Density functional theory was used to investigate the chemisorption and diffusion of H atoms on the surface of single-walled carbon nanotubes. The results showed that the binding energy of a single hydrogen atom on the nanotube surface decreased as the diameter of the tube increased and was little affected by the chirality of the tube. Two hydrogen atoms favored binding at adjacent and opposite positions rather than at alternate carbon sites. With regard to the diffusion of H atoms on the tube, it was found that an isolated H atom could diffuse rather than desorb on small nanotubes upon heating. As the tube diameter increased, the diffusion barrier for H atoms on the surface decreased. When the H atom diffused around another H atom, the diffusion barriers varied with the relative sites of the two H atoms.

Chemisorption and Diffusion of Hydrogen Atoms on Single-Walled Carbon Nanotubes. M.Ni, Z.Zeng: Journal of Nanoscience and Nanotechnology, 2010, 10[8], 5408-12