Trace-level ammonia detection at room temperature based on porous flexible polyaniline/polyvinylidene fluoride sensing film with carbon nanotube additives

Enhanced ammonia (NH3) sensing properties based on porous flexible polyaniline/polyvinylidene fluoride (PANI/PVDF) composite films, which used multi-wall carbon nanotubes (MWCNTs) as additives, were prepared by an in-situ polymerization process. The obtained flexible PANI/PVDF based sensing films showed a hierarchical porous structure, which enhanced their NH3 sensing performance. The results show that the addition of MWCNTs to the PANI/PVDF film further improved its stability and response to NH3. The response of the optimized MWCNT-PANI/PVDF film was found to increase by twofold to 33 %, and its recovery time was decreased 7-fold to 26 s than those of the PANI/PVDF sensing film for 1 ppm NH3 at 25 degrees C. Its lower detectable NH3 concentration was 0.1 ppm, with a response value of 8 % at 25 degrees C. Additionally, the MWCNT-PANI/PVDF film sensor presented good flexibility, showing only minor response value decline after 500 bending cycles. This work shows that the fabricated flexible MWCNT-PANI/PVDF film is promising for detecting trace-level NH3 gas at room temperature, and can be integrated with smart wearable devices for real-time environmental monitoring

Porous flexible polyaniline/polyvinylidene fluoride composite film for trace-level NH3 detection at room temperature

Flexible, highly sensitive, selective, and room temperature ammonia (NH3) sensor based on porous polyaniline/polyvinylidene fluoride (PANI/PVDF) composite film was developed by an in-situ chemical oxidative polymerization process. The obtained flexible PANI/PVDF film showed a three-dimensional and hierarchical porous structure, which greatly enhanced the sensing performance of the PANI film sensor. It exhibited an excellent selectivity to NH3 at 25 degrees C with 110% response towards 5 ppm. Furthermore, the PANI/PVDF film sensor can detect 1 ppm NH3 (Response = 27%) along with excellent stability and response reproducibility. To 0.2 ppm NH3, the PANI/PVDF showed 6.5% response at 25 degrees C. Furthermore, it also showed a good linearity relationship between the response and the concentration of NH3. Additionally, the PANI/PVDF film exhibited excellent bending stability, showing very little response value fluctuation at different bending angles. This work shows that the proposed PANI/PVDF film is promising for detecting trace-level NH3 at room temperature, and can be applied in real-time environmental monitoring. (C) 2020 Elsevier B.V. All rights reserved