中空结构Pt纳米粒子热稳定性和形变的分子动力学研究

不同于实心结构纳米粒子,中空结构Pt纳米粒子具有低密度、高孔隙率和大的比表面积等特点,具有特殊的物理化学性质,在催化、光电子和药物输送领域有重要的应用.纳米粒子热稳定性和形变特性对其合成、应用具有重要的影响.利用分子动力学模拟研究中空结构Pt纳米粒子结构稳定性和形变过程,对不同壳层厚度的Pt纳米粒子进行分析,结果表明:在弛豫过程,温度为0.1 K时,壳层厚度为0.5 nm的Pt纳米粒子结构将发生形变,壳层厚度为1 nm、1.5 nm、2.0 nm、2.5 nm和3 nm纳米粒子结构保持几乎不变;升温过程,中空结构Pt纳米粒子塌缩时对应的温度随着壳层厚度增加而升高;塌缩过程所经历的温度区间很窄,空心结构短时间内突变为实心结构,另外,中空结构纳米粒子塌缩后,内部原子重新排列,仍保持有序的fcc结构.

Thermal Stability and Structural Collapse of Hollow Pt Nanoparticles by Molecular Dynamics Simulations

Hollow Pt nanoparticles exhibit unusual chemical and physical characteristics different from their solid counterparts due to the advantages of low density, high porosity and large specific surface area, possessing important technological applications such as catalysis, optoelectronics, and drug delivery. The thermal stability and deformation are significance for their syntheses and applications. In this article, molecular dynamics simulations using the embedded-atom method have been employed to study the thermodynamic evolution of hollow Pt nanoparticles. Our investigation reveals that when the temperature is 0.1 K, the nanoparticle structure (the shell thickness is 0.5 nm) will deform while others (the shell thickness is 1 nm, 1.5 nm, 2.0 nm, 2.5 nm and 3 nm) remain almost unchanged during the relaxation process. The corresponding temperature of the collapse of the hollow nanoparticles increases with the increase of the shell thickness during the heating process. The temperature range required for the collapse process is very narrow and hollow structure can be transformed into solid structure in a short time. After the particles collapse, the internal atoms are rearranged and still maintain an orderly fcc structure.