A Novel Trace-Level Ammonia Gas Sensing Based on Flexible PAni-CoFeO Nanocomposite Film at Room Temperature.

In this study, we developed a new chemi-resistive, flexible and selective ammonia (NH) gas sensor. The sensor was prepared by depositing thin film of polyaniline-cobalt ferrite (PAni-CoFeO) nanocomposite on flexible polyethylene terephthalate (PET) through an in situ chemical oxidative polymerization method. The prepared PAni-CoFeO nanocomposite and flexible PET-PAni-CoFeO sensor were evaluated for their thermal stability, surface morphology and materials composition. The response to NH gas of the developed sensor was examined thoroughly in the range of 1-50 ppm at room temperature. The sensor with 50 wt% CoFeO NPs content showed an optimum selectivity to NH molecules, with a 118.3% response towards 50 ppm in 24.3 s response time. Furthermore, the sensor showed good reproducibility, ultra-low detection limit (25 ppb) and excellent flexibility. In addition, the relative humidity effect on the sensor performance was investigated. Consequently, the flexible PET-PAni-CoFeO sensor is a promising candidate for trace-level on-site sensing of NH in wearable electronic or portable devices.