High-capacity hydrogen storage by metallized graphene

Recently, much effort has been devoted to engineer carbon based nanostructures, which can absorb H2 molecules with high storage capacity, but can release them easily in the course of consumption in fuel cells. Insufficient storage capacity, slow kinetics, poor reversibility, and high dehydrogenation temperatures have been the main difficulties toward acceptable media for hydrogen storage.

Recently, graphene, a single atomic plane of graphite, has been produced showing unusual electronic and magnetic properties. Our study based on first-principles plane wave calculations predicts that Li can be adsorbed on graphene forming a uniform and stable coverage on both sides. A significant part of the electronic charge of the Li 2s orbital is donated to graphene and causes excess charges on graphene. As a result, semimetallic graphene and semiconducting graphene ribbons change into good metals. It is even more remarkable that Li covered graphene can serve as a high-capacity hydrogen storage medium with each adsorbed Li absorbing up to four H2 molecules amounting to a gravimetric density of 12.8 wt %.

C. Ataca, E. Aktürk, S. Ciraci, H. Ustunel
Published in Appl. Phys. Lett. 93, 043123 (2008)