To explore hydrogen mobility on graphene, density functional calculations were used to determine the magnitude of binding energy versus the diffusion barrier for graphene, considering the effects of hole and electron doping, B and N substitutional dopants, and oxygen hetero-atoms. Although C-H binding energy and the barrier for chemical diffusion were not correlated, the binding energy of H in the lowest energy site on top of a C atom correlated with the binding energy of H over a "bridge" C-C bond, which was the transition state for chemical diffusion. Using this framework, it was demonstrated that both B substitutionally doped graphene and hydoxylated graphene have the potential to simultaneously meet thermodynamic and kinetic constraints for reversible room-temperature hydrogenation. The constraints demonstrated that reversible room-temperature hydrogenation was possible only when H diffused in a chemically bound state.

Atomic Hydrogen Diffusion on Doped and Chemically Modified Graphene. Lueking, A.D., Psofogiannakis, G., Froudakis, G.E.: Journal of Physical Chemistry C, 2013, 117[12], 6312-9