Ab initio studies on the hydrogenation at the edges and bulk of graphene

Abstract

The opening of a band gap in graphene through chemical functionalization and realization of nanostructures, is an important issue for technological applications. Using first principles density functional theory, we show that how one can modify the electronic structure of bulk and nanoribbons of graphene by hydrogenation. It is shown that the hydrogenation of bulk graphene occurs through the formation of compact hydrogenated C islands. This also paves a unique way to realize zigzag and armchair nanoribbons at the interfaces between hydrogenated and bare C atoms and opens up the possibility to tune the band gap by controlling the width of the graphene-graphane interface. Moreover, we have studied the stability of hydrogenated edges of nanoribbons at finite temperature and pressure of hydrogen gas. It is shown that a dihydrogenated edge, which opens up a gap, can be stabilized under certain thermodynamic conditions.