Abstract
A 3D graphene sheet-carbon nanotube (GS-CNT) structure with a good wetting property, high porosity, and large surface area is homogeneously deposited with active amorphous manganese oxide (a-MnO x ) by potentiodynamic deposition. The flowery a-MnO x nanostructure with ultra-slender petals (ca. 5-8 nm) on the framework of hierarchically porous GS-CNT matrix not only enables nearly full utilization of a-MnO x but also retains sufficient conductivity and porosity for the high-rate charge-discharge application. The use of a-MnO x on the 3D GS-CNT material produces a specific capacitance of MnO x of 1200 F g -1 which is much-higher than that of a pure a-MnO x electrode (C S,Mn = 233 F g -1 ). The specific energy and specific power of a-MnO x /GS-CNT are respectively as high as 46.2 Wh kg -1 and 33.2 kW kg -1 , revealing that our work conceptually provides a way to produce porous structures composed of graphene, carbon nanotubes, and various electroactive materials for high-performance energy storage devices. © 2012 Elsevier B.V. All rights reserved.