Adsorption isotherms for hydrogen on single walled nanotubes (SWNTs) subjected to various types of pretreatment have been measured by a tapered element oscillating mass analyzer. Isotherms at room temperature over a range of pressures up to 48 bar have been measured.

We demonstrate that activation of the SWNT samples by mild oxidation in CO2, followed by heat treatment in an inert atmosphere, increases the hydrogen adsorption capacity of the SWNT samples by about a factor of three at 48 bar.