Green Synthesis and Physicochemical Characterization of Copper Oxide Nanoparticles Mediated by Azadirachta indica A. Juss. Leaf Extract

Abstract

This study reports an eco-friendly and efficient method for the green synthesis of copper oxide nanoparticles (CuO NPs) using the aqueous leaf extract of Azadirachta indica A. Juss. Phytochemical profiling and GC–MS analysis of the extract revealed the presence of diverse bioactive compounds including fatty acid esters, alcohols, linoleic acid derivatives and andrographolide, which served as natural reducing and stabilizing agents during nanoparticle formation. The biosynthesized CuO NPs were characterized using UV–Vis, FTIR, XRD, FE-SEM, EDX, zeta potential and DLS analysis. UV–Vis spectroscopy confirmed nanoparticle formation with a characteristic absorption peak at 340 nm, attributed to electronic transitions in CuO nanoparticles. FTIR spectra verified the involvement of phenolics, flavonoids, terpenoids and other phytochemicals in reducing and capping the nanoparticles. XRD analysis confirmed the formation of highly crystalline monoclinic CuO phases. FE-SEM micrographs revealed spherical clustered nanoparticles with a mean size of 24.95 nm, while EDX confirmed high elemental purity containing only copper and oxygen. The zeta potential value of –21.4 mV indicated good colloidal stability due to biomolecule capping. The CuO nanoparticles exhibited a PDI value of 0.217, indicating monodispersity and acceptable colloidal stability of the dispersion. The findings demonstrate that A. indica leaf extract is an effective biological source for the green synthesis of stable CuO nanoparticles.