pH reaction effect on biosynthesis of CuO/Cu2O nanoparticles by Moringa oleifera leaves extracts for antioxidant activities.

In this study, successfully investigated the biosynthesis of cupric oxide (CuO) and cuprous oxide (Cu₂O) nanoparticles using Moringa oleifera aqueous leaves extract. The effect of pH on the formation of copper oxide nanoparticles, the optical properties, and free radical scavenging activities was studied. The obtained nanoparticles were characterized using UV-Vis, FTIR, XRD, and SEM techniques. UV-Vis spectra showed a peak with strong absorption at 275 nm for copper oxide with a direct bandgap of 2.59–2.65 eV and an indirect bandgap of 1.74–1.87 eV. FTIR analysis revealed two distinct absorption bands at 511 and 528 cm⁻¹, which showed the successful production of copper oxide nanoparticles. The average crystallize size of copper oxide nanoparticles was 18–26 nm. It is clear from SEM images that CuO/Cu₂O NPs have, in general, a spherical morphology with particle sizes less than 80–100 nm. Interestingly, the prepared CuO/Cu₂O NPs showed high free radical scavenging activities. [ABSTRACT FROM AUTHOR]