Nickel foam supported hierarchical NiCo2S4@NiFe LDH heterostructures as highly efficient electrode for long cycling stability supercapacitor

Layered double hydroxides (LDHs) based heterostructures provide an opportunity for the development of highperformance supercapacitors. Up till now, hierarchical NiCo2S4@NiFe LDH heterostructure is scarcely investigated for supercapacitor. In this work, the hierarchical NiCo2S4@NiFe LDH heterostructure nanosheet arrays on Ni-foam (NF) were synthesized by a facile hydrothermal method. As the supercapacitor electrode, it has been revealed that the incorporation of NiFe can significantly increase the capacitive performance of the heterostructure. At a current density of 1 Ag-1, a specific capacitance of NiCo2S4@NiFe LDH electrode was reached up to 827 Fg- 1, outperforming that of pristine NiCo2S4 and NiFe LDH. Moreover, the electrode keeps 90.2% of its preliminary capacitance after 12,000 cycles at 5 A g-1. In addition, NiCo2S4@NiFe LDH electrode offer high energy density of 38.1 W h kg-1 and power density of 1800 W kg-1. According to DFT calculations, NiFe-LDH adsorption on NiCo2S4 is strong and governed by large interfacial interactions with a charge transfer of 0.44 eV to NiCo2S4 surface thus demonstrating the significantly improved electrochemical performance. Hence, such an outstanding electrochemical finding suggest that NiCo2S4@NiFe LDH heterostructures could be attractive electrode materials as practical supercapacitors for next generation energy storage devices.