Metal-diboride nanotubes as high capacity hydrogen storage media

Abstract

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.