3D mesoporous hybrid NiCo2O4@graphene nanoarchitectures as electrode materials for supercapacitors with enhanced performances

3D mesoporous hybrid NiCo2O4@graphene nanoarchitectures were successfully synthesized by a combination of freeze drying and hydrothermal reaction. Field-emission scanning electron microscopy (FESEM) and TEM analyses revealed that the NiCo2O4@graphene nanostructures consist of a hierarchical mesoporous sheet-on-sheet nanoarchitecture with a high specific surface area of 194 m(2) g(-1). Ultrathin NiCo2O4 nanosheets, with a thickness of a few nanometers and mesopores ranging from 2 to 5 nm, were wrapped in graphene nanosheets and hybrid nanoarchitectures were formed. When applied as electrode materials in supercapacitors, the hybrid NiCo2O4@graphene nanosheets exhibited a high capacitance of 778 F g(-1) at a current density of 1 A g(-1), and an excellent cycling performance extending to 10 000 cycles at a high current density of 10 A g(-1).