Graphene-based three-dimensional hierarchical sandwich-type architecture for high performance supercapacitors

A facile two-step method is developed for large-scale preparation of graphene-based three-dimensional hierarchical sandwich-type architecture (graphene/carbon nanotubes (CNTs)/Mn2O3) for high performance supercapacitor. The synthesis involves a chemical vapor deposition (CVD) method to fabricate sponge-like three-dimensional (3D) graphene/CNTs and an electrodeposition process to deposit Mn2O3 nano-sheets on the surface of 3D graphene/CNTs. With the novel sandwich-type composite as an electrode, the measurements indicate the synergy effects of Mn2O3 and 3D carbonous materials make the electrode present a high specific capacitance. The composite electrode also presents a high reversible capacity, excellent cycle performance and rate capability. It could be concluded that the composite of Mn2O3 with 3D graphene/CNTs displays excellent synergy effects of transition-metal oxide and carbonous materials. This work also inspires in-depth research for the application of 3D graphene-based composites for high performance supercapacitors.