Ionic Liquid-Graphene Interface: Effect of Anions on the Fermi Level

Since energy conversion and storage processes take placeat theelectrolyte-electrode interface, it is important to developexperimental and theoretical procedures to understand the interfacialnanostructure in graphene-based electrochemical storage devices whereionic liquids (ILs) are used as electrolytes. In this contribution,the impact of the anions of imidazolium-based ILs on the IL-grapheneinterface as well as on the electronic structure of graphene is investigated.Raman spectroscopy unveils that 1-butyl-3-methylimidazolium ILs havingsmaller anions induce n-type doping, while ILs with larger anionshave a negligible effect on the doping. Molecular modeling simulationsreveal that changes in the electrostatic potential at the IL-grapheneinterface are responsible for the n-type doping.