Electronic and structural disorder of NiCo2O4 nanostructures using phytochemicals from desert gourd offered efficient asymmetric supercapacitor and oxygen evolution reaction

Abstract

In this study, we have utilized the raw material of desert gourd fruit juice which distributed in the wide range of desert areas of the world. The desert gourd juice carries a significant content of acidic compounds which can slightly decrease the pH of growth solution, hence it could impart a significant role in the morphological transformation. Also, the purpose of using desert gourd fruit juice was the availability of rich amount of green reducing, capping and stabilizing agents for obtaining the short range and closely packed nanoparticles of NiCo2O4. The preparation of nanostructured NiCo2O4 materials was carried out by using desert gourd fruit juice through hydrothermal process followed by thermal annealing in air. The morphology, crystalline structure, surface chemical composition and localized atomic investigations were performed by several analytical techniques. The role of desert gourd fruit juice on the structural and functional features of NiCo2O4 was also explored. The desert gourd juice through the decrease in the pH of growth solution and carrying green reducing, capping and stabilizing agents originating closely packed NiCo2O4 nanoparticles instead of nanorod like morphology. The oxygen evolution reaction (OER) half-cell characterization demonstrated overpotential of 260 mV@10 mAcm−2, Tafel slope of 62 mV dec−1 and durability of 40 h using NiCo2O4 nanostructures prepared with 2 mL of desert gourd juice. Moreover, energy storage aspects of NiCo2O4 nanostructures prepared with desert gourd juice were studied for supercapacitor application and an asymmetric supercapacitor (ASC) was developed. The findings of presented study revealed a high specific capacitance (Cs) 1958.17 F/g for newly developed ASC and high retention percentage of 99–90 % during cycling stability was also notice. The enhanced performance of as prepared NiCo2O4 nanostructures are attributed from the formation of unique architecture, surface oxygen vacancies, high ionic diffusion, high exposure of surface active sites, fast electron communication, swift charge transport at the interface between electrode and electrolyte.