Diffusion, adsorption, and desorption of molecular hydrogen on graphene and in graphite

J Petucci and C LeBlond and M Karimi and G Vidali, JOURNAL OF CHEMICAL PHYSICS, 139, 044706 (2013).

DOI: 10.1063/1.4813919

The diffusion of molecular hydrogen (H-2) on a layer of graphene and in the interlayer space between the layers of graphite is studied using molecular dynamics computer simulations. The interatomic interactions were modeled by an Adaptive Intermolecular Reactive Empirical Bond Order (AIREBO) potential. Molecular statics calculations of H-2 on graphene indicate binding energies ranging from 41 meV to 54 meV and migration barriers ranging from 3 meV to 12 meV. The potential energy surface of an H-2 molecule on graphene, with the full relaxations of molecular hydrogen and carbon atoms is calculated. Barriers for the formation of H-2 through the Langmuir-Hinshelwood mechanism are calculated. Molecular dynamics calculations of mean square displacements and average surface lifetimes of H-2 on graphene at various temperatures indicate a diffusion barrier of 9.8 meV and a desorption barrier of 28.7 meV. Similar calculations for the diffusion of H-2 in the interlayer space between the graphite sheets indicate high and low temperature regimes for the diffusion with barriers of 51.2 meV and 11.5 meV. Our results are compared with those of first principles. (C) 2013 AIP Publishing LLC.

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