Chemiresistor gas sensor based on sulfonated dye-doped modified conducting polypyrrole film for high sensitive detection of 2,4,6-trinitrotoluene in air

Abstract

2,4,6-Trinitrotoluene (TNT) is a widely used nitroaromatic explosive and its detection is important in the public security, environmental protection and human health. We presented a sensitive chemiresistor gas sensor based on modified nanostructured dye-doped polypyrrole (PPy) as anfilm to detection of TNT for the first time. The chemiresistor gas sensors were fabricated via electrosynthesis of PPy on Au interdigital electrodes (Au-IDEs) in the presence of the sulfonated dyes. The films were modified with n-butylamine (nBA), and they could absorb TNT molecules by the formation of the Meisenheimer complex. The role of the sulfonated dyes on the behavior of films was studied. The properties of the polymeric films before and after modification were investigated by scanning electron microscopy, elemental mapping analysisand spectroelectrochemical methods The mechanism of sensing was studied by spectroelectrochemical method and response of modified gas sensor was compared to unmodified sensor. The spectroelectrochemical measurements showed that the potential-dependent of spectra in PPy-Dye films is more than in PPy-ClO4 film after modification. Thus dye molecule can act as versatile compound in the polymer backbone. It was found that modified chemiresistor gas sensor has a high sensitivity and good selectivity to TNT over other related gases and no response without modification. The detection limit and linear dynamic range for determination of TNT was 0.2ppb and 9.7–827.8 ppb, respectively.