Co₃O₄ nanoparticles synthesized with rotten-grape extract for use in supercapacitors and oxygen evolution devices

Phytochemicals in grape fruit juice have never been considered as potential sources of surface modification, shape modification, and energy storage. In our study, we demonstrate the hydrothermal synthesis of Co₃O₄ nanostructures from grape fruit extracts. X-ray diffraction analysis revealed that Co₃O₄ nanostructures exhibit a cubic phase, while Fourier transform infrared spectroscopy identified several functional groups. An analysis of Co₃O₄ nanostructures using a scanning electron microscope revealed that uniformly distributed nanoparticles of Co₃O₄ were trapped in the carbon content of the spices during calcination. UV–visible spectrometer analysis of Co₃O₄ nanostructures reveals a wide range of optical bands. It was found that one mL of grape fruit juice provided the lowest optical band gap of 2.51 eV for Co₃O₄ nanostructures. Nanostructures of Co₃O₄ were studied under alkaline conditions for use in supercapacitors and oxygen evolution reactions. An aqueous solution containing 1 mL of assisted Co₃O₄ nanostructures exhibited an overpotential of 290 mV at a current density of 10 mA cm⁻² in 1 M KOH. In addition, they showed a Tafel slope of 80 mV dec⁻¹. When dissolved in 3 M KOH electrolyte, grape fruit juice assisted Co₃O₄ nanostructures showed a specific capacitance of 867 F/g at 1.5 A/g in 3 M KOH aqueous solution. A specific capacitance retention percentage of about 101.1 % was achieved after 40000 galvanic charge-discharge cycles. It has been shown that the total photochemistry of biomass waste can be tuned and enhanced to enhance the functional properties of nanostructures derived from rotten grape fruit extract in order to develop functional materials with high performance for a wide range of applications.