Graphene nanoplatelets supported MnO2 nanoparticles for electrochemical supercapacitor

► MnO2 nanoparticles coated onto recently discovered 2-D graphene nanoplatelets were fabricated. ► High-performance electrodes for supercapacitors were produced by using the new hybrid material. ► The maximum capacitance and energy density obtained for this nanocomposite were 542 F/g and 75.3 Wh/kg at a scan rate of 0.01 V/s in 2 M KCl. ► A synergistic effect between GNPs and MnO2 combine the remarkable electrical conductivity of GNPs with the high pseudocapacitance of the MnO2 nanoparticles.