Microwave-assisted hydrothermal synthesis of spinel nickel cobaltite and application for supercapacitors

A novel method has been developed in this study for preparation of the spinel nickel cobaltite (NiCo2O4) nanoparticles. The workflow comprises a microwave-assisted hydrothermal process using nickel nitrate hexahydrate and cobalt nitrate hexahydrate as precursor and urea as hydrolysis-controlling agent, followed by calcination. First, the needle-like nickel carbonate hydroxide hydrate and cobalt basic carbonate are obtained by microwave-assisted hydrothermal process under 800 W microwave irradiated for 5 min. Then, the needle-like nickel carbonate hydroxide hydrate and cobalt basic carbonate composites are calcined at 400 °C for 2 h to fabricate NiCo2O4 nanoparticles. The NiCo2O4 nanoparticles show a high-specific capacitance of 332.8 F/g under a mass loading of 2 mg/cm within −0.5 and 0.5 V at a scan rate of 100 mV/s in a 0.5 M H2SO4 solution. The NiCo2O4 is analyzed and characterized by X-ray power diffraction (XRD), transmission electron microscopy (TEM), infrared spectroscopy (IR), and cycle voltammograms (CV).

► NiCo2O4 nanoparticles used in supercapacitors by microwave-assisted hydrothermal method.
► Prepare nanocrystalline oxides in very shorter durations.
► NiCo2O4 nanoparticles have high-specific capacitance.