Mechanical and electrical properties of carbon nanotubes and graphene layers functionalized with amines

In the present paper, we study the effects of functionalization of graphene monolayers (GL) and single carbon nanotubes (CNT) with two types of amines NH, and NH2, analyzing structural, elastic and electronic properties of the structures. We have performed DFT calculations for GL and CNT with various densities of the attached amine molecules. We have determined the changes in the geometry, adsorption and binding energies, the Young's modulus, and the band structure as a function of the density of the adsorbed molecules. We observe characteristic effects such as rehybridization of the bonds induced by fragments attached to graphene and nanotubes and deformation of systems that results further in decrease of the Young's modulus. We also show that the band gap in GLs increases with the density of adsorbed molecules, whereas it decreases in CNTs. Our calculations reveal that the amines exhibit the strong cohesion to GLs and CNTs. Further, we determine the critical density of the NH fragments that leads to the closing of the band gap in functionalized CNT. We also show how to engineer the magnitude of the band gap by functionalizing graphene with NH2 and NH groups of various concentrations.

► We calculate mechanical and electrical properties of graphene and carbon nanotubes functionalized with amine molecules. ► Amine molecules NH and NH2 build strong covalent bond to graphene and carbon nanotubes. ► Young's modulus of functionalized systems is smaller than of pure ones. ► Functionalization of graphene layer with NH and NH2 opens fundamental band gap.