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

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. ‫٭‬ Corresponding author. Fax: +32 3 2653204. E-mail: Abdiravuf.Dzhurakhalov@ua.ac.be a http://webbook.nist.gov/chemistry/ b http://srdata.nist.gov/cccbdb/

Ab initio studies of isolated hydrogen vacancies in graphane

“…In the case of hydrogen di-vacancy, the ortho configuration c 2 (1.16 eV) is more energetically favourable than the meta c 3 (4.32 eV) and the para c 4 (4.46 eV). Dzhurakhalov et al [47] studied the chemisorption of the ortho, meta and para configurations of hydrogen isomers on graphene monolayer and reported the same stability trend. Our obtained formation energy value for c 3 agrees very well with that reported by Wu et al [39].…”

Morphing Graphene-Based Systems for Applications: Perspectives from Simulations

“…In contrast to physisorption, chemisorption on graphene is a barrier-driven process, requiring a change in hybridization from sp 2 to sp 3 [64,65]. The barrier for atomic H is estimated around 0.3 eV, but the barrier for H 2 , involving dissociative chemisorption, is ∼1.5 eV per atom.…”

On Thermodynamic Stability of Hydrogenated Graphene Layers, Relevance to the Hydrogen on-board Storage

“…(5) the known experimental values of ∆H 4 = -2.26 eV/atom and ∆H 3  -0.05 eV/atom [25,45], and also the theoretical value [3] of ∆H 1 = -0.15 эВ/atom, one can obtain a desired value of ∆H 2 = -2.5 ± 0.1 eV/atom. The quantity of -∆H 2 characterizes the break-down energy of C-H sp 3 bond in graphane ( Fig.…”

“…In a number of works, it shows that hydrogen chemisorption corrugates the graphene sheet in fullerene, carbon nanotubes, graphite and graphene, and transforms it from a semimetal into a semiconductor [3,5,[25][26][27][28]. This can even induce magnetic moments [29][30][31].…”

“…Single-side hydrogenated graphene (SSHG) of CH composition [7,25] is an alternative to graphane, in which hydrogen atoms are adsorbed only one side. In contrast to graphone, they are adsorbed on all carbon atoms rather than on every second carbon atom.…”