Highly dispersed multi-walled carbon nanotubes in ethanol using potassium doping

We demonstrated the production of an effective dispersion of multi-walled carbon nanotubes (MWCNTs) in ethanol using potassium doping (pi-stacking interaction). The homogeneous dispersion of individual MWCNTs was achieved without any contamination or severe disruption at the end caps or periphery of the tubes. Potassium as a doping material, phenanthrene as a nonpolar molecule, and 1,2-dimethoxyethane as a dipole solvent were used for our experiment. From UV-visible spectroscopy and visual observation, it was found that the dispersibility of the MWCNTs in ethanol was about 14 mg/dm(3). High resolution transmission electron microscopy and Raman spectroscopy showed that disruption of the end caps of the tubes and severance along the tube axis were rarely found. The scanning electron microscopy and corresponding EDX results indicated that the key to the dispersion mechanism was the potassium doping, which is driven by pi-stacking complex formation. We suggest that the dispersion of the MWCNTs was influenced by the potassium doping, which caused the enlargement and separation of the entangled-MWCNT networks, and was not affected by defects or modification of the surface morphology. (C) 2005 Elsevier Ltd. All rights reserved.