Microwave-assisted synthesis of nickel-oxide/cobalt-oxide/reduced graphene oxide nanocomposite for highly sensitive electrochemical determination of epicatechin in food samples

The determination of bioactive compounds in food samples has received significant attention in recent years due to their potential health benefits. Epicatechin (EC) is one of the flavanol compounds naturally present in various foods such as tea, cocoa, grapes, and berries. It has various potential health benefits, including antioxidant, antiinflammatory, and anti-cancer properties. However, excessive intake of EC can also have negative effects on health. The accurate and reliable detection of EC in food samples is crucial for ensuring consumer safety and maintaining quality control standards in the food industry. Therefore, developing a sensitive and reliable sensor for detecting EC in food samples is of significant importance. This research presents a novel method for detecting EC in various food samples. The method involves the use of a nickel-oxide/cobalt-oxide/reduced-graphene-oxide composite material (NiO/CoO/rGO) synthesized through a microwave-assisted technique which is then applied to a glassy carbon electrode to fabricate NiO/CoO/rGO/GCE sensor for sensitive determination of EC. The structural, morphological, and electrochemical characteristics of the electrode materials were analyzed using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) spectroscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The morphological results confirmed the formation of well-dispersed NiO/CoO nanoparticles on the surface of rGO sheets. The electrochemical results revealed that the NiO/CoO/rGO/GCE sensor has exceptional electron-transport properties and electrocatalytic activity towards EC, with an Rct value of 90.85 k omega that is lower than that of the Bare/ GCE and GO/GCE electrodes, which attributed to the synergistic effect of NiO/CoO nanoparticles and rGO sheets. The method was found to have a detection limit of 0.0012 mu M for EC, with a linear range of 0.05-65 mu M. The sensor was also reliable, stable, reproducible, and selective, and yielded excellent recoveries (near to 100 %) with low RSD values for detecting EC in food samples.