Electrochemical sensing of iron in aqueous medium using ZnO/rGO nanocomposite

Graphene Oxide (GO) was prepared via the modified Hummers’ method. The prepared GO was refluxed with zinc nitrate and hydrazine hydrate to obtain ZnO/rGO composite. UV-Vis, XRD, EDX, SEM, and FTIR spectroscopy were used to characterize the material. The characterization results verified the successful synthesis of the materials. The SEM images reveal wrinkled, crumbled rGO sheets, with rod-like fragments dispersed across the rGO surface. Cyclic voltammetry (CV) was performed in a 1 M KCl electrolyte containing different concentrations of ferric nitrate over a potential range of 0–1 V to evaluate the sensing performance of ZnO/rGO composite. Cyclic voltammetry of the bare electrode showed weak and poorly defined redox, whereas the ZnO/rGO-modified electrodes showed well-defined, enlarged anodic and cathodic peaks. The improved current response and sharp redox peak indicate that ZnO/rGO facilitates faster electron transfer and provides a larger electroactive surface area than the bare electrode. The further calibration plot reveals a moderate linear relationship, with a correlation coefficient (R²) of 0.95343. The ZnO/rGO modified electrode showed acceptable stability after 100 continuous segment CV cycles.