Redox Sorting of Carbon Nanotubes
Redox Sorting of Carbon Nanotubes
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DOI：
10.1021/nl504189p
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发表时间：
2015-03-01
期刊：
影响因子：
10.8
通讯作者：
Zheng, Ming
中科院分区：
文献类型：
--
作者：
Gui, Hui;Streit, Jason K.;Zheng, Ming
这项工作扩大了单壁碳纳米管（SWCNT）的氧化还原化学研究其在一些SWCNT分选过程中的作用。使用聚乙二醇（PEG）/右旋糖酐（DX）水两相系统，我们表明，氧化还原分子和单壁碳纳米管之间的电子转移引发重组的表面活性剂涂层，导致强烈的调制纳米管分配在两个阶段。虽然氧化的SWCNT混合物更有利于DX相，但轻度还原的PEG相能够从氧化中回收SWCNT并从DX相中连续提取它们。值得注意的是，提取顺序如下单壁碳纳米管的带隙：较大的带隙的半导体纳米管的第一，其次是较小的带隙的半导体纳米管，然后小，但非零带隙的非扶手椅金属管，最后扶手椅金属纳米管的零带隙。此外，我们表明，氧化还原诱导的表面活性剂重组是一种常见的现象，影响纳米管的浮力在密度梯度场，亲和力的聚合物基质，和在有机溶剂中的溶解度。这些研究结果建立氧化还原调节表面活性剂涂层结构的一般机制，用于调整各种各样的单壁碳纳米管分选过程，并首次证明扶手椅和nonarmchair金属单壁碳纳米管可以通过其对氧化还原的差分响应来分离。
This work expands the redox chemistry of single-wall carbon nanotubes (SWCNTs) by investigating its role in a number of SWCNT sorting processes. Using a polyethylene glycol (PEG)/dextran (DX) aqueous two-phase system, we show that electron-transfer between redox molecules and SWCNTs triggers reorganization of the surfactant coating layer, leading to strong modulation of nanotube partition in the two phases. While the DX phase is thermodynamically more favored by an oxidized SWCNT mixture, the mildly reducing PEG phase is able to recover SWCNTs from oxidation and extract them successively from the DX phase. Remarkably, the extraction order follows SWCNT bandgap: semiconducting nanotubes of larger bandgap first, followed by semiconducting nanotubes of smaller bandgap, then nonarmchair metallic tubes of small but nonvanishing bandgap, and finally armchair metallic nanotubes of zero bandgap. Furthermore, we show that redox-induced surfactant reorganization is a common phenomenon, affecting nanotube buoyancy in a density gradient field, affinity to polymer matrices, and solubility in organic solvents. These findings establish redox modulation of surfactant coating structures as a general mechanism for tuning a diverse range of SWCNT sorting processes and demonstrate for the first time that armchair and nonarmchair metallic SWCNTs can be separated by their differential response to redox.