Graphane

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Not to be confused with Grapheme, Graphene, or Graphyne.
Graphane
Identifiers
CAS number 1221743-01-6 N
Properties
Molecular formula (CH)n
Molar mass Variable
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Graphane is a two-dimensional polymer of carbon and hydrogen with the formula unit (CH)n where n is large. Graphane should not be confused with graphene, a two-dimensional form of carbon alone. Graphane is a form of hydrogenated graphene. Graphane's carbon bonds are in sp3 configuration, as opposed to graphene's sp2 bond configuration, thus graphane is a two-dimensional analog of cubic diamond.

The first theoretical description of graphane was reported in 2003[1] and its preparation was reported in 2009.

Full hydrogenation from both sides of a graphene sheet results in graphane,[2] but partial hydrogenation leads to hydrogenated graphene.[3] Now they usually imply that the term graphane is used for a case when all graphene's bonds are saturated with hydrogen atoms. All other configurations with partly covered surface of graphene usually named as "graphane-like" structures. Graphane and graphane-like structures can be formed by electrolytic hydrogenation of graphene or few-layer graphene or high-oriented pyrolytic graphite. In the last case mechanical exfoliation of hydrogenated top layers can be used.[4]

If graphene rests on a silica surface, hydrogenation on only one side of graphene preserves the hexagonal symmetry in graphane. One-sided hydrogenation of graphene becomes possible due to the existence of ripplings. Because the latter are distributed randomly, the obtained graphane is expected to be a disordered material in contrast to two-sided graphane.[3] Annealing allows the hydrogen to disperse, reverting to graphene,[5] the underlying kinetic mechanism of which has been revealed by theoretical simulations.[6]

p-doped graphane is postulated to be a high-temperature BCS theory superconductor with a Tc above 90 K.[7]

Any disorder in hydrogenation conformation tend to contract the lattice constant by about 2.0 percents, but hydrogenation will decrease the dependence of the lattice constant on temperature, which indicates the possible application of Graphane in precision instruments.[8]

Density functional theory calculations suggested that hydrogenated and fluorinated forms of other group IV (Si, Ge and Sn) nanosheets also present properties similar to graphane.[9]

References

  1. ↑ Sluiter, Marcel; Kawazoe, Yoshiyuki (2003). "Cluster expansion method for adsorption: Application to hydrogen chemisorption on graphene". Physical Review B 68 (8): 085410. Bibcode:2003PhRvB..68h5410S. doi:10.1103/PhysRevB.68.085410. 
  2. ↑ Sofo, Jorge O. et al. (2007). "Graphane: A two-dimensional hydrocarbon". Physical Review B 75 (15): 153401–4. arXiv:cond-mat/0606704. Bibcode:2007PhRvB..75o3401S. doi:10.1103/PhysRevB.75.153401. 
  3. ↑ 3.0 3.1 D. C. Elias et al. (2009). "Control of Graphene's Properties by Reversible Hydrogenation: Evidence for Graphane". Science 323 (5914): 610–3. arXiv:0810.4706. Bibcode:2009Sci...323..610E. doi:10.1126/science.1167130. PMID 19179524. 
  4. ↑ A. M. Ilyin et al. (2011). "Computer simulation and experimental study of graphane-like structures formed by electrolytic hydrogenation". Physica E 43 (6): 1262–65. Bibcode:2011PhyE...43.1262I. doi:10.1016/j.physe.2011.02.012. 
  5. ↑ Konstantin Novoselov. "Beyond the wonder material". Physics World August 2009, 27-30.
  6. ↑ L. F. Huang "et al." (2011). "Understanding the Band Gap, Magnetism, and Kinetics of Graphene Nanostripes in Graphane". J. Phys. Chem. C. 115: 21088. doi:10.1021/jp208067y. 
  7. ↑ G. Savini et al. (2010). "Doped graphane: a prototype high-Tc electron-phonon superconductor". Phys Rev Lett 105. arXiv:1002.0653v1. 
  8. ↑ L. F. Huang "et al." (2013). "Lattice dynamics and disorder-induced contraction in functionalized graphene". J. Appl. Phys. 113: 083524. Bibcode:2013JAP...113h3524F. doi:10.1063/1.4793790. 
  9. ↑ J. C. Garcia, D. B. de Lima, L. V. C. Assali, and J. F. Justo (2011). "Group IV Graphene- and Graphane-Like Nanosheets". J. Phys. Chem. C. 115: 13242. arXiv:1204.2875. doi:10.1021/jp203657w. 

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