Density functional theory study of the vibrational properties of hydrogenated graphene

Abstract: Graphene is a basic building block for carbon materials of all dimensionalities and exhibits many unique electronic properties. But, for future applications of graphene, further tuning its electronic band structure is necessary. Recently, it has been demonstrated that graphene can react with atomic hydrogen, which transforms this zero-band-gap semimetal into an insulator [[17] Elias et al., Science 323 (2009) 610]. Here we investigate the electronic and vibrational properties of graphene sheets with H in various configurations by means of first-principles calculations based on density-function theory. It is found that the hydrogenation not only effectively modulates the band gap of graphene but also leads to the band gap transition from direct to indirect. Meanwhile, the emerging of the sp3 type bonds induced by the hydrogenation may introduce some new vibrational modes in graphene, which play a key role in determining the spectra signatures of the resulting graphene derivatives. Our results provide a satisfactory explanation for the experimentally observed changes of the Raman spectra in graphene during the hydrogenation. [Copyright &y& Elsevier]