Green synthesis of ZnO, CuO and NiO nanoparticles using Neem leaf extract and comparing their photocatalytic activity under solar irradiation

ABSTRACT

In this study, a facile, green, and eco-friendly approach was conducted for the synthesis of zinc oxide (ZnO), copper oxide (CuO), and nickel oxide (NiO) nanoparticles (NPs) using the leaf extract of the Azadirachta indica (neem) plant. The biosynthesized nanoparticles were characterized by X-ray diffraction (X-RD), Fourier transform infrared spectroscopy (FT-IR), energy dispersive x-ray (EDX), scanning electron microscopy (SEM), and ultraviolet–visible spectroscopy (UV-Vis). The X-RD showed that the synthesized ZnO, CuO, and NiO NPs were of high purity, mostly hexagonal, monoclinic, and cubic in shape, with an average crystalline size in the range 25.26–10.50 nm. The EDX confirms the presence of different elements: Zn, Cu, Ni, and O. Morphology of the nanoparticles was investigated with SEM. The presence of Zn-O, Ni-O, and Cu-O stretching vibration bands was revealed in FT-IR spectrum. The optical band gaps were in the range of 2.59–1.67 eV. The photocatalytic activity of NPs was evaluated by carrying out the degradation of methylene blue under solar irradiation. Among, the biosynthesized nanoparticles, CuO NPs showed excellent photocatalyst performance compared to ZnO and NiO NPs.

GRAPHICAL ABSTRACT

KEYWORDS:

• Green synthesis
• ZnO
• CuO
• NiO
• nanoparticles
• degradation
• methylene blue

Acknowledgments

In carrying out the research work regarding SEM, EDX, UV-Vis, FT-IR, and XRD analysis, the authors are thankful to the laboratory technical assistants of Addis Ababa Science and Technology University and Adama Science and Technology University.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability

All data generated or analyzed during this study are included in this article.

Additional information

Funding

This research did not receive any specific grants from funding agencies.