First principles studies for the dissociative adsorption of H2 on graphene

We investigate and discuss the interaction of H-2 with graphene based on density functional (DFT) theory. We calculate the potential energy surfaces for the dissociative adsorption of H-2 on highly symmetric sites on graphene. Our calculation results show that reconstructions of the carbon atoms play an important role in the H-2 -graphene interactions. Activation barrier for H-2 dissociation on an unrelaxed graphene is considerably high, similar to4.3 eV for a T-H-T geometry and similar to4.7 eV for a T-B-T geometry. The T-H-T(T-B-T) geometry means that the center of mass position of H-2 is at the hollow(bridge) site, and the two H atoms are directed towards the top sites on the graphene. On the other hand, when the carbon atoms are allowed to relax, the activation barrier decreases, and becoming 3.3 eV for the T-H-T geometry and 3.9 eV for the T-B-T geometry. In this case, the two carbon atoms near the hydrogen atoms move 0.33 Angstrom towards the gas phase for the T-H-T geometry and 0.26 Angstrom for the T-B-T geometry. (C) 2003 American Institute of Physics.