[en] Although hydrogen is one of the most efficient fuel per unit of mass, its low density per unit volume requires high pressure gaseous storage or cyrogenic storage in liquid form for practical applications. A promising technique to reduce the pressure requirements for gaseous storage is to use the adsorption properties of carbon materials. However, physisorption of hydrogen on activated carbon requires operating temperatures of the order of 77K and a proper densification of the carbon to exhibit appreciable gains over compression. Large absorbed densities of hydrogen have been reported on carbon nanostructures such as nanotubes and nanofibers, at or near room temperature. Adsorption storage of hydrogen using such carbon materials may therefore be possible at much higher temperatures than activated carbon. The precise mechanisms that could explain the large adsorbed densities is still not understood. Although physiosorption does not appear to be sufficient to explain by itself the large reported values of the adsorption density of nanotubes and nanofibers, it is interesting to study its contribution to the absorbed density and to compare it to other carbon structures such as activated carbon, particularly in view of the controversy surrounding the actual values of the absorbed density in carbon nanostructures. In this work, we will study the adsorption isotherms of hydrogen on caped and uncaped carbon nanotubes and nanotube ropes in the limit of Henry's Law by calculating the second virial coefficient for gas solid interaction and compare them to layered carbon structures
Source
Bose, T.K.; Benard, P. (eds.); 832 p; ISBN 0-9696869-5-1; 
; May 2000; p. 741-744; 10. Canadian Hydrogen Conference; Quebec, Quebec (Canada); 28-31 May 2000; Available from Institut de recherche sur l'hydrogene, Universite du Quebec a Trois-Rivieres, P.O. Box 500, Trois-Rivieres, Quebec, G9A 5H7; 6 figs.
; May 2000; p. 741-744; 10. Canadian Hydrogen Conference; Quebec, Quebec (Canada); 28-31 May 2000; Available from Institut de recherche sur l'hydrogene, Universite du Quebec a Trois-Rivieres, P.O. Box 500, Trois-Rivieres, Quebec, G9A 5H7; 6 figs.