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.

Graphical abstractWe have investigated the hydrogen storage capability of large diameter single walled carbon nanotubes (SWCNTs) and other two different nanostructures namely graphene and C60, functionalized with borane. The SWCNT (10, 10) functionalized with borane is able to adsorb 6.12 wt% of hydrogen with the average binding energy (0.21 eV/H2), which lies within the range recommended for the reversible adsorption. In the case of graphene and C60, we could achieve functionalization to some extent but not hydrogenation.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Large radius SWCNTs functionalized with BH3 have appreciable hydrogen storage capacity. ► No clustering of BH3 molecules, hence SWCNT-BH3 qualifies as a good hydrogen storage medium (HSM). ► Storage capabilities of other carbon nanostructures, graphene and C60 (host) are investigated. ► Interaction between BH3 and carbon nanostructure strongly depends on the curvature of the host. ► Suitable host material with active interacting surface states is necessary for a good HSM.