The self-assembly of shape controlled functionalized graphene-MnO ₂ composites for application as supercapacitors

Graphene-MnO₂ nanocomposites with different morphologies were obtained by a facile self-assembly method. The formation mechanism of graphene-MnO₂ composites with different shapes of MnO₂ is discussed in detail. Nanostructured MnO₂ with different morphologies was distributed on the surface of graphene uniformly. The prepared graphene-MnO₂ composites could be used as electrode materials for supercapacitors. The graphene-MnO₂ (flowerlike nanospheres) composite (405 F g^-1) exhibited better capacitive performance than that of the graphene-MnO₂ (nanowires) composite (318 F g^-1) at a current density of 1.0 A g^-1. The synergistic effect of graphene and MnO₂ endowed the composite with high electrochemical capacitance. Moreover, the graphene-MnO₂ (flowerlike nanospheres) composite showed a fast charge-discharge process and high cyclic stability.