多尺度模拟环境电子显微镜下Pd纳米颗粒在N2气氛中构型

多尺度模拟环境电子显微镜下Pd纳米颗粒在N2气氛中构型

韩 宇，朱倍恩^*，高 嶷^*

(1. 中国科学院上海应用物理研究所，上海201800；2. 中国科学院大学，北京100049；3.中国科学院上海高等研究院，上海201210)

摘  要 金属纳米颗粒的形貌和结构特征对其催化性能有着显著的影响。近年来一系列原位电子显微镜实验表明金属纳米颗粒形貌在不同气氛条件下能够发生动力学重塑，如何准确并定量预测和模拟该种变化对于理解金属纳米颗粒在服役环境中的结构和性质至关重要。在本文中，作者利用自主发展的多尺度结构重塑模型，模拟了在N₂条件下，随温度和压强变化时Pd纳米颗粒的结构演化，结果表明在低压条件下，Pd纳米颗粒的形貌几乎不随温度的变化而变化，而在压强为10⁵Pa时，低温下Pd纳米颗粒的形貌表现为一种球状多面体构型，随着温度的升高，形貌朝着立方八面体过渡并趋于稳定，上述结果证明了惰性气体N₂具有改变金属纳米颗粒结构的能力，从而为使用氮气作为保护气体的化学反应提供了一定的理论指导。

关键词 Pd纳米颗粒；密度泛函理论；表面能；吸附；多尺度结构重塑模型

中图分类号： 文献标识码：A   doi:10.3969/j.issn.1000-6281.2021.03.002

Shape of Pd nanoparticles in N₂ conditions under multi-scale simulated environmental electron microscopy

HAN Yu^1，2，ZHU Bei-en^2，3*，GAO Yi^2，3*

(1. Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800；2. University of Chinese Academy of Sciences, Beijing 100049；3.Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210，China)

Abstract   The morphology and structural characteristics of metal nanoparticles have a significant impact on their catalytic performance. Recently, a series of in-situ experiments has shown that metal nanoparticles can undergo reversible structural reconstruction under different atmosphere conditions. How to predict and conduct simulation of such evolution precisely and quantitatively is crucial for understanding the structures and properties of metal nanoparticles in real reactive environments. In this work, we applied a multi-scale structure reconstruction model to simulate the equilibrium shape of Pd nanoparticles under N₂ conditions at different temperatures and pressures. The results indicate that the inert gas N₂ may change the structure of metal nanoparticles, which provides a certain theoretical guidance for chemical reactions with nitrogen as a protective gas.

Keywords  Pd nanoparticles；density functional theory；surface energy；adsorption；multi-scale structure reconstruction model

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