Sorting carbon nanotubes by their diameter and number of walls

Double walled carbon nanotubes (DWNTs) were synthesized by chemical vapor deposition method using a metal mixture of cobalt and molybdenum, supported by titanium silicalite (TS-1). Ethanol was a carbon feeding source. After purifying steps, including oxidation in the air and treatment with NaOH and the major species of as-synthesized CNTs were DWNTs. Well dispersed CNT solutions were achieved using the surfactant sodium cholate. The density gradient separation method using ultracentrifugation was used to sort CNTs by their diameter and the number of sidewalls. UV-vis NIR, Raman, Photoluminescence (PL) and Transmittance electron microscopy (TEM) were studied to distinguish various diameter and different types of CNTs. These studies were used to demonstrate sorting of synthesized CNTs by their diameter and number of sidewalls.