Energetics and Electronic Structures of Alkanes and Polyethylene Adsorbed on Graphene

We report on total-energy electronic-structure calculations performed for linear alkanes [CnH2n+2 with n = 1 to 8] and polyethylene of infinite length, both of which are adsorbed on graphene, on the basis of the density functional theory. We find that graphene has a specific adsorption site for the alkane molecules, where multiple CH/pi interactions between the alkane molecule and graphene take place. The binding energy is calculated to be about 67 meV per CH2 unit, being close to the typical value of CH/pi interaction. The electronic structure of the alkane-adsorbed graphene originates primarily from that of graphene near the Fermi level. However, when a large amount of alkane molecules is adsorbed on graphene, the interactions between alkanes and graphene affect the electronic structures of graphene, leading to the opening of the energy gap by about 6 meV. (c) 2013 The Japan Society of Applied Physics