Physisorption of molecular hydrogen in curved carbon nanomaterials: a computational study

Abstract

Hydrogen physisorption on carbon nanomaterials is a promising method of hydrogen storage because carbon materials are cheap, abundant and light weight. However, storage is difficult because dispersion forces between C and H are weak. Curved carbon substrates are more promising than planar systems because the increased level of sp 3 -hybridization enhances H2 physisorption. The present study uses density functional theory to model large fullerenes, single-walled carbon nanotubes and graphene to investigate the interaction with H2; decorating platinum is also considered. We conclude that H2 can be stored in fullerenes without an energy input if the H2 molecules are more than 3 A from the carbon surface and more than 2 A from each other. In addition, confinement effects are observed when hydrogen is stored in fullerenes rather than nanotubes – storage in nanotubes is more favourable for systems with small diameters.