Hydrothermal and soft-templating synthesis of mesoporous NiCo₂O₄ nanomaterials for high-performance electrochemical capacitors

Abstract

Mesoporous nickel cobaltite (NiCo₂O₄) nanoparticles were synthesized via a hydrothermal and soft-templating method through quasi-reverse-micelle mechanism. The physicochemical properties of the NiCo₂O₄ materials were characterized via X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectra, and nitrogen sorption isotherms measurements. The electrochemical performances of the NiCo₂O₄ electrode were investigated by cyclic voltammetry, chronopotentiometry, and electrochemical impedance spectroscopy tests. The obtained NiCo₂O₄ materials exhibit typical mesoporous structures, with an average particle size of about 200 nm, a specific surface area of 88.63 m² g⁻¹, and a total pore volume of 0.337 cm³ g⁻¹. The facile electrolytes penetration for the mesoporous structures favors high-performance of the NiCo₂O₄ electrode. The NiCo₂O₄ electrode shows a high specific capacitance (591 F g⁻¹ at 1 A g⁻¹), high-rate capability (248 F g⁻¹ at 20 A g⁻¹), and a good cycling behavior for tested 3,000 cycles, indicating a promising application for electrochemical capacitors.