Acetaldehyde detection using nickel-incorporated WO3 thin films prepared via spray pyrolysis Catalytic interplay and oxygen vacancy mediation on pristine and silver doped bismuth vanadate thin films for potential ammonia detection at room temperature

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 Ni2+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 acetal dehyde detection