Zinc oxide Nanoparticles, Biosynthesis, characterization and their potent photocatalytic degradation, and antioxidant activities

This study aimed to biosynthesize zinc oxide nanoparticles (ZnO-NPs) using the seed extract of Moringa oleifera. The catalytic activity of the biosynthesized ZnO-NPs was examined as photocatalyst for the degradation methylene blue (MB) and their antioxidant activity by H2O2 assay were studied. The biosynthesized ZnO-NPs and their physicochemical properties investigated via UV–visible spectroscopy (UV–vis), Fourier transform infrared (FTIR) spectroscopy, Transmission electron microscopy (TEM), energy dispersive X-ray (EDX), X-ray diffraction analysis (XRD) analysis, and zeta potential was calculated using the Zetasizer nano. UV–Visible analysis of the biosynthesized nanoparticles revealed the characteristic a specific peak at 375 nm indicating the formation of ZnO-NPs. XRD study showed a distinctive diffraction peak indicating the formation of crystalline nanoparticles which matches to the spherical and hexagonal structure of ZnO-NPs. TEM results confirmed the formation of spherical and hexagonal ZnO-NPs and the size ranging between 25 and 30 nm. EDX analysis was used for the determination of elemental composition of biosynthesized ZnO-NPs which included zinc, oxygen and carbon. FTIR spectroscopy is useful to determine the available functional group from the phytochemical components implicated in the stabilization and reduction of ZnO-NPs. ZnO-NPs exhibited effective photocatalytic activity in degrading methylene blue (MB) and maximum photocatalytic activity (71 %) after 24 hrs. In addition, ZnO NPs exhibited high antioxidant activity against H2O2 free radicals scavenger. The biosynthesized ZnO-NPs have excellent MB dye degradation power and complete dye degradation was achieved within 24 hrs and synthesized ZnO-NPs showed improved antioxidant power. ZnO-NPs are good tools for industrial applications.