Facile Synthesis of Nanofibrous Polyaniline Thin Films for Ammonia Gas Detection

Abstract

Polyaniline (PANI) nanofibers have been synthesized by in-&!blank;situ chemical oxidative polymerization of aniline monomer. The synthesized nanofibrous PANI was deposited as a thin film on a glass substrate by using dip-coating technique. The deposited thin films of PANI were characterized for their structural, morphological, and compositional studies using x-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), and x-ray photoelectron spectroscopy (XPS). The XRD patterns reveal the amorphous nature of deposited PANI thin films. FE-SEM micrographs exhibited the interconnected nanofibrous network of the PANI. TEM micrographs show the detailed structure of nanofibrous PANI having an average diameter of 45 nm and the selected-area electron diffraction (SAED) pattern reveals the amorphous nature. The prepared PANI thin films were investigated for ammonia (NH3) gas sensing performance. The possibility of PANI thin films being used as sensors was verified in terms of sensitivity, response-recovery time, selectivity, and stability by varying the NH3 gas concentration. The optimized PANI thin-film gas sensor showed a highest sensitivity of 29.30% at room temperature with stable response even after 45 days with 87% retention of stability. The gas-sensing results suggested the PANI nanofibrous sensor possess an excellent response for NH3 gas even at low concentrations of 10 ppm.