Purification and characterization of single-walled carbon nanotubes

Single-walled carbon nanotubes (SWNTs) were purified and cut into short length by the liquid phase oxidation using the typical oxidants such as HNO3, H2SO4 and their mixture. The SWNT-acid solutions were refluxed at high temperature, filtered on poly tetra-fluoro ethylene (PTFE) filter paper, rinsed with distilled water, and then dried at room temperature. In order to rind optimum purifying condition, acid solutions were made by mixing nitric / sulfuric acid by the different Volume ratio. The reaction lime was also varied from Ih to 6h. Through this method, purified SWNTs with the length of less than 2 mu m were successfully obtained, which Nas confirmed by scanning electron microscopy (SEM). From transmission electron microscopy (TEM) analysis, it was Verified that SWNTs were purified with little damage on surface and metal catalysts were efficiently removed when sulfuric acid was mixed, which was also confirmed by energy disperse spectrum analysis (EDS). Moreover, size distribution of the purified SWNTs was characterized with Field Flow-Fractionation (FFF) method.