Effect of synthesis route on the morphology and thermal stability of zno nanoparticles

Abstract

Zinc oxide nanoparticles (ZnO NPs) were synthesized through three distinct routes: green synthesis using Balanites aegyptiaca seed coat extract (BZN), green synthesis using walnut shell extract (WZN), and conventional aqueous precipitation (AZN). The objective was to evaluate the influence of the synthesis pathway on nanoparticle morphology and thermal stability. Transmission electron microscopy (TEM) analysis revealed that the BZN sample exhibited the finest and most uniformly dispersed particles, with mean diameters in the range of 20 to 50 nm and predominantly spherical to quasi spherical morphologies. The AZN sample displayed irregular shapes and pronounced aggregation, while the WZN nanoparticles showed moderate clustering with distinguishable individual particles in the range of 25 to 60 nm. Thermogravimetric analysis (TGA) indicated that the WZN sample possessed the highest thermal stability, exhibiting the lowest total weight loss across the examined temperature range. The BZN sample demonstrated a notable multi stage weight loss attributed to the decomposition of surface bound phytochemicals, whereas the AZN sample showed relatively fewer decomposition stages owing to the absence of biological stabilizing agents. Derivative thermogravimetric (DTG) analysis further confirmed the presence of distinct decomposition events in the green synthesized samples. The findings demonstrate that plant mediated synthesis routes, leveraging agricultural waste materials, offer an environmentally sustainable approach to producing ZnO nanoparticles with tuneable morphological and thermal characteristics suitable for applications in catalysis, antimicrobial materials, and environmental remediation.