Hydrogen Adsorption and Penetration of Cx (x=58-62) Fullerenes with Defects

Density functional theory calculations were performed to investigate the endohedral and exohedral adsorption of a H2 molecule on the classical and nonclassical fullerenes Cx (x=58, 59, 60, 62) with seven-, eight-, and ninemembered rings. The amplitude of adsorption energies are within 0.03eV and the molecule-fullerene interaction belongs to van der Waals type. Penetration of a H2 molecule through different fullerene cages was discussed and the corresponding energy barriers were obtained. We find that the existence of large holes reduces the penetration barrier from 12.6 eV for six-membered ring on perfect C60 cage to about 8eV for seven-membered rings and to about 5eV for eight-membered rings.