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arXiv · 0808.1312

Understanding adsorption of hydrogen atoms on graphene

Simone Casolo·Ole Martin Lovvik·Rocco Martinazzo·Gian Franco Tantardini
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Abstract

Adsorption of hydrogen atoms on a single graphite sheet (graphene) has been investigated by first-principles electronic structure means, employing plane-wave based, periodic density functional theory. A reasonably large 5x5 surface unit cell has been employed to study single and multiple adsorption of H atoms. Binding and barrier energies for sequential sticking have been computed for a number of configurations involving adsorption on top of carbon atoms. We find that binding energies per atom range from ~0.8 eV to ~1.9 eV, with barriers to sticking in the range 0.0-0.2 eV. In addition, depending on the number and location of adsorbed hydrogen atoms, we find that magnetic structures may form in which spin density localizes on a $\sqrt{3}{x}\sqrt{3}{R}30^{\circ}$ sublattice, and that binding (barrier) energies for sequential adsorption increase (decrease) linearly with the site-integrated magnetization. These results can be rationalized with the help of the valence-bond resonance theory of planar $π$ conjugated systems, and suggest that preferential sticking due to barrierless adsorption is limited to formation of hydrogen pairs.

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Simone Casolo, Ole Martin Lovvik, Rocco Martinazzo, Gian Franco Tantardini. 2008-08-08. Understanding adsorption of hydrogen atoms on graphene. https://doi.org/10.1063/1.3072333

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