Fabrication and performance of polypyrrole (Ppy)/TiO2 heterojunction for room temperature operated LPG sensor

In this paper, we report on the fabrication and performance of room temperature operated liquefied petroleum gas (LPG) sensor based on polypyrrole/TiO2 (Ppy/TiO2) heterojunction. Ppy/TiO2 heterojunction was prepared by sequencial depositing TiO2 film by chemical bath deposition and Ppy film by electrodeposition method. Ppy and TiO2 films were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), FTIR and thermo-emf techniques. The XRD study revealed amorphous and nanocrystalline natures for Ppy and TiO2 films, respectively. The SEMs of Ppy and TiO2 films showed cauliflower-like and densely compact morphologies respectively. Maximum gas response of 55% was observed for Ppy/TiO2 heterojunction at 1040 ppm of LPG. Relative humidity affected the gas sensing performance of heterojunction. Good stability, fast response and recovery times indicate that Ppy/TiO2 heterojunction is a one of the candidate for room temperature LPG detection.