Some Unexpected Behavior of the Adsorption of Alkali Metal Ions onto the Graphene Surface under the Effect of External Electric Field

Abstract

Hungarian research Project [TAMOP-4.2.2.A-11/1/KONV-2012-0065]; Chinese-Hungarian Intergovernmental S&T Cooperation Programme [CH-5-21/2010, TET_10-1-2011-0126, TET_12_CN-1-2012-0040]In this work the interaction between alkali metal ions and a graphene surface with the absence and the presence of an external electric field applied perpendicular to the surface was investigated. M05-2X/6-31G(d) DFT calculations were performed to describe the adsorption properties. Results show that the electric field pushes the positively charged ion closer to the graphene, where the charge transfer between the alkali metal cations and the electron rich graphene surface increases. At a species-dependent certain strength of the electric field, the excess electrons cause negative charge on the alkali metal ion. This effect will promote the removal of the ion from the surface