A high-capacity hydrogen storage medium—Al-adsorbed graphene—is proposed based on density-functional theory calculations. We find that a graphene layer with Al adsorbed on both sides can store hydrogen up to $13.79\text{wt}\mathrm{\%}$ with average adsorption energy $-0.193\text{eV}/{\text{H}}_2$. Its hydrogen storage capacity is in excess of $6\text{wt}\mathrm{\%}$, surpassing U. S. Department of Energy (DOE’s) target. Based on the binding-energy criterion and molecular-dynamics calculations, we find that hydrogen storage can be recycled at near ambient conditions. This high-capacity hydrogen storage is due to the adsorbed Al atoms that act as bridges to link the electron clouds of the ${\text{H}}_2$ molecules and the graphene layer. As a consequence, a two-layer arrangement of ${\text{H}}_2$ molecules is formed on each side of the Al-adsorbed graphene layer. The ${\text{H}}_2$ concentration in the hydrogen storage medium can be measured by the change in the conductivity of the graphene layer.

• Received 22 October 2009

DOI:https://doi.org/10.1103/PhysRevB.81.205406