NO2 sensing properties of N-, F- and NF co-doped ZnO nanoparticles

Zinc oxide nanoparticles (ZnO NPs) doped with N and F ions were prepared by a simple sol-gel technique in the presence of various additives. The morphology and microstructure of the synthesized nanoparticles were characterized by means of SEM, XRD, BET surface area, UV–Vis-DRS, micro-Raman and photoluminescence. Characterization data highlighted the microstructural changes subsequent to introduction of the dopants into the lattice structure of ZnO nanoparticles. Conductometric gas sensors based on the N-doped ZnO, F-doped ZnO and NF co-doped ZnO NPs synthesized were fabricated and tested in the monitoring of low concentrations of NO2 in air. The effect of the different dopants on the sensing properties have been investigated and correlated with the morphological and microstructural characteristics. The impact of UV–Vis irradiation (λ = 400 nm) on the sensors performances was also studied. Results obtained have demonstrated that N-doped ZnO sensor displays the best NO2 sensing performances in dark and furthermore can be activated under UV–Vis irradiation to operate effectively at room temperature (RT).