Studies on DC conductivity and LPG sensing behaviour of nanostructured polypyrrole-CeO_2 composites

摘要

Sensing of Liquefied Petroleum Gas (LPG) using Polypyrrole-Cerium Oxide (PPy-CeO_2) has been studied in the present work. The conducting PPy-CeO_2 composites were synthesized by in situ deposition technique by placing different weight percentages of PPy-CeO_2 powder (10, 20, 30, 40 and 50%) during the polymerisation of pyrrole. The PPy-CeO_2 composites were later characterised by Fourier Transform Infrared spectroscopy (FTIR), X-ray diffractrometry (XRD) and Scanning Electron Microscopy (SEM). FTIR studies confirm the presence of CeO_2 in the Polypyrrole matrix. XRD patterns reveal some degree of crystallinity in the composite. Further, the study also confirms the formation of nanoparticles in the range 12.08 nm to 15.6 nm. The SEM studies exhibit an aggregated granular morphology of the synthesized composite. The DC conductivity was studied in the temperature range 45-160°C. It was observed that the conductivity remains nearly constant up to 100°C and increases exponentially thereafter. Such behaviour is the characteristic of amorphous materials. Maximum conductivity was observed in 30 wt% of CeO_2 in PPy. On exposure of all the composites to LPG, increase in resistance was observed with the increase in gas concentration. Maximum sensitivity for gas sensing was observed in the composite of 40 wt% of CeO_2 in PPy.