Direct Imaging for Single Molecular Chain of Surfactant on CeO2 Nanocrystals
Direct Imaging for Single Molecular Chain of Surfactant on CeO2 Nanocrystals
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DOI：
10.1002/smll.201801093
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发表时间：
2018-08-02
期刊：
影响因子：
13.3
通讯作者：
Ikuhara, Yuichi
中科院分区：
文献类型：
--
作者：
Hao, Xiaodong;Chen, Chunlin;Ikuhara, Yuichi
有机表面活性剂通过吸附在纳米晶表面，控制纳米晶的大小和形貌，进而使其组装成有序的超结构，为实际应用提供多种功能纳米材料。为了提高对NCS表面化学的认识，直接将表面活性剂分子溶解在NCS表面是非常必要的。然而，对于单分子有机表面活性剂在NCS上的成像分辨率和对比度是不够的。本工作利用最先进的像差校正扫描电子显微镜(STEM)成像和电子能量损失谱(EELS)技术对有机表面活性剂在CeO2纳米碳管上的直接表征进行了研究。通过Eels元素图谱，在原子尺度上获得了有机表面活性剂在CeO2纳米管上存在和分布的明确证据。此外，系统地调整和优化了扫描电子显微镜成像参数，实现了有机表面活性剂单分子链在CeO2纳米管上的直接成像。这种有机表面活性剂分子在纳米碳管表面的直接可视化是纳米材料表面化学和材料表征领域的一大进步。
Organic surfactant controls the synthesis of nanocrystals (NCs) with uniform size and morphology by attaching on the surface of NCs and further facilitates their assembly into ordered superstructure, which produces versatile functional nanomaterials for practical applications. It is essential to directly resolve the surfactant molecules on the surface of NCs to improve the understanding of surface chemistry of NCs. However, the imaging resolution and contrast are insufficient for a single molecule of organic surfactant on NCs. In this work, direct characterization of organic surfactant on CeO2 NCs is conducted by using the state-of-the-art aberration corrected scanning transmission electron microscopy (STEM) imaging and electron energy loss spectra (EELS) techniques. The explicit evidence for the existence and distribution of organic surfactant on CeO2 NCs are obtained on the atomic scale by EELS elemental mapping. Besides, STEM imaging parameters are systematically adjusted and optimized for the direct imaging of a single molecular chain of organic surfactant on CeO2 NCs. Such direct visualization of organic surfactant molecule on the surface of NCs can be a significant step forward in the fields of nanomaterials surface chemistry and materials characterization.