Synergistic design of NiO/CuO/Co3O4 ternary nanocomposite for high-efficiency supercapacitors

NiO/CuO/Co3O4 ternary nanocomposites (TNCs) were synergistically designed via hydrothermal method to enhance interfacial charge transfer and redox activity for high-efficiency supercapacitor applications. The structural analysis using XRD confirmed the coexistence of cubic NiO, monoclinic CuO and spinal Co3O4 phases with an average crystallite size of ~ 21 nm, indicating the formation of a well-defined ternary system. XPS analysis verified the presence of Ni2+/ Ni3+, Cu2+ and Co2+/Co3+ oxidation states along with oxygen vacancies. FESEM and HRTEM studies revealed a hexagonal plate-like morphology with well-defined lattice fringes and polycrystalline nature of the prepared material. BET analysis showed a high specific surface area of 131 m2g− 1 with mesoporous structure (~ 1.93 nm pore size), facilitating efficient electrolyte access and charge transport. Electrochemical measurements demonstrated excellent pseudocapacitive behaviour with a high specific capacitance of 1523 F g− 1 at 10 mV s− 1 scan rate and 1160 F g− 1 at 2 A g− 1 current density from CV and GCD curves, respectively. The electrode exhibited superior cyclic stability with 97.8% capacitance retention after 1000 cycles at 5 A g− 1. A symmetric supercapacitor device was fabricated, delivering a specific capacitance of 395 F g− 1 at 10 mV s−1and an energy density of 69.7 Wh kg− 1. The device also demonstrated practical applicability by successfully powering a red LED. These results highlight the potential of the NiO/CuO/Co3O4 TNCs as an efficient electrode material for next-generation high energy supercapacitors.