Hydrothermal synthesis of NiCo₂O₄–NiO nanorods for high performance supercapacitors

In this work, spinel-metal oxide (NiCo₂O₄–NiO) nanorods based electrode was fabricated and tested for their efficacy as supercapacitors. The NiCo₂O₄–NiO was synthesized by hydrothermal method and characterized using thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and transmission electron microscope (TEM) respectively. The TEM images reveal the morphology of the synthesized metal oxides in the form of nanorods with length of several micrometers and diameter in the range of 60–70 nm. The XRD pattern confirmed the formation of cubic spinel structure. A three electrode cell set up was employed to estimate the electrochemical performance of the material. It is observed that the NiCo₂O₄–NiO showed specific capacitance of 490 F/g at 0.5 A/g as compared to pure NiCo₂O₄ which is around 216 F/g at 0.5 A/g. The enhanced capacitance mainly arises from the incorporation of NiO secondary phases within the spinels which increases the number of redox active sites. The present work proves to be a promising strategy to improve the performance of the electrode material for supercapacitors.