Interaction of cesium adatoms with free-standing graphene and graphene-veiled SiO2 surfaces

Abstract

The interaction of Cs adatoms with mono- or bi-layered graphene (MLG and BLG), either free-standing or on a SiO₂ substrate, was investigated using density functional theory. The most stable adsorption sites for Cs are found to be hollow sites on both graphene sheets and graphene-veiled SiO₂(0001). Larger dipole moments are created when a MLG-veiled SiO₂(0001) substrate is used for adsorption of Cs atoms compared to the adsorption on free-standing MLG, due to charge transfer occurring between the MLG and the SiO₂ substrate. For the adsorption of Cs on BLG-veiled SiO₂(0001) substrate, these differences are smoothed out and the binding energies corresponding to different sites are nearly degenerate; smaller dipole moments created by the Cs adatoms on BLG compared to MLG are also predicted.