Interaction of hydrogen isotopes with carbon nanostructures

The atomic nature of hydrogen storage in single wall carbon nanotubes (SWNTs) has been investigated by thermal desorption spectroscopy utilizing mass spectrometry. The partial pressures of desorbed H-2, D-2, and HD have been simultaneously recorded after sample loading with a 1:1 mixture of H-2 and D-2 gases. The amount of desorbed HD molecules approaches the ratio 2:1:1 for HD:H-2:D-2 in the case of atomic storage, i.e. chemisorption. In the case of storage as molecules, i.e. physisorption, the concentration of HD approaches the background level. Hydrogen isotopes are absorbed as atoms in SWNT samples containing transition metals from either sample production (Ni, Fe,...) and/or activation (opening) process (Ni, Fe, Ti,...). Purified SWNTs adsorb hydrogen molecules at low temperatures. (C) 2003 Elsevier B.V. All rights reserved.