A Dual-Strategic Approach to Synthesize Fe2O3 Nanoparticles with Study on their Structural, Optical and Antibacterial Properties

In this study, iron(III) oxide (Fe2O3) nanoparticles were synthesized using two approaches namely a conventional chemical co-precipitation method and a green synthesis route utilizing Azadirachta indica leaf extract, which simultaneously functions as a reducing and stabilizing agent. Following synthesis, the nanoparticles underwent characterization to assess their optical behaviour along with structural and morphological features. Through XRD characterization, Fe2O3 was identified in its rhombohedral crystalline configuration, with average particle sizes measured as 42 nm for co-precipitation-derived samples and 35 nm for those synthesized via the green route. Scanning electron microscopy (SEM) revealed size variations between the two synthesis routes, with the green method producing relatively smaller and more uniformly dispersed nanoparticles. UV-Vis absorption spectra indicated the characteristic optical transitions with slight band gap variations, attributed to particle size and surface modifications by phytochemicals present in the neem extract. Fourier-transform infrared spectroscopy revealed characteristic Fe–O bond vibrations together with biomolecular groups in Fe2O3 nanoparticles produced via the neem-assisted route. Antimicrobial testing performed using the agar well diffusion method against Staphylococcus aureus and Escherichia coli showed that the green-synthesized particles achieved greater inhibition zones. This enhancement is associated with their nanoscale size, enlarged surface-to-volume ratio and the functional bioactive molecules originating from neem extract. Overall, the study underscores the potential of green synthesis for designing effective and biocompatible antibacterial nanomaterials.