Co3O4 spinel nanoparticles decorated graphite electrode: Bio-mediated synthesis and electrochemical H2O2 sensing

Abstract

The Co3O4 NPs were successfully synthesized by a green synthesis pathway using the analytes extracted from Sechium edule, the fruit of a perennial climber. The analytes, mostly, ascorbic acid, mediated CoOOH transformation to Co(OH)2 and, CoOOH was abundant with Co3O4 NPs in the control condition without these analytes. The structure and morphology of Co3O4 NPs were determined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Atomic force microscopy (AFM), Field emission scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Vibrating sample magnetometer (VSM). The pure Co3O4 NPs confirmed weak ferromagnetic properties. TEM images showed that the Co3O4 NPs have an average diameter size of 31.79nm. The Co3O4 NPs were tailored on a graphite electrode with an average concentration of 5.92×10−13mol/cm2 to develop a non-enzymatic H2O2 sensor in a phosphate buffer media (pH 7.2). The cyclic voltammetry (CV) technique within the −Ecat=0.5 to −0.5V vs. Ag/AgCl showed a low H2O2 reduction peak at −0.117V with a quasi-reversible electrochemical system. The modified electrode was exhibited a quick amperometric response (<5s), a low limit of detection (LOD) of H2O2 of 0.0217μM, and a high electrode sensitivity of 65.32nA/μM/cm2 and reproducibility (relative standard deviation 3.06%). No alteration of the amperometric responses was noted in the presence of common interferents.