Department of Chemical Engineering; Nanotechnology Institute, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada.
Langmuir. 2010 Jan 19;26(2):1221-5. doi: 10.1021/la902341w.
We report a simple method to prepare individual electric arc-produced single-walled carbon nanotubes (SWNTs) in aqueous solution on a large scale through three steps of processing: refluxing in concentrated HNO(3), low speed centrifugation, and high speed centrifugation. The bulk production (10 g of starting SWNTs) results in a concentration of 0.2 mg/mL individual SWNTs stably dispersed in DI-H(2)O without any external protection. The atomic force microscopy images show that the aqueous dispersion contained approximately 80% individual SWNTs with lengths ranging from 500 nm to 1 micrometer. It is found that the stable individual SWNT dispersion has an absolute zeta potential value of approximately 72 mV with a concentration of 0.05 mg/mL at pH 5. We believe that it is this high zeta potential resulting from an electrical double layer which produces the repulsion to overcome the van der Waals attraction thereby keeping the SWNTs individually dispersed. The free-standing film prepared from the individual SWNT dispersion exhibits a 4-probe electrical conductivity of approximately 2000 S/cm and a transmittance of 60% at 550 nm.
我们报告了一种简单的方法，通过三步处理过程，在水溶液中大规模制备单个电弧产生的单壁碳纳米管（SWNTs）：回流浓 HNO 3、低速离心和高速离心。批量生产（10 克起始 SWNTs）可得到浓度为 0.2mg/mL 的稳定分散在 DI-H 2 O 中的单个 SWNTs，无需任何外部保护。原子力显微镜图像显示，该水溶液分散体中大约有 80%的单壁碳纳米管，长度从 500nm 到 1 微米不等。研究发现，稳定的单壁碳纳米管分散体在 pH 值为 5 时，浓度为 0.05mg/mL 时具有约 72mV 的绝对 Zeta 电位值。我们认为，正是这种高 Zeta 电位产生的双电层排斥力克服了范德华吸引力，从而使 SWNTs 保持单个分散状态。由单个 SWNT 分散体制备的自由站立薄膜在 550nm 处具有约 2000S/cm 的 4 探针电导率和约 60%的透光率。
