The diffusion of hydrogen and deuterium monomers on hole-doped graphene (a planar graphitic lattice), the outside wall and the inside wall of hole-doped (6,0) single-walled carbon nanotubes (a curved graphitic lattice) was investigated using density functional theory and density functional perturbation theory. The jump frequencies for the over-barrier transition and phonon-assisted quantum tunnelling were calculated by transition state theory and small-polaron theory, respectively. The effects of the local curvature of the surface and the hole doping on the thermodynamic and kinetic properties of a hydrogen monomer on these graphitic lattices were discussed. The results demonstrated that it was sufficient to judge the diffusional mobility of a hydrogen monomer on graphitic lattices from just the over-barrier transition, no matter how much it was curved and hole doped, while the quantum tunnelling could be safely neglected because it was significantly suppressed by the covalent bonding of hydrogen with the graphitic lattice

The Diffusion of Hydrogen Monomers on Hole-Doped Graphitic Lattices: Over-Barrier Transition and Quantum Tunneling. Huang, L.F., Ni, M.Y., Zeng, Z.: Journal of Physics - Condensed Matter, 2011, 23[43], 435007