▎ 摘　　要

Manganese oxide (MnO2)/three-dimensional (3D) reduced graphene oxide (RGO) composites were prepared by a reverse microemulsion (water/oil) method. MnO2 nanoparticles (3-20 nm in diameter) with different morphologies were produced and dispersed homogeneously on the macropore surfaces of the 3D RGO. Scanning electron microscopy and transmission electron microscopy were applied to characterize the microstructure of the composites. The MnO2/3D RGO composites, which were annealed at 150 degrees C, displayed a significantly high specific capacitance of 709.8 F g(-1) at 0.2 A g(-1). After 1000 cycles, the capacitance retention was measured to be 97.6%, which indicates an excellent long-term stability of the MnO2/3D RGO composites. (C) 2015 Elsevier Ltd. All rights reserved.