A surfactant-free water-processable all-carbon composite and its application to supercapacitor

An easy technique is proposed to prepare a new surfactant-free water-processable supercapacitive material composed of graphene oxide (GO) and pristine graphene (PG). GO and PG are prepared by a modified Hummer's method and direct liquid phase exfoliation of graphite in dimethyl sulfoxide (DMSO) respectively. Water-processable GO/PG composites can be conveniently fabricated by mixing colloidal GO/H2O and PG/DMSO dispersions. The GO/PG composites can be re-dispersed in water to form stable colloidal dispersions. Capacitive behaviors of GO, PG and GO/PG composites were tested by cyclic voltammetry, galvanostatic charge/discharge curves and electrochemical impedance spectroscopy in aqueous electrolyte solutions. GO/PG composites exhibited improved capacitive properties in terms of specific capacitance and cycling stability, compared to those of individual components. The enhanced performances of the GO/PG composites signify the importance of the surface chemical property and conductivity of carbon-based materials for supercapacitor applications.