First principles investigation on carbon nanostructures functionalized with borane: An analysis on their hydrogen storage capacity

From first principles calculation, we have shown that the large radius single walled carbon nanotube (SWCNT) functionalized with borane can have appreciable hydrogen storage capacity. In addition, the average binding energy (0.21 eV/H₂) lies within the range recommended for the reversible adsorption. The BH₃ molecules adsorbed on the SWCNT do not undergo clustering, which has been a major hindrance for the functionalized SWCNT to get qualified as a hydrogen storage medium. The borane molecules absorbed on the SWCNT and carbon atoms in the SWCNT form borane organic scaffolds that adsorb hydrogen molecules via charge induced dipole interaction apart from the van der Waals interaction. We have extended the study to other carbon nanostructures namely, graphene and C₆₀. We have analyzed whether these systems are capable of absorbing borane and then adsorb hydrogen molecules. In the case of graphene and C₆₀, we could achieve functionalization to some extent but not hydrogenation. These results highlight the curvature dependent interactions present in these graphitic materials.