Nuclear Quantum Effects in the Layering and Diffusion of Hydrogen Isotopes in Carbon Nanotubes

Although recent experimental studies have demonstrated that H2 and D2 molecules wet the inner surface of supergrowth carbon nanotubes at low temperatures, characterization of the structural and dynamical properties in this regime is challenging. This Letter presents a theoretical study of self-diffusion in pure and binary H2, D2, and T2 contact monolayer films formed on the inner surface of a carbon nanotube. Our results show that monolayer formation and self-diffusion both in pure hydrogen isotopes and in H2/T2 and H2/D2 isotope mixtures is impacted by nuclear quantum effects, suggesting potential applications of carbon nanotubes for the separation of hydrogen isotopes.