Fabrication of a Novel Flexible Room Temperature Hydrogen Sulfide (H2S) Gas Sensor based on Polypyrrole Films

Polypyrrole (PPy) was synthesized by chemical oxidative polymerization technique using Ferric Chloride (FeCl3) as an oxidant and Pyrrole as a monomer. The ratio of oxidant to monomer was 2.51. The polymerization was carried out at ~ 5 C. The materials were characterized by using SEM, FTIR and XRD. The electrical conductivity was measured by two probe method and was found to be 1.389 10-2 S/cm at room temperature. H2S gas sensor was fabricated by casting thin films of Polypyrrole on the integrated electrodes, at room temperature. Sensing experiments were performed on these films with the injection of 10 ppm to 100 ppm level H2S at room temperature. The response and recovery time were obtained. It was found that, response time decreased from 64 sec to 13 sec as the concentration of H2S increased from 10 ppm to 100 ppm, while the recovery time increased from 192 sec to 644 sec. The possible response mechanism is discussed.