New Insights into the structure of Pd-Au nanoparticles as revealed by aberration-corrected STEM.
New Insights into the structure of Pd-Au nanoparticles as revealed by aberration-corrected STEM.
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DOI：
10.1016/j.jcrysgro.2011.04.026
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发表时间：
2011-06-15
影响因子：
1.8
通讯作者：
Jose-Yacaman M
中科院分区：
文献类型：
--
作者：
Deepak FL;Casillas-Garcia G;Esparza R;Barron H;Jose-Yacaman M
Au-Pd双金属纳米粒子在催化领域有着重要的应用。它们的催化性能与其结构、合金的形成和结构中组成的变化直接相关。一种标准的想法是，双金属纳米颗粒可以是合金结构，也可以是核壳结构。本课题组利用像差校正的高角环形暗场扫描电子显微镜(HAADF-STEM)研究了Pd-Au纳米粒子的结构和组成。我们以前报道过，该纳米粒子由均匀合金化的内核、富Au的中间层和富钯的外壳组成。这一结构比简单模型所能预测的要复杂得多。在这篇文章中，我们报告了对该系统的进一步研究，其中通过进行光谱分析和化学分析(STEM*-EDAX，STEM-EELS)，现在可以更好地识别和理解界面结构。除了三层核壳结构外，我们还能够在某些情况下观察到四层核壳结构。整个核壳结构不是刚性的，也确实存在Au-Pd的插层到其他层中。此外，我们已经能够定位纳米颗粒中存在的堆积故障。我们还解决了层之间的接口结构问题。利用纳米衍射仪，我们发现，与Au或Pd的体相结构相反，纳米颗粒的整体结构变成了hcp。
Bimetallic nanoparticles of Au-Pd find important applications in catalysis. Their catalytic performance is directly related to the structure, alloy formation and variation of composition in the structure. A standard idea is that bimetallic nanoparticles can be either an alloy or a core shell structure. Our group has investigated the structure and composition of Pd-Au nanoparticles by using aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). We reported previously that the nanoparticles are composed of an evenly alloyed inner core, an Au-rich intermediate layer, and a Pd-rich outer shell. The structure is more complicated than what simple models can predict. In this paper we report additional studies of this system wherein by carrying out spectral and chemical analysis (STEM*-EDAX, STEM-EELS) the interface structure can now be better identified and understood. Apart from the three-layered core-shell structures we have also been able to observe in some cases a four-layered core-shell structure as well. The entire core-shell structure is not rigid and there is indeed intercalation of Au-Pd into the other layers as well. In addition we have been able to locate stacking faults present in the nanoparticles. We also address the problem of the interface structure between the layers. By using nanodiffraction we have found that the whole structure of the nanoparticles becomes hcp in contrast to the bulk structure of Au or Pd.
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影响因子：
15
作者：
Ding, Yong;Fan, Fengru;Wang, Zhong Lin
通讯作者：
Wang, Zhong Lin
影响因子：
10.8
作者：
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通讯作者：
Jose-Yacaman, Miguel
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3.7
作者：
Perez-Tijerina, Eduardo;Mejia-Rosales, Sergio;Jose-Yacaman, Miguel
通讯作者：
Jose-Yacaman, Miguel