Mechanisms of Hydrogen Transport in Flexible-Wall Narrow Carbon Nanotubes

Figure 2

(a)–(d): mean square displacement curves, that is, mean square displacement curves of hydrogen molecules along the pore axis (~Ų) as function of time for simulation temperatures of = 100 K, 300 K, 500 K, and 800 K, respectively. Note that the green, turquoise, blue, red, and violet lines correspond to particle loadings of 10, 30, 50, 70, and 90 adsorbed hydrogen molecules, respectively. In addition, the three black lines represent the scaling behavior expected for the ballistic diffusion mechanism (dashed), the Fickian mechanism (solid), and the single-file diffusion mechanism (dashed-dotted), respectively.

(a) 100 K

(b) 300 K

(c) 500 K

(d) 800 K