The low-cost synthesis of Fe₂O₃ nanoparticles by sol-gel method: an avenue to easier optical and biomedical applications

Iron oxide (Fe₂O₃) nanoparticles were successfully synthesized using a cost-effective sol-gel method, starting from iron(II) chloride (FeCl₂) as the precursor. The synthesis process involved controlled hydrolysis and condensation followed by drying at 100°C and calcination at 600°C to yield a crystalline nanopowder. Structural analysis using X-ray diffraction (XRD) revealed a polycrystalline material with prominent diffraction peaks corresponding to a rhombohedral phase (R3c space group), consistent with hematite (α-Fe₂O₃), and confirmed by comparison with JCPDS card no. 01-073-0548. Crystallite sizes, calculated using Scherrer’s equation, ranged from 18 to 34 nm with an average of approximately 27.33 nm, indicating nanocrystalline domains with high crystallinity. Fourier Transform Infrared (FTIR) spectroscopy confirmed the presence of Fe–O vibrational bands and surface hydroxyl groups, supporting the formation of iron oxide and indicating residual adsorbed water. Optical properties analyzed by UV-Vis spectroscopy revealed a band gap of 2.71 eV, placing the material in the wide-bandgap semiconductor category, suitable for photocatalytic and optoelectronic applications. Antibacterial activity against Escherichia coli was assessed using the agar diffusion method, with inhibition zones of 15 mm and 18 mm observed for 0.03 g and 0.05 g Fe₂O₃ dispersions, respectively. Statistical analysis via one-way ANOVA confirmed the dose-dependent efficacy, though the inhibition was slightly lower than that of a standard antibiotic (22 mm, gentamicin). The discovery proves the possible use of sol-gel manufactured Fe₂O₃ nanoparticles for antimicrobial coatings, environmental cleanup, and nanomedicine because of their stable structural, optical, and bioactive features.