Investigation of the Structural, Phase Formation, Optical, Bias-Dependent Dielectric and Visible Region Photocatalytic Degradation Performance of Zn_1−xFe_xO Nanoparticles Prepared Using the Sol–Gel Method

This study involves the synthesis of Zn_1−xFe_xO (where x = 0, 0.01, 0.03, 0.05, 0.10 and 0.15) nanoparticles (NPs) using the sol–gel method and reveals the effect of Fe²⁺ and Fe³⁺ ion substitution on the structural and optical properties, photocatalytic degradation under visible light and the dielectric behavior of zinc oxide using x-ray diffraction, scanning electron microscopy, x-ray photoelectron spectroscopy, UV–visible spectroscopy and impedance analysis. The x-ray diffraction results show a wurtzite structure with average crystallite size varying between 40.74 nm and 22.46 nm in doped ZnO NPs. The optical study depicts a band-narrowing effect ranging from 3.19 eV to 2.87 eV for 15% Fe doping. Further, for 15% Fe doping, the dielectric constant decreases from 1490 to 98 at 10 kHz at 0 V and 25 V, respectively. Thus, the high dielectric constant of Fe-doped ZnO NPs makes it a suitable material for high-frequency electronic devices. Further, the absorbance study shows a high degradation rate constant of 1.36–0.86 h⁻¹ in the visible region for Fe doping concentrations varying from 0% to 15%, which indicates its use in environmental remediation applications.