Impact of Addition of ZnO and CuO Colloidal Nanoparticles on the Physical Properties of the NiO Nanostructured Thin Film for Gas Sensing

This study used the sol–gel spin‐coating process to fabricate pure NiO films and NiO films incorporated with CuO and ZnO colloidal nanoparticles (NPs), which were synthesized by pulsed laser ablation in liquid (PLAL), for gas sensing applications. The structure, surface morphology, electrical characteristics and sensing capabilities of the resultant films were thoroughly examined for detecting nitrogen dioxide (NO 2 ) and hydrogen sulfide (H 2 S). X‐ray diffraction (XRD) analysis confirmed the crystallinity of the films, while atomic force microscopy (AFM) was employed to assess the surface morphology. Both pure and incorporated NiO films exhibited a polycrystalline cubic structure. Based on the AFM data, the roughness and grain size distribution decreased for the incorporated films. The band gap ( E g ) of the incorporated films decreased from 3.123 eV (for pure NiO) to 3.114 eV. Gas sensing tests revealed that incorporating ZnO and CuO NPs into the NiO films enhanced their gas sensing performance. The NiO films incorporated with ZnO exhibited the highest sensitivity to H 2 S gas, achieving 94% sensitivity after 150 s at 150°C, with a recovery time of 64 s. For NO 2 gas, the NiO films incorporated with ZnO and CuO showed the highest sensitivity at 200°C, reaching 70.9% sensitivity at 25 s, with a recovery time of 90 s.