Prediction of energetically optimal single-walled carbon nanotubes for hydrogen physisorption

Abstract

Hydrogen storage by carbon nanotubes (CNTs) is a challenging issue still in debate. Using an approximate density functional method augmented with a van der Waals dispersion term, we have shown that there are binding maxima for H2/single-walled carbon nanotube (SWCNT) complexes at (5, 5) and (8, 0) tubes for armchair and zigzag CNTs, respectively, with binding energies around three times as large as that of H2 on graphene surface. We predict that SWCNTs with diameters of 6–7 Å are energetically optimal candidates for physisorption of molecular hydrogen.