Electrochemical assembly of reduced graphene oxide/manganese dioxide nanocomposites into hierarchical sea urchin-like structures for supercapacitive electrodes

The hierarchically sea urchin-like structured reduced graphene oxide (RGO)-manganese dioxide (MnO₂) nanocomposites have been assembled through an electrochemical deposition. MnO₂ particles are uniformly grown and directly deposited onto the surface of three dimensional (3D) RGO. The crystalline phase, size and composition of MnO₂ nanoparticles are γ phase, about 6 nm and 60 wt%, respectively. The specific capacitance of 125.93 F g⁻¹ of 3D RGO-MnO₂ composite is higher than 38.45 F g⁻¹ of MnO₂. The composite reveals the good rate capability of 70.29% and cyclic stability of ∼80% after 5000 cycles.