LAUSR

Abstract Iron oxide nanoparticles (IONPs) were successfully prepared by mixing iron (III) chloride (FeCl3) salt with henna leaf extract using a simple chemical method with and without applied pulsed laser ablation (PLA) (Nd-YAG). It was found that the bio-molecules inside the henna leaves extract played a significant role in converting the iron salts into IONPs. The PLA technique affected the size, shape, purity, and phases of iron oxide NPs from Fe2O3 to FeO. Fe2O3 and FeO NPs play a crucial role in the removal of methylene blue (MB) dye in water treatment. IONPs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet (UV–vis), and photoluminescence (PL) spectroscopy. XRD results showed a small crystallite size (50 nm) with hexagonal structure (hematite) forFe2O3 NPs without using PLA, while for FeO NPs prepared by PLA, the crystallite size was smaller (24 nm) and the diffraction peaks indicated a cubic structure with excellent crystal quality. SEM showed the grain size of Fe2O3 NPs was approximately 69.92 nm, while for the FeO NPs, it was approximately 56.60 nm when PLA was applied. UV–vis measurements indicated a blue shift for the energy gap value from 2.75 eV for Fe2O3 NPs eV to 3.3 eV for FeO NPs. PL spectroscopy revealed the band edge emission was approximately 3.57 eV for Fe2O3 NPs without PLA, while the band edge emission exceeded 3.63 eV for FeO NPs with PLA application. Moreover, the photocatalytic activity of NPs was demonstrated by the degradation of MB dye under average light irradiation. The results indicate that the synthesized FeO NPs prepared by PLA exhibited higher degradation efficiency, reaching 95 % at 50 min with high photocatalytic activity than the Fe2O3 without PLA, for which the degradation efficiency was 88 % at 70 min.