Cost-effective preparation of cobalt oxide/nickel oxide composite for the efficient non-enzymatic electrochemical detection of uric acid

This study underscores the potential of Cucumis melo juice as a sustainable reducing, structure-directing, capping, and stabilizing agent used to modify the surface characteristics, shape, and size of nickel oxide (NiO) through a modified hydrothermal process. This modification results in a significant alteration of the optical band gap of NiO, which is subsequently utilized in combination with cobalt oxide (Co₃O₄) to synthesize Co₃O₄/NiO composites. The physical and optical properties of the synthesized materials, including their morphology, crystal structure, and optical behavior, were thoroughly examined using advanced analytical techniques, such as scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and UV-visible spectrometry, while the chemical bonds within these materials were investigated through Fourier transform infrared (FTIR) spectroscopy. Among the composites, the reduced Co₃O₄/NiO-1 composite, characterized by an optical bandgap of 2.07 eV, exhibited the most pronounced activity for electrochemical non-enzymatic detection of uric acid (UA). This particular composite demonstrated a broad operational range, capable of detecting UA at concentrations from 0.1 mM to 16 mM using the chronoamperometric method. Additionally, it achieved a high sensitivity of 7.63 × 10⁻⁴ µA mM⁻¹ cm⁻² and a low detection limit of 0.005 mM when tested in a 0.1 M phosphate buffer solution at a pH of 7.3.