Green Synthesis of Iron Oxide Nanoparticles Using Melastoma malabathricum Leaf Extract for Photocatalytic Degradation of Methylene Blue and Antibacterial Activity

In this study, iron oxide nanoparticles (IONPs) were synthesized via a green route using Melastoma malabathricum leaf extract and ferric chloride hexahydrate under ambient conditions. X‐ray diffraction (XRD) confirmed the crystalline, mixed‐phase structure of the nanoparticles with an average crystallite size of 17.19 nm. UV–Vis spectroscopy revealed absorption peaks at 266 and 374 nm, corresponding to direct and indirect band gaps of 2.12 and 1.26 eV, respectively. Fourier transform infrared (FTIR) analysis indicated Fe–O stretching vibrations peaks at 451, 538, and 679 cm −1 , while field emission scanning electron microscopy (FESEM) showed nanoparticle morphology. Energy dispersive X‐ray (EDX) analysis confirmed the presence of Fe and O elements. Photocatalytic studies demonstrated methylene blue degradation efficiencies of 64.44% without H 2 O 2 and 91.36% with H 2 O 2 after 210 min of natural sunlight irradiation. In contrast, antibacterial assays against Staphylococcus aureus , Klebsiella pneumoniae , Escherichia coli , and Shigella sonnei showed no significant inhibitory effect. This study demonstrates a cost‐effective, eco‐friendly synthesis of IONPs and highlights their potential for application in wastewater remediation through photocatalytic oxidation.