Self-assembly synthesis of graphene oxide double-shell hollow-spheres decorated with Mn3O4 for electrochemical supercapacitors

Novel graphene oxide double-shell hollow-spheres decorated with Mn3O4 nanocrystals were synthesized via a facile solvothermal self-assembly method. They had the uniform outer diameter in ca. 100 nm and the thickness of each shell in ca. 5 nm. The electrochemical supercapacitive properties of the prepared double-shell hollow-sphere composites showed the capacitance of 225 F g−1 at the scan rate of 5 mV s−1, high electrochemical stability that retained about 99.5% capacitance after cycling 6000 times, and the energy density as high as 34.1 Wh kg−1 at the power density of 251 W kg−1. These performances were superior to those of most reported planar graphene-Mn3O4 nanocomposites as well as pure Mn3O4 nanocrystals.