Structure and energetics of hydrogen chemisorbed on a single graphene layer to produce graphane

TL;DR

This study uses atomistic simulations to analyze hydrogen chemisorption on graphene, identifying stable configurations and structural changes, with implications for nanoengineering and hydrogen storage.

Contribution

It provides detailed insights into the energetics and configurations of hydrogen chemisorption on graphene using reactive empirical potentials.

Findings

Ortho hydrogen pairs are the most stable chemisorption configuration.

Full coverage of hydrogen results in the highest binding energy.

Chemisorption causes specific structural changes in graphene.

Abstract

Chemisorption of hydrogen on graphene is studied using atomistic simulations with the second generation of reactive empirical bond order Brenner inter-atomic potential. The lowest energy adsorption sites and the most important metastable sites are determined. The H concentration is varied from a single H atom, to clusters of H atoms up to full coverage. We found that when two or more H atoms are present, the most stable configurations of H chemisorption on a single graphene layer are ortho hydrogen pairs adsorbed on one side or on both sides of the graphene sheet. The latter has the highest hydrogen binding energy. The next stable configuration is the ortho-para pair combination, and then para hydrogen pairs. The structural changes of graphene caused by chemisorbed hydrogen are discussed and are compared with existing experimental data and other theoretical calculations. The obtained results will be useful for nanoengineering of graphene by hydrogenation and for hydrogen storage.