Advances in environmental pollutants detection using polyaniline and polypyrrole based materials via gas sensing...

Environmental pollution has been drastically increased as a result of the significant growth in global population and industrialization. Therefore, it is utmost urgent to monitor the presence of toxic, hazardous, volatile organic compounds (VOC) and gases. Polyaniline (PANI) is among the promising conducting polymers which was extensively used for the development of sensors for chemical detection and monitoring of toxic gases in the environment. PANI offers several advantages including high electrical conductivity, and environmental stability. Similarly, another conducting polymer is polypyrrole (PPy) which has been used for the determination of hazardous and toxic gases. In addition, various reports suggested that hybrid composites of PANI and PPy with carbon materials or metal oxides exhibit better efficiency for gas sensing compared to the pristine PANI or PPy. This review article compiles the previous reports on the development of PANI and PPy based gas sensors for the monitoring of ammonia (NH₃), carbon monoxide (CO), hydrogen sulfide (H₂S), carbon dioxide (CO₂), nitric oxide (NO), nitrogen dioxide (NO₂), acetone, alcohol, and nitroaromatics. The current challenges for improving selectivity, sensitivity and response time of PANI and PPy based materials have been discussed. Furthermore, future perspectives for PANI and PPy based materials are also discussed for their potential applications in real time monitoring of VOC or toxic gases.