Synthesis, characterization and dielectric properties evaluation of NiO-Co₃O₄ nanocomposite

Nanosized materials are increasingly being recognized as inherent components in the development of energy storage devices and other state-of-the-art dielectric applications. In this work, nickel oxide (NiO), cobalt oxide (Co₃O₄) and NiO–Co₃O₄ nanocomposites in different compositions (10%, 20%, 30% and 40%) were successfully synthesized through hydrothermal method, optimizing concentrations of the precursors, and X-ray diffraction confirmed single-phase polycrystalline NiO and Co₃O₄. SEM images showed that distinct morphologies for each material and FTIR spectra reveal Ni–O and Co–O. UV–visible analysis shows a plasmon peak at 307 nm for NiO and excition absorption at 282 nm for Co₃O_4. NiO–Co₃O₄ nanocomposites displayed band gaps ranging from 2.37 eV to 2.67 eV. Dielectric properties showed a decrease in εʹ with frequency, attributed to Maxwell–Wagner and hopping models. AC conductivity increased with frequency due to Co₃O₄ content and oxygen vacancies. The study suggests potential applications in supercapacitors, spintronics, high-frequency devices and ultra-high dielectric materials.