Green Synthesis and Comprehensive Characterization of Zinc Oxide Nanoparticles Using Alternanthera sessilis Leaf Extract

Abstract

Green synthesis of metal oxide nanoparticles using plant extracts has emerged as an environmentally friendly alternative to conventional chemical methods. In the present study, zinc oxide (ZnO) nanoparticles were synthesized using the aqueous leaf extract of Alternanthera sessilis. Preliminary phytochemical screening confirmed the presence of flavonoids, terpenoids, anthraquinones, and glycosides, which acted as reducing and stabilizing agents during nanoparticle synthesis. The synthesized ZnO nanoparticles were characterized using UV–Visible spectroscopy, FTIR, XRD, FESEM-EDAX, HRTEM, dynamic light scattering (DLS), and zeta potential analyses. The UV–Visible spectrum exhibited strong absorption in the ultraviolet region, confirming the semiconducting nature of ZnO nanoparticles. FTIR analysis revealed hydroxyl, carbonyl, and other oxygen-containing functional groups involved in nanoparticle formation and stabilization. XRD analysis confirmed the formation of highly crystalline hexagonal wurtzite ZnO with an average crystallite size of 22.8 nm. FESEM and HRTEM analyses showed predominantly spherical to quasi-spherical nanoparticles with particle sizes ranging from 3–35 nm. EDAX confirmed zinc and oxygen as the major constituent elements, indicating high purity of the synthesized nanoparticles. DLS and zeta potential analyses demonstrated moderate colloidal stability with particle aggregation in aqueous suspension. The results demonstrate that A. sessilis leaf extract is an effective natural reducing and capping agent for the eco-friendly synthesis of crystalline ZnO nanoparticles with promising potential for photocatalytic and biomedical applications.