Acetaldehyde detection using nickel-incorporated WO3 thin films prepared via spray pyrolysis

Acetaldehyde, a compound known for its cellular and genomic toxicity, poses a significant threat to both human health and environmental safety. This underscores the urgent need for cost-effective and highly sensitive sensors capable of detecting acetaldehyde at low concentrations. In this study, metal oxide semiconductor–based thin-film gas sensors were developed using pure and nickel-doped tungsten trioxide (WO₃). The thin films were fabricated via spray pyrolysis, a direct deposition technique that yielded crystalline monoclinic-phase WO₃ with a favourable surface morphology conducive to gas sensing. Among the samples, the 5 % Ni-doped WO₃ (WO₃:Ni-5) film exhibited the highest performance, delivering an impressive sensing response of 102.28 at room temperature. The enhanced response was attributed to the incorporation of Ni 2+ ions, which induced the growth of nanorods within a fibrous, flower-like microstructure, thereby increasing the active surface area. Comprehensive characterisation confirmed that the sensor has good selectivity towards acetaldehyde (25 S), sensitivity (5 ppm), repeatability, humidity tolerance, and long-term stability, establishing its strong potential for practical acetaldehyde detection. • Pure and nickel-doped WO₃ thin films were deposited via spray pyrolysis, exhibiting a crystalline monoclinic structure. • The incorporation of nickel dopant ·reduced the band gap and produced flower-like and rod-cluster surface structures in FE-SEM images. • The the improved surface roughness enhancing the gas adsorption. • The sensor demonstrated high sensitivity and a linear increase in sensor response towards acetaldehyde gas at room temperature (28 °C). • 5% Ni-doped WO₃ film (WNi-5) achieved a sensor response of S = 102.8 at 25 ppm acetaldehyde.