Purification of carbon single-wall nanotubes by potassium intercalation and exfoliation

A purification procedure for single-wall carbon nanotubes prepared by the arc-discharge method is described that employs a new step of potassium intercalation. Thermogravimetric analysis, Raman spectroscopy, X-ray diffraction, and transmission electron microscopy were used to characterize the results of each purification step. This potassium intercalation step is particularly useful for exfoliating the graphitic shell structure that typically surrounds the metal catalyst particles that remain from the nanotube synthesis. By exfoliating the shell structure, subsequent treatments are more efficacious for removing the metal catalyst particles. By testing full purification procedures, it is demonstrated that with potassium intercalation the number of purification steps can be reduced.