In situ prepared composite of polypyrrole and multi-walled carbon nanotubes grafted with sodium polystyrenesulfonate as ammonia gas sensor with wide detection range

Abstract

Abstract NH3 gas sensors with good sensing performance including wide detection range at room temperature are highly desirable for a large variety of applications. In this work, multi-walled carbon nanotubes grafted with sodium polystyrenesulfonate (PSSNa-MWCNTs) are prepared via a controlled radical polymerization and show good dispersibility in water. The composite of polypyrrole with PSSNa-MWCNTs (PPy/PSSNa-MWCNT) is prepared by in situ vapor phase polymerization of pyrrole to fabricate NH3 gas sensors. Effects of the content of PSSNa-MWCNTs, the concentration of the oxidant, polymerization time and temperature on the gas sensing properties of the composite are investigated at room temperature. It is revealed that the composite shows much higher response magnitude than the single components. Under optimal conditions, PPy/PSSNa-MWCNT exhibits very wide detection range from 5 to 2000 ppm, and good sensing linearity over 5–20 ppm and 20–100 ppm, respectively. Moreover, the electrical responses of the composite towards NH3 gas are fast (response and recovery time to 1000 ppm NH3 gas are 16.7 s and 143.6 s, respectively), reproducible and highly selective. The interactions between PPy and MWCNTs promote the charge transfer in the composite, leading to good sensing performance and exhibiting a synergetic effect.