Metallic And Semiconducting Carbon Nanotube Density Gradient Separation Method

For the separation of metallic and semiconducting single-walled carbon nanotubes(SWCNTs), In this paper, the method of density gradient separation has been systematic investigated in gradient medium of sucrose .In this paper, the SWCNTs have been prepared with the catalyst of YNi2 alloy via arc discharge. We purify the SWCNTs with nitric acid reflux and surfactant, respectively, and the method of nitric acid reflux mainly involves the ultrasound, reflux, washing, grinding, roasting. The samples have been characterized by near infrared visible spectroscopy, Raman spectroscopy, thermal analysis, scanning electron microscopy and it is found that the higher pure SWCNTs can be obtained via nitrate and surfactant treatment. Furthermore the aspects of centrifugal force and centrifugation time have been initially discussed on purifying SWCNTs with surfactant, in order to optimize experimental conditions and increase the separation efficiency. The results show that the surfactant can not only purify SWCNTs, but also its solution of centrifugation can be used for separation of density gradient.To begin with we will provide a brief introduction on the current methods of the separation of metallic and semiconducting SWCNTs in the field of chemical, physics and biological. Also, the method of separation of carbon nanotubes(CNTs) with density gradient can be equipped to separate from SWCNTs of different electrical conductivity, both of the density gradient method and quantity of separation of CNTs are superior to the others. In addition, the influencing factors of method of density gradient separation and the samples of SWCNTs have been preliminary studied and characterized by visible- near infrared spectroscopy and Raman spectra, respectively. In different layers of solution in centrifuge tube, we have obtained metallic SWCNTs of the highest purity of 68.49% and semiconducting SWCNTs of the high purity up to 96.47%. The method of density gradient can not only be used to arrange SWCNTs by different electroconductibility, but also can be ordered to SWCNTs by the diameter, and allow be initially discussed.