Improved Structural and Electrochemical Properties of Mg-Doped Nickel Cobaltite Nanoparticles Synthesized Using Low-Temperature Microwave Hydrothermal Method

The specific capacitance of materials influences the energy storage capacity. A series of Mg x Ni 1-x Co 2 O 4 ( x = 0.0 - 0.1) nanoparticles using the low-temperature microwave-hydrothermal (M-H) method at 160 0 C temperature, and sintered at 600 °C. The samples were then characterized using X-ray diffraction (XRD), Field Emission Scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). It is observed from X-ray diffraction that all the samples are cubic spinel in nature with space group Fd-3m, and the lattice parameter varies between 8.097 ( x = 0.0) and 8.083 ( x = 0.10). The nanoparticles have a hexagonal nanoflake-like shape morphology with an average particle size of 180 nm to 350 nm. The tetrahedral and octahedral absorption bands were observed at 561 cm -1 and 654 cm -1 , respectively. The valence states of Ni 2+ /Ni 3+ , Co 2+ /Co 3+ , and Mg 2+ were confirmed by X-ray photoelectron spectroscopy. The electrochemical studies using CV and GCD were performed on all the samples. High values of specific capacitance of 332 F g −1 , energy densityof 9.05 Wh kg -1 , and power density of 224.84 W kg -1 were observed for the sample x = 0.08. Therefore, Mg 0.08 Ni 0.92 Co 2 O 4 sintered at 600 °C shows good impedance and electrochemical properties, which are helpful for supercapacitor applications. Figure 1