Rational sidewall functionalization and purification of single-walled carbon nanotubes by solution-phase ozonolysis

A dispersion of raw HiPco single-walled carbon nanotubes in methanol has been subjected to ozonolysis at -78 °C, followed by treatment with various reagents, in independent runs, to generate a higher proportion of carboxylic acid/ester, ketone/aldhehyde, and alcohol groups, respectively, on the nanotube surface. This protocol has been found to purify nanotubes by removing amorphous carbon and metal impurities. More importantly, as had been theoretically predicted, the reaction sequence has been found to ozonize (and hence, oxygenate) the sidewalls of these nanotubes, thereby broadening the chemical processability and reactivity of these nanomaterials. The derivatized materials have been characterized by means of SEM and TEM, and spectroscopically, using Raman, UV-vis-near-IR, and X-ray photoelectron spectroscopies.