Tungsten (VI) Oxide Nanoparticles: Green Synthesis Using Petroselinum crispum Leaf Extract, Structural Characterization, and Gas Sensing Performance

Background: WO3 nanoparticles synthesized in a green way using plant materials are expected to exhibit unique properties controlled by the synergistic effects of the metal and plant constituents. Methods: Petroselinum crispum (parsley) leaf extract was used as a natural and renewable reducing and capping agent for the synthesis of WO3 nanoparticles. Results: X-ray diffraction analysis revealed that the WO3 nanoparticles had a monoclinic crystal structure with an average crystallite size of 20.3 nm, while energy-dispersive X-ray spectroscopy confirmed their high purity, and field-emission scanning electron microscopy revealed a rod-like morphology and controlled size distribution. The Raman spectrum of the nanoparticles showed strong peaks at 709 and 334 cm–1, confirming their monoclinic structure. The optical bandgap was calculated as 2.89 eV using ultraviolet–visible spectroscopy. Conclusions: The WO3 nanoparticles showed acceptable NO2 and NH3 sensing performances and exhibited optimal sensitivity at 100 and 200 °C, respectively, thus holding promise for gas sensor applications.