Structural and vibrational properties of amines adsorbed on graphene

Abstract

Graphene is a promising material whose properties can be tailored by adsorption of molecules on its surface. Amines, with the -NH2 group, act as an electron donating adsorbate. We have investigated via first principles (density functional theory) the adsorption of three different amines, namely aniline, benzylamine and phenethylamine, on graphene sheets and their subsequent effects on graphene’s structure, vibrational modes position and natural bonding orbitals (NBO) charge. All the amines physically adsorb on graphene, with aniline forming the strongest bond (Adsorption energy = 21.004 kJ mol −1), whereby the bending of the planar graphene sheet is observed due to aniline adsorption. However, after adsorption of benzylamine and phenethylamine, the graphene sheet’s structure does not change. The change in structure is reflected by the change in the position of the vibrational modes as well as on the NBO charge and the highest occupied molecular orbital-lowest unoccupied molecular orbital gap. Aniline’s experimental spectrum shows agreement with the results obtained from the simulation to within 3% error.