Adsorption Patterns of Helium on Carbon and Cellulose Nanotubes: Molecular Dynamics Simulations

Molecular dynamics simulations were performed to study helium adsorption on carbon and cellulose nanotubes. Adsorption isotherms were analyzed at different temperatures and pressures. All adsorption isotherms for carbon and cellulose nanotubes were predicted to be of Langmuir shape type I. Helium adsorption was observed both inside and outside of open-ended tubes. Increasing temperatures caused lower helium adsorption on carbon and cellulose nanotubes. The calculated quantities confirmed that the adsorption capacity of the cellulose nanotube was greater than that of the carbon nanotube. The adsorption capacity, isosteric heat of adsorption and binding energy indicated that cellulose nanotubes as well as carbon nanotubes are proper materials for gas storage.

HELIUM ADSORPTION ON CARBON NANOCONES WITH DIFFERENT DISCLINATION ANGLE: MOLECULAR DYNAMICS SIMULATION

We have used molecular dynamics simulation to study the influence of disclination angle on helium adsorption capacity of carbon nanocones (CNCs). Adsorption capacities of 180°, 240° and 300° CNCs have been compared at various temperatures. The results indicate that helium atoms adsorb on internal and external surfaces of the CNCs. At saturation conditions, the endohedral adsorption coverage is decreased by increasing the disclination angle, while the exohedral adsorption coverage is independent of this angle. It is also found that temperature has a considerable effect on the adsorbed amount. Comparison of the adsorption on CNCs with carbon nanotubes indicates that the adsorption capacity of cones is greater than those of tubes. Our results confirm the fact that the CNCs are good candidate for gas storage.