First-principles study of adsorption of alkali metals (Li, na, k) on graphene

Abstract

We have performed the first-principles study of adsorption of alkali metals like lithium, sodium and potassium on graphene. As first-principles methods we have chosen Hartree–Fock method and density functional theory (DFT) method. We have studied the variation of energy of grapheme clusters on sizes of the graphene clusters. Our findings show that the energy of graphene clusters increases with the size of the clusters and for the cluster size more than 30 carbon atoms the energy per carbon atom remains almost constant. This shows that the graphene clusters are stable with respect to energy for the larger size of clusters. The adsorption of alkali metals on the H-grpahene clusters have been studied. The adsorption energy of alkali metal atoms (Li, Na and K) on H-graphene increases on increasing the size of H-graphene cluster. The dependence of the computed adsorption energies of Li, Na and K atoms on the size of H-graphene clusters and the presence of large dipole moments in the adatoms-H-graphene system exhibit the ionic character of the alkali metal adatom-H-graphene interaction. Our findings on the adsorption energy of the alkali metals on H-graphene clusters agree with the previously reported data.