Effect of mild nitric acid oxidation on dispersability, size, and structure of single-walled carbon nanotubes
Effect of mild nitric acid oxidation on dispersability, size, and structure of single-walled carbon nanotubes
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DOI：
10.1021/cm0717581
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发表时间：
2007-11-13
影响因子：
8.6
通讯作者：
Arepalli, Sivaram
中科院分区：
文献类型：
--
作者：
Tchoul, Maxim N.;Ford, Warren T.;Arepalli, Sivaram
单壁碳纳米管(SWNTs)被硝酸氧化后，在水、甲醇和N，N-二甲基甲酰胺中的分散性增加。用CoMoCat、HIPCO和脉冲激光汽化(PLV)方法制备的单壁碳纳米管研究了两种氧化方案，即在40℃下8M HNO3中超声波作用和2.6M HNO3中回流作用。超声作用1h和回流2-4h后，所有类型纳米管的分散性均有显著提高。较长时间的处理对分散性的进一步改善作用不大，回流时会使单壁碳纳米管降解。在不使用表面活性剂或聚合物的情况下，CoMoCat单壁碳纳米管在DMF中得到了稳定的分散，其浓度高达0.4g/L。拉曼光谱显示，回流过程使单壁碳纳米管具有更大的共价功能化！通过超音速程序。在分散性提高的同时，氧化导致了更小的直径和更短的长度，从AFM图像可以看出，大部分是成束的，而不是单个的管子。氧化后的单壁碳纳米管长度按PLV>；HIPCO>；CoMoCat顺序递减。对各种类型的单壁碳纳米管的调节方法的建议取决于它们的预期用途。
Oxidation of single-walled carbon nanotubes, (SWNTs) with nitric acid increases their dispersability in water, methanol, and N,N-dimethylformamide. Two oxidation protocols, sonication in 8 M HNO3 at 40 degrees C and reflux in 2.6 M HNO3, have been examined using SWNTs produced by the CoMoCat, HiPco, and pulsed laser vaporization (PLV) methods. The dispersability of all types of nanotubes increased substantially after I h of sonication and after 2-4 h of reflux. Longer treatments resulted in little further improvement in dispersability and at reflux degraded the SWNTs. Stable dispersions of CoMoCat SWNTs in DMF at concentrations as high as 0.4 g/L were achieved without the use of surfactants or polymers. Raman spectroscopy showed greater covalent functionalization of the SWNTs by the reflux procedure that! by the sonication procedure. Concurrent with improved dispersability, oxidation resulted in smaller diameters and shorter lengths as determined from AFM images, which show mostly bundles rather than individual tubes. The lengths of SWNTs after oxidation decreased in the order PLV > HiPco > CoMoCat. Recommendations for the method of conditioning of the various types of SWNTs depend on their intended use.