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

Abstract

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.