Chemiresistive ammonia gas sensor based on branched nanofibrous polyaniline thin films

In the present study, we report a facile synthesis of polyaniline (PANI) thin films and its application for the sensitive and selective detection of ammonia (NH₃) gas. The branched nanofibers of PANI have been synthesized by in situ oxidative polymerization of aniline monomer with varying oxidant concentration followed by deposition of thin films on a glass substrate by a dip coating method. The deposited thin films were characterized for their structural, morphological, and compositional studies using X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM) and Fourier transform Raman spectroscopic (FT-Raman) techniques. The XRD patterns revealed that the synthesized films are semicrystalline in nature. FE-SEM images exhibit interconnected branched nanofibrous network of PANI. The average fiber diameter observed from FE-SEM images is ~ 45 nm. The gas sensing performance of PANI thin films was studied in terms of sensitivity, response-recovery time and selectivity for different concentration of NH₃ gas. It is observed that PANI thin film gas sensor shown selective response towards NH₃ gas even at a lowest concentration up to 10 ppm at room temperature. Thus, the developed PANI thin film sensor exhibited an admirable gas sensing performances at room temperature towards NH₃ with high sensitivity of 63.50% for 100 ppm of NH₃ gas.