Environmentally friendly synthesis of Ag–ZnO nanocomposite-modified graphite electrode for copper ion quantification

Abstract

The proposed work aims at toxic copper ion quantification in aqueous media using nanocomposite biosynthesized by halim seed extract. Here, Ag–zinc oxide (H–Ag–ZnO) nanocomposite was prepared by halim-mediated simple co-precipitation method. The crystallinity, morphology, lattice structure, absorption study, and functional bonds were observed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), ultraviolet (UV)–vis spectroscopy, and Fourier transform infrared spectroscopy (FTIR). The prepared nanosensor was drop casted on a disposable graphite electrode to evaluate its sensing behavior in KCl with ferri/ferrocyanide solution using voltammetry and obtained superior response. The cyclic voltammetry of sensor in ferrocyanide solution showed the oxidation peak in the existence of concentration of Cu²⁺ ions with magnified responses at different scan rates. The differential pulse voltammetry (DPV) results were obtained after preconcentration using chrono deposition at − 400 mV. The optimum peak was attained at a deposition time of 120 s and pH 7.5. The calibration graph from DPV analysis of copper ions yielded a correlation efficient (R²) = 0.99, detection limit (LOD) of 7.47 ppb, and quantification limit (LOQ) of 22.64 ppb with a linear range of 10–100 ppb.