Euphorbia hirta L. – mediated green synthesis of Fe, Ni and Fe-Ni alloy nanoparticles: Characterization and colloidal stability

The present investigation reports the eco-friendly synthesis of monometallic (Fe and Ni) and bimetallic (Fe–Ni) nanoparticles using aqueous leaf extract (ALE) of Euphorbia hirta (L.), a pantropical weed, from the tropical regions. The 0.1 M concentration of the metal precursors and the leaf extract were used to synthesis nanoparticles namely Fe NPs, Ni NPs and Fe–Ni NPs were characterized by analytical techniques including UV–vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), zeta potential analysis and dynamic light scattering (DLS). Fe, Ni NPs and Fe-Ni displayed at 280 nm, 380 nm and 340 nm, respectively during UV Visible spectra analysis. These results indicate that synthesized bimetallic nanoparticles are alloy type. FT-IR results showed that the biomolecules present in the ALE are responsible for reducing Fe 3 + and Ni 2+ ions into Fe° and Ni°, respectively as well as stabilizing the synthesized NPs. XRD measurements revealed that Fe, Ni, and Fe-Ni NPs are in FCC structure with the average crystalline size of 63, 61 and 56 nm respectively. The EDAX spectra reveal the distinctive peaks for Fe, Ni and Fe-Ni nanoparticles. The negative Zetapotential values of Fe (-0.672), Ni (-0.0733) and Fe-Ni (-0.0704) nanoparticles indicate the involvement of polyphenols in E . hirta causing repulsive forces within the NPs. Monometallic Fe, Ni and bimetallic Fe-Ni have polydispersity index of 0.412, 0.191 and 0.485, respectively which indicates the homogeneity nature of NPs. Overall, this study demonstrates an eco-friendly approach for synthesizing bimetallic Fe–Ni nanoparticles using E. hirta leaf extract. No biological or biomedical assay were performed. However potential biomedical applications will be focused in future after their toxicological evaluations.