Highly sensitive, room temperature gas sensor based on polyaniline-multiwalled carbon nanotubes (PANI/MWCNTs) nanocomposite for trace-level ammonia detection

Herein we report excellent gas sensor properties of Polyaniline functionalized multiwalled carbon nanotubes (PANI/MWCNTs) based nanocomposite for trace level detection of ammonia (NH3) gas. PANI/MWCNTs nanocomposite was synthesized by in-situ chemical oxidative polymerization of aniline monomer with carboxylated multiwalled carbon nanotubes (C-MWCNTs). The material was structurally characterized by UV–vis Spectroscopy, FT-IR Spectroscopy, Raman Spectroscopy, X-ray Photoelectron Spectroscopy (XPS) and High Resolution Transmission Electron Microscopy (HRTEM). Uniform PANI layer with ∼7 nm thickness was formed on the external walls of the MWCNTs. The gas sensor properties of C-MWCNT and PANI/MWCNTs nanocomposite towards NH3 gas exposure at trace level concentrations (2–10 ppm) under ambient conditions were analyzed and their performances were compared. PANI/MWCNT nanocomposite based sensor exhibited excellent enhancement in sensor response and response/recovery characteristics with good reproducibility towards NH3 gas in comparison with C-MWCNT. The response and recovery time of the PANI/MWCNTs nanocomposite based sensor were found to be significantly improved in the order of a few seconds (6 s) towards NH3 gas. The results reveal the potential application of this sensor in monitoring trace level NH3 gas for varied applications.