Surface chemistry and pore structure of purified HiPco single-walled carbon nanotube aggregates

HiPco single-walled carbon nanotube (HCNT) containing about 30 wt% of Fe were purified by the 2-step process of air oxidation and successive washing with hydrochloric acid. The surface chemistry and pore structures of HCNT aggregates before and after purification were examined by X-ray photoelectron spectroscopy (XPS) and N-2 adsorption at 77 K. XPS results show that the purification treatment introduces carbon-based oxides groups on the surface of HCNT and removes the Fe from the HCNT aggregates. The N-2 adsorption isotherm on HCNT is of Type II and it changes to Type IV as a result of purification. Purification decreases the average pore width from 3.5 to 1.0 nm and develops the micropore structure. (C) 2002 Elsevier Science B.V. All rights reserved.