The adsorption and fast transport of Xe in single walled carbon nanotubes

Abstract

Combined GCMC and MD simulations have been used to investigate the adsorption and diffusion of Xe gases in carbon nanotubes (CNTs) at different conditions. The influences of several factors, such as temperature, pressure and diameter of the CNTs, on the adsorption structure and diffusion rate of Xe atoms have been comprehensively studied. The Xe atoms form an ordered helix structure in the cylindrical radial direction of the CNT, and move in a spiral way. The mean square displacement (MSD) increases with increasing the temperature, while it increases first and then decreases with increasing the pressure. The pore size has a considerable impact on both the structure and number of adsorbed molecules in the CNT, where a smaller pore size accounts for faster diffusion. The Xe atoms diffuse much faster in CNT than zeolite. In contrast to a Fickian motion in zeolite, a ballistic diffusion mechanism is followed in CNTs.