构因其优异的性能和在广泛领域的应用前景而引起了极大的兴趣。在这项工作中，我们采用分子动力学 (MD) 模拟来研究 Pd-Au 异质结构纳米棒的热驱动结构和形状演变，该纳米棒由中间和面心的六边形密堆积 ( hcp ) Pd-核/Au-壳结构组成。立方 ( fcc ) Au 两端终止（简称fcc -2H- fccPd@Au 纳米棒）。我们的研究结果表明，这些纳米棒表现出两阶段熔化模式，即熔化从纳米棒的两端开始，并随着温度的升高延伸到中间。此外，特定的热力学行为与核心尺寸相关。随着核尺寸的减小，纳米棒中核壳之间的熔点差异相应减小，两段熔化特性趋于模糊。在加热过程中，这些纳米棒在两端 Au 熔化后发生显着收缩，在整体熔化之前形成液体状壳/实核结构。然而，在fcc -2H- fcc 中不存在两阶段熔化金纳米棒。这些结果扩展了对金属异质结构纳米棒热稳定性的基本认识，为一维金属异质结构的设计和应用提供了理论参考。

更新日期：2021-10-22

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