Chemiresistive ammonia gas sensor based on branched nanofibrous polyaniline thin films

Abstract

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.