Additive-Free Edge-Functionalized Graphene Dough

Abstract

The exploitation of graphene's extraordinary properties depends on finding new ways to synthesize and process it without disrupting its fundamental structure. Here, we demonstrate the synthesis of highly processable and dispersible edge-functionalized graphene (EFG) directly from graphite by a combination of selective oxidation and physical exfoliation. Microscopy and spectral characterization reveals few-layer graphene nanoplatelets with defect-free basal planes and carboxylate and phenolic edge-functionalization. Its defect-free nature is reflected in its high conductivity (900 S cm−1). The EFG has excellent dispersibility (100 mg mL−1) in aqueous and organic solvents and forms a soft graphene dough that can be molded to any geometric shape. The dried dough can readily reabsorb a wide variety of solvents indicative of a highly porous and amphiphilic material. The unique properties of the graphene dough are demonstrated with the formation of a 3D-printed conductive scaffold, a printed circuit on paper, and the fabrication of a paramagnetic graphene dough. Significantly, free-standing and 3D-printed supercapacitors can be fabricated from ionic liquid-impregnated dough that gives an excellent gravimetric capacitance of 210 F g−1 and a high energy density of 262.5 Wh Kg−1. This high capacitance is synonymous with efficient pore utilisation during charge storage and supports the unique amphiphilic, nanoporous EFG structure.