Camphor sulfonic acid doped PPy/α-Fe2O3 hybrid nanocomposites as NO2 sensors

Abstract

PPy/α-Fe₂O₃ hybrid nanocomposites with different weight percentages (10–50%) of CSA were successfully prepared by using a solid state synthesis method. Thin films of prepared hybrid nanocomposites were deposited on glass substrates using a spin coating technique and have been characterized using various techniques such as XRD, FESEM and TEM. The gas sensing performance of 10–50% CSA doped PPy/α-Fe₂O₃ nanocomposite thin films were studied towards NO₂, Cl₂, NH₃, H₂S, CH₃OH and C₂H₅OH gases. Among various compositions, 30% CSA doped thin films were found to be highly sensitive and selective towards NO₂ gas at room temperature i.e. with a chemiresistive response of 64% at 100 ppm with a reasonably fast response time of 148 s. The sensor responses in relation to the CSA doping concentration and the gas concentration have been systematically studied. Additionally, other sensing properties such as reproducibility, cross-sensitivity, sensing linearity and stability were also studied and explored. The CSA doped PPy/α-Fe₂O₃ nanocomposites exhibited better response, stability and shorter recovery times as compared to PPy and PPy/α-Fe₂O₃ nanocomposites alone. Therefore, it is expected that such a material with excellent gas sensing properties at room temperature can be used for high performance selective NO₂ sensors.