UV-activated polyaniline/tungsten oxide double-layer for enhanced ammonia gas sensor at room temperature

Abstract Recent advancements in non-destructive testing methods have significantly improved the early and straightforward diagnosis of diseases. The detection of ammonia gas at low concentrations in human breath serves as a vital indicator for health analysis. In this study, a UV-activated ammonia gas sensor based on a polyaniline-tungsten oxide (PANI-WO 3 ) double-layer was developed and evaluated. The synthesized WO 3 and its composite were characterized using field-emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques to confirm their structural and morphological properties. The electroplated gas sensor exhibited high sensitivity and excellent selectivity toward ammonia gas at room temperature. The conductivity variations of the sensor were systematically investigated under both dark and ultraviolet (UV) light irradiation. The results revealed that UV irradiation significantly enhanced the sensor’s performance, reducing the detection limit by a factor of 10 and improving the sensor response by a factor of 3.42 for 10 ppmv NH 3 . Moreover, UV irradiation reduced the response time by 37.32.% and the recovery time by 27.27%, demonstrating its effectiveness in enhancing the dynamic performance of the sensor. This study highlights the potential of UV-activated PANI-WO 3 double-layer as promising candidates for room-temperature gas sensors, offering high sensitivity, selectivity, and rapid response for applications in non-invasive health diagnostics.