用原位液体池透射电镜技术表征金属钯在球形金纳米颗粒表面的异质沉积
发布时间：2018-11-10 16:47
【摘要】：采用原位液体池透射电镜技术,在扫描透射电子显微镜(STEM)中,实时观察溶液中金属钯(Pd)在金(Au)纳米颗粒及团簇周围的异质沉积过程。通过对该动态过程的定量分析,结合高分辨透射电子显微镜(HRTEM)对样品进行形貌与结构表征,研究异质沉积的机理。结果表明,电子束辐照下Au-Pd异质结构纳米颗粒的形成存在两种主要机制:第一种机制中,Pd在Au纳米颗粒表面的生长是以岛状沉积开始,随着时间推移,出现Pd岛的结构弛豫和沿着Au颗粒表面的迁移扩展。伴随Pd的不断沉积和弛豫,Au-Pd复合颗粒的外接圆直径表现为震荡生长,而Au表面的Pd覆盖率显示出随时间单调增加的趋势。第二种机制中,由于Pd单体在Au纳米颗粒上的沉积位点有限,使部分被还原的Pd在Au颗粒以外区域进行同质形核与生长形成Pd团簇,之后再与Au颗粒上的Pd岛合并。进一步的结果分析显示,Au颗粒外围的Pd沉积体为多晶结构,由随机取向的Pd纳米晶粒构成。
[Abstract]:In situ liquid cell transmission electron microscopy (TEM) technique was used to observe the heterogeneous deposition of palladium (Pd) in solution around gold (Au) nanoparticles and clusters by scanning transmission electron microscopy (STEM). The mechanism of heterogeneous deposition was studied by quantitative analysis of the dynamic process and characterization of the morphology and structure of the samples by high resolution transmission electron microscope (HRTEM). The results show that there are two main mechanisms for the formation of Au-Pd heterostructure nanoparticles under electron beam irradiation. In the first mechanism, the growth of Pd on the surface of Au nanoparticles begins with island deposition. Structural relaxation of Pd island and migration and propagation along the surface of Au particles occur. With the continuous deposition and relaxation of Pd, the diameter of the outer circle of Au-Pd composite particles appears to be oscillating, while the Pd coverage of Au surface shows a monotone increasing trend with time. In the second mechanism, due to the limited deposition sites of Pd monomers on Au nanoparticles, partial reduced Pd nucleates and grows into Pd clusters outside Au particles, and then merges with Pd islands on Au particles. The further analysis shows that the Pd deposition in the periphery of Au particles is polycrystalline and consists of randomly oriented Pd nanocrystals.
【作者单位】： 华东理工大学材料科学与工程学院超细材料制备与应用教育部重点实验室上海市先进聚合物材料重点实验室;浙江大学材料科学与工程学院硅材料国家重点实验室;中国科学院上海微系统与信息技术研究所信息功能材料国家重点实验室;
【基金】：上海市重点学科项目(B502) 上海市重点实验室项目(08DZ2230500) 上海市科学技术委员会项目(11nm0507000) 信息功能材料国家重点实验室开放课题(SKL201306) 国家自然科学基金(51222202)资助~~
【分类号】：O614.823;O647
本文编号：2323003
[Abstract]:In situ liquid cell transmission electron microscopy (TEM) technique was used to observe the heterogeneous deposition of palladium (Pd) in solution around gold (Au) nanoparticles and clusters by scanning transmission electron microscopy (STEM). The mechanism of heterogeneous deposition was studied by quantitative analysis of the dynamic process and characterization of the morphology and structure of the samples by high resolution transmission electron microscope (HRTEM). The results show that there are two main mechanisms for the formation of Au-Pd heterostructure nanoparticles under electron beam irradiation. In the first mechanism, the growth of Pd on the surface of Au nanoparticles begins with island deposition. Structural relaxation of Pd island and migration and propagation along the surface of Au particles occur. With the continuous deposition and relaxation of Pd, the diameter of the outer circle of Au-Pd composite particles appears to be oscillating, while the Pd coverage of Au surface shows a monotone increasing trend with time. In the second mechanism, due to the limited deposition sites of Pd monomers on Au nanoparticles, partial reduced Pd nucleates and grows into Pd clusters outside Au particles, and then merges with Pd islands on Au particles. The further analysis shows that the Pd deposition in the periphery of Au particles is polycrystalline and consists of randomly oriented Pd nanocrystals.
【作者单位】： 华东理工大学材料科学与工程学院超细材料制备与应用教育部重点实验室上海市先进聚合物材料重点实验室;浙江大学材料科学与工程学院硅材料国家重点实验室;中国科学院上海微系统与信息技术研究所信息功能材料国家重点实验室;
【基金】：上海市重点学科项目(B502) 上海市重点实验室项目(08DZ2230500) 上海市科学技术委员会项目(11nm0507000) 信息功能材料国家重点实验室开放课题(SKL201306) 国家自然科学基金(51222202)资助~~
【分类号】：O614.823;O647
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