An active line of contemporary research is dedicated to the adsorption and storage of hydrogen on metal-doped carbon materials. Using density functional theory and van der Waals corrections we have studied molecular and dissociative adsorption of H2 on neutral and cationic C60Con complexes with n = 1–8. The Co atoms form compact clusters on the surface of the fullerene. Dissociative chemisorption of one H2 molecule is more stable than molecular adsorption on neutral C60Con, with the only exception of C60Co. When C60Con is ionized, the electronic charge deficit remains localized in the cobalt cluster. The molecular and dissociative adsorption features on cationic C60Con+ and neutral C60Con complexes are in general similar, but some differences can be highlighted. Molecular and dissociative H2 adsorption on C60Co2+ are competitive; in fact, molecular adsorption is slightly more stable as a result of the localized electronic charge deficit on the Co dimer. Another difference is that the dissociative adsorption energies on some of the neutral C60Con complexes are substantially larger than the dissociative adsorption energies on the corresponding C60Con+ cationic complexes by amounts between 0.2 and 0.5 eV. Activation barriers for dissociation of the adsorbed H2 molecule strongly depend on the charge state and cluster size. These barriers help to interpret the adsorption state (molecular or dissociated) of experimentally produced hydrogenated C60Con+ complexes. Hydrogen saturation has been studied in two cases. C60Co adsorbs three H2 units in molecular form, and C60Con adsorbs up to thirteen H2 units, four dissociated and nine in molecular form.
