A novel solvothermal synthesis of Mn3O4/graphene composites for supercapacitors

Mn3O4/graphene (GM) composites were prepared via a simple solvothermal process by mixing Mn(AC)2·4H2O and graphite oxide (GO) suspension in mixed ethanol/H2O. As characterized by scanning electron microscopy and transmission electron microscopy, Mn3O4 nanoparticles with size of 37–50 nm are effectively anchored in graphene sheets. Cyclic voltammetry and galvanostatic charge–discharge measurements were adopted to investigate the electrochemical properties of GM composites in 1.0 M Na2SO4 solution. In a potential window of −0.2 to 0.8 V vs. SCE, the composites deliver an initial specific capacitance of 161.0 F g−1 at 1 A g−1 and increase to 230 F g−1 after 1000 cycles, while significant capacitance fading for pure Mn3O4. At a high current density of 5 A g−1, the specific capacitances of 116 F g−1, 22.5 F g−1 are exhibited for the Mn3O4/graphene composites and pure Mn3O4, respectively, indicating that graphene greatly enhances the electrochemical performance of Mn3O4.

► A simple route to synthesize nanocrystalline Mn3O4/graphene (GM) composites that Mn3O4 nanoparticles are homogeneously embedded in highly reduced graphene oxide nanosheets.
► The GM composites provides higher surface area interface between Mn3O4 nanopaticles and the electrolyte which promote fast Faradic charge and discharge of the Mn3O4 nanoparticles.
► The GM composites electrode exhibits better specific capacitance and good cycling life at high current density.