Study of the physical properties of NiO nanoparticles synthesized from the flowers, seeds, and leaves extracts of Moringa oleifera

Three aqueous solutions from the flowers, seeds, and leaves (f-s-l) of Moringa oleifera (M.O) were used as effective chelating and/or reduction/oxidizing agents for the biosynthesis of nickel oxide nanoparticles NiO-NPs (NiO@flowers, NiO@seeds, and NiO@leaves). The structural properties were characterized via X-ray diffraction, Fourier-transform infrared spectroscopy, and Raman spectroscopy. All particles crystallized in a face centered-cubic single Bunsenite phase. NiO@flowers presented the lowest average crystallite size of 18.5 nm compared to 29.0 nm for NiO@seeds and 21.7 nm for NiO@leaves. Their band gap determined using diffuse reflectance UV-Visible and confirmed by photoluminescence analysis was found to be 3.42 eV for all the annealed samples. While morphology analysis from scanning electron microscopy revealed that NiO@flowers nanoparticles displayed a non-uniform morphology with spherically agglomerated nano-crystals, which are flat and more compact. The NiO@seeds nanoparticles exhibited highly coalescent nanograins while the NiO@leaves show irregularly connected microcavities with small nanograins.

Automated summary

Three aqueous solutions derived from Moringa oleifera (M.O) flowers, seeds, and leaves were used for the biosynthesis of nickel oxide nanoparticles (NiO-NPs). These nanoparticles were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and Raman spectroscopy, and were found to crystallize in a face centered-cubic single Bunsenite phase. NiO@flowers had the smallest average crystallite size of 18.5 nm, while NiO@seeds had 29.0 nm and NiO@leaves had 21.7 nm. Scanning electron microscopy revealed that NiO@flowers had non-uniform, spherically agglomerated nano-crystals, while NiO@seeds had highly coalescent nanograins and NiO@leaves had irregularly connected microcavities with small nanograins.