Facile Synthesis and Antifungal Efficiency of Nickel and Zinc Oxide Nanoparticles

Nickel oxide (NiO) and Zinc oxide (ZnO) nanoparticles were synthesized using a simple, eco-friendly co-precipitation method followed by ultrasonication. The synthesis utilized AR-grade NiCl₂·6H₂O and Zn(NO₃) ₂·6H₂O with NH₄OH as a precipitating agent, offering a cost-effective and scalable approach. Structural analysis via X-ray diffraction (XRD) confirmed the formation of pure cubic phases with crystallite sizes ranging between 10.4–18.5 nm for NiO and 11.6–19.2 nm for ZnO, depending on the calcination temperature (400–600°C). UV–Vis spectroscopy revealed a tunable band gap: NiO exhibited Eg values of 4.1 eV (500°C) to 1.6 eV (600°C), while ZnO showed Eg from 3.6 eV (500°C) to 4.0 eV (600°C), indicating potential for visible-light-driven photocatalytic or optoelectronic applications. FTIR confirmed strong metal–oxygen bonding, and SEM revealed well-defined porous morphologies. Notably, antifungal activity tested against Aspergillus niger and Fusarium spp. using the Kirby–Bauer method showed zone of inhibition (ZOI) up to 17.4 mm for ZnO and 16.6 mm for NiO, respectively, at a nanoparticle concentration of 200 µg/ml. This study is innovative in demonstrating a temperature-tuned synthesis approach that correlates nano-structural features with antimicrobial efficiency, enabling design of next-generation biocompatible antifungal agents for biomedical coatings and environmental remediation.