Green synthesis of holey graphene sheets and their assembly into aerogel with improved ion transport property

A green yet effective solution-based route for scalable preparation of holey graphene was developed by solvothermal reaction of graphene oxides (GO) in water-ethylene glycol system (H2O-EG). The O-2 molecules dissolved in H2O-EG system was found to serve as a moderate oxidant which can oxidize partial carbon atoms on GO sheets, leaving behind nanopores on graphene sheets. Importantly, by increasing the GO concentration to 2.0 mg mL(1), these holey graphene sheets can assemble into macroscopic aerogel (HGA). Benefiting from the in-plane nanopores, HGA showed much improved surface area as compared with the graphene aerogel built with non-holey graphene sheets (GA). The electrochemical characterization results showed that holey graphene sheets in HGA contributed to a higher specific capacitance, an improved rate capability and faster ion kinetic when serving as binder-free supercapacitor electrode. (C) 2016 Elsevier Ltd. All rights reserved.