Graphene at interfaces

Abstract

Strong attractive interactions between extended π-systems of graphene in various graphites have been studied for several decades. However, to date, no effective scalable exfoliation mechanism has been reported to exclusively synthesize dispersible single layer graphene in liquid environments. The first feature of this thesis is to use the repulsive electrostatic effect to modify the geometry of [pi]-[pi] interaction of graphenes against attractive van der Waals interactions. We explored an electrochemical method, inducing the large offset from ideal tight stacked [pi]-[pi] geometry, to generate Hyperstage-1 graphite intercalation compounds. Subsequently, highly functionalized graphenes are spontaneously exfoliated from Hyperstage-1 graphite intercalation compounds by reaction with an aryl diazonium salt solution under electrochemical reducing conditions. The covalent functionalization of graphene successfully provided the appropriate chemical activity/reactivity for the desired applications. Through the reactivity of functional graphene, we developed the fluid-like graphene matrix to attain a superlubric state. In addition, Janus graphenes are simply synthesized by Meisenheimer complexes reactions of hydrocarbon, perfluorocarbon and water-soluble alkyl amines on the surface of graphene at room temperature. This approach opens the door to a rich variety of functional single layer graphenes for applications.