Room-temperature fabrication and characterisation of ammonia gas sensors based on FeCl3-doped polypyrrole thin films

Abstract

The FeCl3-doped conductive polymer (PPy) films exhibited nanoparticle clusters and nanosheet structures that were grown directly on the surface of the Pt/Al₂O₃ electrodes in a simple way using a combination of spray coating and vapour phase polymerisation. The morphological and structural characteristics of PPy film are analysed through scanning electron microscopy (SEM) images, energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared (FTIR) spectroscopy. The results of the gas sensitivity measurement show that all PPy films respond well to
NH₃ gas at room temperature and the highest response of 135% was found when the PPy@30 sample was exposed to 400 ppm NH₃ gas. The fabricated PPy sensors not only exhibit fast response/recovery times, especially with response times of only a few seconds, but also show excellent selectivity toward NH₃ gas at room temperature. The obtained results demonstrate that the performance of NH₃ gas sensors at room temperature is significantly affected by the doping and surface morphology of the PPy films. Additionally, the gas sensing mechanism of the sensor based on PPy films has also been discussed in this study.