Density-functional calculations were employed to study the molecular dissociation of hydrogen on graphene, the diffusion of chemisorbed atomic species, and the electronic properties of the resulting hydrogen on graphene system. The results showed that applying stress to the graphene substrate could lower the barrier to dissociation of molecular hydrogen by a factor of 6 and change the process from endothermic to exothermic. These values for the barrier and the heat of reaction, unlike the zero stress values, were compatible with the time scales observed in experiments. Diffusion, on the other hand, was not greatly modified by stress. The electronic structure was analyzed for configurations relevant to molecular dissociation and adsorption of atomic hydrogen on a graphene single layer. An absolute band gap of 0.5eV was found for the equilibrium optimum configuration for a narrow range of coverages (≈0.25). This value was in good agreement with experiment.

Hydrogen on Graphene under Stress: Molecular Dissociation and Gap Opening. McKay, H., Wales, D.J., Jenkins, S.J., Verges, J.A., De Andres, P.L.: Physical Review B, 2010, 81[7], 075425