Facial Growth of Polyaniline based Sensors for Gas Sensing Application: Langmuir Theoretical Approach

PANI based sensors has been synthesized for methanol detection i.e. pristine PANI and its composites have been synthesized using chemical oxidative polymerization approach with various doping concentration (00, 10, 20 and 40 wt.%) of manganese dioxide. The PANI/MnO ₂ composite with 10wt% of MnO ₂ has porous structure as well as small particles size as compared to PANI shown by FESEM analysis. The greatest interaction across PANI and MnO ₂ nanoparticles lead to the conversion of PANI from the highly oxidized states to oxidized states and is established using Raman investigation. The FESEM and Raman spectroscopy confirms the preparation of PANI and its composites. The sensing response (%), response and recovery time of fabricated sensors towards the methanol environment has been calculated by measuring the change in surface current of samples in different methanol environments with respect to without methanol environment at room temperature. The PANI/MnO ₂ composites show the better response as compared to pristine PANI and response increases with increase in dopant concentration as well as ppm levels of methanol. The maximum response was calculated for PANI/MnO ₂ composite with 40wt% of MnO ₂ which is ~ 48% and better response time 90 seconds at 60ppm of methanol vapors. The better recovery time was observed for PANI at 40ppm level of methanol vapors. The adsorption and desorption of gas molecules under Langmuir kinetic theory for the adsorption and desorption of methanol has also been thoroughly examined, along with any potential theoretical parallels to the mechanism of gas sensing. Using Langmuir adsorption-desorption kinematic fits, theoretical parameters related to the sensing qualities have been assessed from the experimental curves.