Ar, CCl4 and C6H6 adsorption outside and inside of the bundles of multi-walled carbon nanotubes - Simulation study

This is the first paper reporting the results of systematic study of the adsorption of Ar, C6H6 and CCl4 on the bundles of closed and opened multi-walled carbon nanotubes. Using grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations, we also study the effect of the introducing defects in the external and internal walls of osculating and separated nanotubes on Ar diffusion and on adsorption of all three adsorbates. The Ar diffusion coefficients obtained are very sensitive to the presence of defects. Simulated isotherms are discussed to show the relation between the shapes of the high resolution s-plots and the mechanisms of adsorption. From obtained data, as well as from geometric considerations, from the VEGA ZZ package, and from simulations (ASA), the values of surface areas of all nanotubes are calculated and compared with those obtained using the most popular adsorption methods (BET, s and the A,B,C-points). We show that the adsorption value for the C-point of the isotherm should be taken for the calculation of the specific surface area of carbon nanotubes to obtain a value which approaches the absolute geometric surface area. A fully packed monolayer is not created at the A-, B- or C-points of the isotherm; however, the number of molecules adsorbed at the latter point is closest to the number of molecules in the monolayer as calculated via the ASA method, the VEGA ZZ package or from geometric considerations