Advanced sorting of single-walled carbon nanotubes by nonlinear density-gradient ultracentrifugation
Advanced sorting of single-walled carbon nanotubes by nonlinear density-gradient ultracentrifugation
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DOI：
10.1038/nnano.2010.68
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发表时间：
2010-06-01
影响因子：
38.3
通讯作者：
Weisman, R. Bruce
中科院分区：
文献类型：
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作者：
Ghosh, Saunab;Bachilo, Sergei M.;Weisman, R. Bruce
现有的单壁碳纳米管生长方法可以产生具有一系列结构和电子特性的样品，但许多潜在的应用需要纯纳米管样品。密度梯度超离心最近已经出现作为一种技术，用于分选作为生长的单壁纳米管的混合物到其不同的（n，m）结构形式，但迄今为止，这种方法已被限制到样品中只含有少量的纳米管结构，并经常需要重复的密度梯度超离心处理。在这里，我们报告说，使用定制的非线性密度梯度可以显着提高密度梯度超离心分离。我们表明，高度多分散的单壁纳米管的样品生长的HiPco方法很容易在一个单一的步骤中进行分类，得到富含任何10个不同的（n，m）物种的馏分。此外，该方法的次要变体允许分离七种（n，m）物质的镜像异构体（对映异构体）。这种方法的优化是由仪器的发展，光谱图内的纳米管内容物未受干扰的离心管的帮助。
Existing methods for growing single-walled carbon nanotubes produce samples with a range of structures and electronic properties, but many potential applications require pure nanotube samples. Density-gradient ultracentrifugation has recently emerged as a technique for sorting as-grown mixtures of single-walled nanotubes into their distinct (n, m) structural forms, but to date this approach has been limited to samples containing only a small number of nanotube structures, and has often required repeated density-gradient ultracentrifugation processing. Here, we report that the use of tailored nonlinear density gradients can significantly improve density-gradient ultracentrifugation separations. We show that highly polydisperse samples of single-walled nanotubes grown by the HiPco method are readily sorted in a single step to give fractions enriched in any of ten different (n, m) species. Furthermore, minor variants of the method allow separation of the mirror-image isomers (enantiomers) of seven (n, m) species. Optimization of this approach was aided by the development of instrumentation that spectroscopically maps nanotube contents inside undisturbed centrifuge tubes.