Preparation and characterizations of polyaniline films for gas sensor application

Abstract

Controlling the emission of toxic gases such as nitrogen dioxide (NO₂), sulfur dioxide (SO₂), hydrogen sulfide (H₂S), carbon monoxide (CO) and methane (CH₄) in the environment requires a new gas sensor that has high sensitivity, selectivity and low cost. Polyaniline is a conductive polymer that is of interest in gas sensor applications due to its reversible behavior with good chemical and air stability. In this work, polyaniline was synthesized by the oxidative coupling polymerization. Protonation doping was used to increase the electrical conductivity and the sensitivity of polyaniline film to toxic gases. Fourier Transform Infrared spectroscopy (FTIR), UV-visible spectroscopy, Thermogravimetric Analyzer (TGA), and Scanning Electron Microscope (SEM) were used to investigate the change in molecular structure, morphology and thermal stability in terms of acid concentration. Four Pint Probe techniques were used to measure the electrical conductivity of polyaniline films under nitrogen and the mixtures of nitrogen and sulfur dioxide atmosphere.