Polyaniline (PANI) functionalized multiwall carbon nanotubes (MWCNTs) were prepared via in situ chemical polymerization process of aniline, in which MWCNTs were spray coated on the fabric for wearable ammonia sensor. Structural, morphological, thermal properties and wettability were analyzed by scanning electron microscope, X-ray diffraction, Raman analysis and contact angle measurement. No substantial change in base resistance of MWCNTs/PANI fabric sensor was observed for a wide range of bending (from 90° to 270°) shows excellent wearability. The sensors were exposed to 20-100 ppm ammonia vapor at room temperature. It was observed that the sensing response of PANI coated MWCNTs was enhanced than MWCNTs and PANI. The sensor has the capability to detect ammonia with high sensitivity (92% for100 ppm), excellent selectivity quick response (9 s), and recovery time (30 s). The lower detection limit (LOD) for the MWCNTs/PANI fabric sensor was found to be 200 ppb. The influence of humidity on sensing parameters was studied. Sensing response and resistance of sensor have shown excellent stability after one month. We observed that PANI have a dual role in enhancing flexibility as well as improve the sensor performance toward ammonia. The results reveal the potential application of fabric based sensor for monitoring NH gas under ambient conditions.

No abstract

No abstract

No abstract

The present work reported the polyaniline (PANI) and multiwalled carbon nanotube (MWCNT)-based nanocomposite as a sensing material for the determination of aqueous ammonia by the enhanced fluorescence method. The excitation wavelength-dependent photoluminescence (PL) intensity has shown dual emission peaks at 340 and 380 nm that correspond to two different excitation energy states. The pH-based PL intensity and zeta potential variation were analyzed to optimize the suitable medium for aqueous ammonia sensing. Zeta potential was found to shift from 4 to −21 mV upon changing the pH of the the solution from acidic to alkaline medium. The fluorescence intensity of PANI/MWCNTs was found to increase upon increasing the pH from 3.0 to 6.0 (acidic region) and exhibits a plateau upon further increasing the pH from 7.0 to 12 (basic region). The PANI/MWCNT composite has shown a linear response to aqueous ammonia concentration varying from 25 to 200 μM with a correlation coefficient (R 2) of 0.99 and a limit of detection of 15.19 μM. The presence of relevant interference molecules and physiological ions had no influence on the detection of aqueous ammonia. Field-level study demonstrated that the level of aqueous ammonia can be determined selectively by using the PANI/MWCNT composite for various applications. The mechanism for the selective detection of aqueous ammonia is deliberated in detail.