Green Synthesis and Characterization of ZnO/α‐Fe₂O₃ Nanocomposites Using <scp><i>Hydrocotyle umbellata</i></scp> Leaf Extract and Evaluation of Their Antimicrobial Properties

Abstract

ABSTRACT In this study, ZnO/α‐Fe 2 O 3 nanocomposites were synthesized via a green coprecipitation method using Hydrocotyle umbellata leaf extract as a reducing and stabilizing agent. The synthesis involved Zn (NO₃)₂.6H₂O, ferric chloride, and sodium hydroxide in various molar ratios of ZnO/α‐Fe₂O₃ (9:1, 8:2, 7:3), followed by calcination at 400°C. The synthesized nanocomposites were analyzed using XRD, FTIR, UV‐Vis, and SEM to determine their crystalline structure, functional groups, optical properties, and surface morphology. The XRD analysis confirmed the formation of ZnO and α‐Fe₂O₃ phases, whereas FTIR confirmed the presence of metal‐oxygen bonds and phenolic compounds from the plant extract. UV‐vis analysis showed a redshift in the absorption spectra, indicating a reduction in bandgap energy in ZnO/α‐Fe₂O₃ nanocomposites compared to pure ZnO. The SEM results confirmed that the ZnO/α‐Fe 2 O 3 composites exhibit excellent crystallinity, with an average crystal size of approximately 39 nm, calculated using the Debye–Scherrer equation. The antimicrobial activity of ZnO/α‐Fe₂O₃ nanocomposites was evaluated using the disk diffusion method against Staphylococcus aureus , Escherichia coli , and Aspergillus niger . The ZnO/α‐Fe₂O₃ (8:2) formulation showed the strongest antibacterial effect against S. aureus , highlighting its potential for eco‐friendly antimicrobial applications.