Structural modification of ZnO@Ag2O nanostructures functionalized on optical fiber for room-temperature acetone detection with sub-ppm sensitivity.

In this work, a high-performance, room-temperature-operated acetone gas sensor is developed based on cladding-modified optical fiber functionalized with hierarchical flower-like ZnO@Ag2O nanostructures. Unlike conventional metal-oxide gas sensors operating at elevated temperatures, the formation of a p-n heterojunction between p-type Ag2O and n-type ZnO facilitates efficient charge separation and significantly lowers the activation energy for acetone oxidation, enabling enhanced sensing at ambient conditions. The structural and morphological properties were characterized by X-ray diffraction, FESEM, XPS, and FTIR. The sensing performance was achieved by coating the modified fiber cladding with ZnO@Ag2O, where evanescent-field interaction and adsorption-induced optical property changes govern the sensing mechanism, as validated by COMSOL Multiphysics simulations. The flower-like morphology provides a larger surface area and abundant active sites, resulting in superior sensing performance compared to pristine ZnO nps. The performance parameters of the developed sensor include a sensitivity of 11.37/ppm, a limit of detection of 0.85 ppm, and response and recovery times of 14 s and 60 s, respectively, compared to pristine ZnO nps. Additionally, the sensor exhibits good selectivity for acetone over different interfering VOC species. Owing to its spark-free operation, low power consumption, and immunity to electromagnetic interference, the proposed sensing platform presents a promising solution for real-time acetone detection in industrial process monitoring and non-invasive biomedical diagnostics.