Sunflower pollen-assisted synthesis of nanosized semiconducting ZnO and its application in the selective sensing of NO 2

Zinc oxide nanoparticles (ZnO NPs) were prepared by sunflower pollen-assisted sol–gel method and successive annealing treatment in air at 500 °C. The morphology and microstructure of the synthesized nanoparticles were characterized by means of SEM, XRD, BET surface area and XPS. Characterization data showed that sunflower pollen leads to the formation of zinc oxide microspheres constituted by an ensemble of crystalline ZnO nanoparticles of about 35 nm in diameter. ZnO NPs synthesized by this method have been used to fabricate a conductometric gas sensor which resulted highly sensitive and selective for the monitoring of low concentrations of NO 2 in air.