Theoretical study of fast diffusion in carbon nanontubes

Abstract

Using a recently reported method for the statistical representation of gaseous diffusion within a cylindrical pore, we report here on an analysis of situations that describe fast diffusion within carbon nanotubes. It is proposed that if gaseous flow properties of the tube, in the highly rarefied situation, are due to there being only specular particle–wall reflections, then these particles can transit the tube via self-diffusion. On comparing this self-diffusive flux with Knudsen transport diffusion, our model predicts that enhanced diffusion is indeed possible in the carbon nanotube. Depending upon the statistical nature of the particle–wall scattering phenomenon, the enhancements are predicted be three to four times that of classical transport diffusion and, for certain conditions, the enhancement factor can be greater than 4.

Gaseous density layering within carbon nanotubes: An analytic model

“…The nature of gaseous flow within these tubes has been vigorously investigated. Also of significant interest is the peculiar fast diffusion phenomenon that has been identified experimentally and confirmed theoretically for such nanopores [5,6,7]. Though analytic methods have been developed in a effort to help describe gaseous flow within such tubes [8,9], computer simulations, employing molecular dynamics (MD) and Monte Carlo methods, are often the preferred method of investigation [10,11,12].…”