Effect of purification on pore structure of HiPco single-walled carbon nanotube aggregates

HiPco single-walled carbon nanotube (HPNT) containing Fe was purified by one-step purification with HCI-washing (D-method) and two-step purification with HCI-washing after air oxidation (GD-method). The N-2 adsorption isotherm of HPNT at 77 K is of type If and it changes to type IV after purification. Purification by the 0 and GD methods increases the total surface area and micropore volume, and it decreases the average pore width from 3.5 nm to 1.7 and 1.0 nm, respectively.