Thin Co3O4 nanosheet array on 3D porous graphene/nickel foam as a binder-free electrode for high-performance supercapacitors

Transition metal oxide nanostructures are one of current investigation focuses for supercapacitors. We herein report a novel and facile approach to fabricate Co3O4 nanosheet arrays on 3D porous graphene/nickel foam. A graphene layer with the sharp edges and wrinkles is obtained on nickel foam by an electrophoretic deposition (EPD). The 2D thin Co3O4 nanosheets are further grown on the 3D porous graphene/nickel foam substrate through a hydrothermal synthesis, forming a 3D hierarchically porous architecture. The as-fabricated thin Co3O4 nanosheet array on graphene/nickel foam delivers a high specific capacitance of 3533 F g(-1) at a current of 1 A g(-1). The array electrode still shows a specific capacitance of 2222 F g(-1) even at a high rate (20 A g(-1)), demonstrating its prominent rate capability. Furthermore, the array electrode also exhibits the excellent electrochemical cycling stability with a specific capacitance of 2459 Fri after 2000 cycles at a current of 8 A g(-1). The superior pseudocapacitive performance of the array electrode can be attributed to its unique structure characteristics. The thin Co3O4 nanosheet array electrode with superior pseudocapacitive performance reveals the promising potential as a high-performance electrode for supercapacitors. (C) 2015 Elsevier Ltd. All rights reserved.