Green biosynthesis and physicochemical characterization of Fe₃O₄ nanoparticles using Punica granatum L. fruit peel extract for optoelectronic applications

Green biosynthesis of Fe₃O₄ nanoparticles (NPs) using plant extract is desired, as the plant extract is safe for humans and the environment. In this study, magnetite Fe₃O₄ NPs were greenly prepared using Punica granatum L. fruit peel extract as a reducing and capping agent. The effect of iron precursor contraction (0.01–0.1 M, FeCl₃) was studied. The Fe₃O₄ crystalline with an average crystallite size range from 21 to 23 nm was proven by X-ray powder diffraction. Scanning electron microscopy images showed that the synthesized Fe₃O₄ NPs were mostly cubical. Ultraviolet-visible spectra showed that the prepared Fe₃O₄ NPs exhibit absorption at 270 nm related to the Fe₃O₄ NPs with a direct bandgap ranging from 1.87 to 2.26 eV and indirect bandgap of 2.16–2.48 eV. Fourier transform infrared spectroscopy analysis showed two characteristic absorption bands at 515 and 567 cm⁻¹, which proved the successful formation of Fe₃O₄. The proposed method using Punica granatum L. fruit peel extract offers an economical and environmentally friendly route for synthesizing many other types of metal oxides.