NiCo2O4 nanosheet supported hierarchical core-shell arrays for high-performance supercapacitors

Two types of homogeneous NiCo2O4 nanosheet@ NiCo2O4 nanorod and heterogeneous NiCo2O4 nanosheet@ NiO nanoflake hierarchical core- shell arrays are synthesized via facile solution methods in combination with a simple thermal treatment. In both cases, the NiCo2O4 nanosheets serve as the core backbone for anchoring the shell materials. The two as- prepared hierarchical nanoarrays are evaluated as supercapacitor electrodes and demonstrate excellent electrochemical performance with high specific capacitance (1925 and 2210 F g(-1) for NiCo2O4@ NiCo2O4 and NiCo2O4@ NiO at 0.5 A g(-1), respectively), good rate capability, and superior cycling stability. The superior capacitive performance is mainly due to the unique hierarchical core- shell architecture with faster ion/electron transfer, improved reactivity, and enhanced structural stability. Our work can allow for the fabrication of various NiCo2O4 nanosheet supported hierarchical nanostructures for applications in energy storage, catalysis, and sensing.