One-step preparation of flexible citric acid-doped polyaniline gas sensor for ppb-level ammonia detection at room temperature

In this work, a citric acid-doped polyaniline/polyvinylidene fluoride (CPP) flexible ammonia sensor was prepared by in situ oxidative chemical polymerization on a flexible porous polyvinylidene fluoride membrane. The CPP sensor exhibited excellent performance at room temperature (217% response for 1 ppm NH3), low detection limit (LOD) reaches 3 ppb, and rapid response and recovery times (30 s /195 s for 1 ppm NH3, respectively). Furthermore, the sensor shows outstanding flexibility and excellent stability. After 10,000 bending cycles, the CPP sensor still produces over 99% stable response. The response reached 95% of its initial value after more than 60 days of storage. The CPP sensor exhibits excellent gas-sensing performance for ammonia gas, mainly attributed to the increase in active sites induced by citric acid doping and the synergistic effect of the porous substrate. The above results demonstrated that the CPP flexible film sensor is a high-performance candidate for enhanced ammonia gas sensing properties at room temperature.