In this study, silver/silver oxide nanoparticles (Ag/Ag2O NPs) were successfully biosynthesized using Phoenix dactylifera L. aqueous leaves extract. The effect of different plant extract/precursor contractions (volume ratio, v/v%) on Ag/Ag2O NP formation, their optical properties, and photocatalytic activity towards azo dye degradation, i.e., Congo red (CR) and methylene blue (MB), were investigated. X-ray diffraction confirmed the crystalline nature of Ag/Ag2O NPs with a crystallite size range from 28 to 39 nm. Scanning electron microscope images showed that the Ag/Ag2O NPs have an oval and spherical shape. UV–vis spectroscopy showed that Ag/Ag2O NPs have a direct bandgap of 2.07–2.86 eV and an indirect bandgap of 1.60–1.76 eV. Fourier transform infrared analysis suggests that the synthesized Ag/Ag2O NPs might be stabilized through the interactions of -OH and C=O groups in the carbohydrates, flavonoids, tannins, and phenolic acids present in Phoenix dactylifera L. Interestingly, the prepared Ag/Ag2O NPs showed high catalytic degradation activity for CR dye. The photocatalytic degradation of the azo dye was monitored spectrophotometrically in a wavelength range of 250–900 nm, and a high decolorization efficiency (84.50%) was obtained after 50 min of reaction. As a result, the use of Phoenix dactylifera L. aqueous leaves extract offers a cost-effective and eco-friendly method.

In this paper, ZnO nanoparticles (NPs) were greenly synthesized at different pH values of 4, 6, 9.5, and 11 via Portulaca oleracea leaf extract, and the effect of pH on the optical and structural properties was studied. UV-Vis spectrophotometers and FTIR spectroscopy characterized the optical properties. Meanwhile, the structural properties were characterized via Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). Furthermore, their photocatalytic dye degradation was examined against methyl orange dye. The characterization results have confirmed the successful biosynthesis of ZnO nanoparticles with a size ranging between 22.17 to 27.38 nm. The synthesis pH value significantly influenced ZnO NPs' optical and morphological properties. The results have also indicated the high performance of the greenly synthesized ZnO NPs for dye degradation.

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Green biosynthesis of Fe3O4 nanoparticles (NPs) using plant extract is desired, as the plant extract is safe for humans and the environment. In this study, magnetite Fe3O4 NPs were greenly prepared using Punica granatum L. fruit peel extract as a reducing and capping agent. The effect of iron precursor contraction (0.01–0.1 M, FeCl3) was studied. The Fe3O4 crystalline with an average crystallite size range from 21 to 23 nm was proven by X-ray powder diffraction. Scanning electron microscopy images showed that the synthesized Fe3O4 NPs were mostly cubical. Ultraviolet-visible spectra showed that the prepared Fe3O4 NPs exhibit absorption at 270 nm related to the Fe3O4 NPs with a direct bandgap ranging from 1.87 to 2.26 eV and indirect bandgap of 2.16–2.48 eV. Fourier transform infrared spectroscopy analysis showed two characteristic absorption bands at 515 and 567 cm−1, which proved the successful formation of Fe3O4. The proposed method using Punica granatum L. fruit peel extract offers an economical and environmentally friendly route for synthesizing many other types of metal oxides.

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