MnO₂ grown in situ on graphene@CNTs as electrode materials for supercapacitors

Three-dimensional (3D) graphene@CNTs@MnO₂ (GCM) nanocomposites materials have been fabricated by a facile two-step method. The structure, morphology and electrochemical properties of the 3D nanocomposites were investigated by XRD, TG, Raman, SEM, TEM and electrochemical measurements. The 3D forest-like rGO@CNTs (GC) serves as both the backbone and ideal electron pathway for MnO₂. With this sophisticated configuration, the 3D GCM nanocomposites exhibit a specific capacitance of 245 F g^-1 at 0.5 A g^-1, excellent cycling stability (91.4% retention after 2000 cycles at 1 A g^-1) and high rate capability. These excellent capacitive performances may make the as-prepared nanocomposites as promising electrode materials for supercapacitors.