NO₂ gas sensing with polyaniline nanofibers synthesized by a facile aqueous/organic interfacial polymerization

A new chemical gas sensor for NO₂ detection is reported using polyaniline nanofibers synthesized by an interfacial polymerization method. Upon exposure to different contents of NO₂ gas, the emeraldine salt form of polyaniline leads to a large increase in resistance-greater than three orders of magnitude in 100 ppm. In these cases, NO₂ acts as a strong oxidant, converting the emeraldine form (half oxidized form) of polyaniline to its higher oxidized state. The structures of the nanofibers (high surface area, porosity and small diameters) enhance diffusion of the molecules and oxidative agent into the nanofibers, resulting into high sensitivity and short response time for NO₂ detection.