The Nature of Graphene Surfaces as Determined from the Wettability Studies of Basal and Edge Planes

Abstract

Effective exploitation of the electronic properties of graphene in aqueous medium has been limited due to lack of information about its wettability characteristics. In this paper, fundamental wettability studies of the face and edge planes of graphene were accomplished through contact angle measurements of the as-received and oxidized surfaces. Further, Raman spectroscopic studies were performed to analyze the effect of oxidation on the graphene surfaces based on the D and G bands. Atomic force microscopy (AFM) was used for surface force measurements to determine the iso-electric point (IEP) of the face and edge surface. The interaction of hydrophobic fullerene and hydrophilic fullerol nanoparticles on the graphene face and edge surfaces was studied through AFM imaging. The zeta potential measurements of the above mentioned carbon nanoparticles were also carried out to confirm that the interaction was due to hydrophobic or hydrophilic forces and not due to electrostatic interactions. In addition molecular dynamics and ab-initio simulations were also carried out to verify the interactions of the carbon nanoparticles with the graphite surfaces.