Metal-diboride nanotubes as high capacity hydrogen storage media...

We investigate the potential for hydrogen storage of a new class of nanomaterials,
metal-diboride nanotubes. These materials have the merits of high density of binding
sites on the tubular surfaces without the adverse effects of metal clustering. Using the
TiB2 (8,0) and (5,5) nanotube as prototype examples, we show through first-principles
calculations that each Ti atom can host two intact H2 units, leading to a retrievable
hydrogen storage capacity of 5.5 wt%. Most strikingly, the binding energies fall in
the desirable range of 0.2-0.6 eV per H2 molecule, endowing these structures with the
potential for room temperature, near ambient pressure applications.