Preparation of a novel hydrazine electrochemical sensor using Fe2O3@ZnO core-shell nanoparticles

Abstract

The sensitive and selective detection of hydrazine (HAZ) is crucial due to its high toxicity and widespread environmental impact. This work reports a green synthesis of spindle-shaped Fe₂O₃@ZnO core–shell nanoparticles using walnut shell as a sustainable biomass precursor via a combined wet impregnation–calcination approach. The core–shell architecture was fabricated through wet impregnation of pre-formed Fe₂O₃ cores followed by calcination, and thoroughly characterized by Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) mapping, and energy-dispersive X-ray spectroscopy (EDS). Electrochemical studies revealed that Fe₂O₃@ZnO exhibits superior activity for hydrazine oxidation, attributed to synergistic core–shell interactions that enhance electron transfer and increase active site density. The resulting sensor demonstrates excellent performance, featuring a wide linear range (0.02–68 µM), a low detection limit (14 nM), high sensitivity (3.54 µA/µM), and notable selectivity, stability, and reproducibility. These findings underscore the potential of biomass-derived core–shell nanomaterials for advanced electrochemical sensing.