Nickel oxide doping impact on the NO2 sensing properties of nanostructured zinc oxide deposited by spray pyrolysis

In this study, zinc oxide was doped with varying Nickel oxide nanostructured thin film concentrations using spray pyrolysis at 400 °C. At low Ni content, the ZnO phase exhibited polycrystalline structures, whereas a high Ni concentration resulted in the development of an additional NiO phase. The morphological analysis indicates the presence of nano-spherical structures at lower Ni concentrations, with nanoflakes embedded at varying orientations. The density of the nanoflakes structure was observed to increase as the Ni content was increased, enhancing the surface-to-volume ratio, which has potential applications in gas sensing. The highest sensitivity was detected for the sample doped with the highest Ni content, which can be attributed to its superior effective surface area. The optimal sensitivity was 45.26% at 200 °C.