Computational modelling of the adsorption and flow of various types of gas in nanotubes forms a very active area of research. The adsorption can take place inside SWCNTs and, in the case of a bundle of SWCNTs, it can also take place at three additional bundle sites. These sites are the interstitial channels between the SWCNTs, i.e. the interior space between the SWCNTs in the bundle, the outer surfaces of the nanotubes composing the rope, and the ridges (or groove) channels, i.e. the wedge-shaped spaces that run along the outer surface of the rope where two SWCNTs meet. Computational modelling studies that we will consider show that while H2, He and Ne particles can adsorb in the interstitial channels, other types of atom are too large to fit into such tiny spaces. As a result, the clarification of the adsorption sites, to determine where a given gas atom can be accommodated, is a focal point of research. The insight obtained from this research has important ramifications for the application of nanotechnology to gas-storage devices, molecular sieves and filtration membranes. We will first consider the all-important case of modelling hydrogen storage in nanotubes.

Atomic and molecular hydrogen in nanotubes

Modelling H2 storage in carbon nanotubes occupies a very prominent position in the ongoing research in this field, and several, rather detailed, numerical simulations have been devoted to the study of various aspects of this problem.