Room temperature ammonia gas sensing properties of polyaniline nanofibers

Polyaniline nanofibers (PAni NFs) were synthesized using in-situ chemical oxidative polymerization process, through varying ratios of monomer aniline (AN) and oxidant ammonium persulfate (APS), and utilized for ammonia (NH3) detection. Structure, morphology, and surface composition of as-synthesized PAni NFs was examined through X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning, and transmission electron microscopy. Formation of porous interconnected network of PAni NFs of the diameter of 60-70nm was confirmed through surface morphological analysis. Effect of varying AN/APS ratios on the gas sensing activities of PAni NFs sensors was studied towards various reducing and oxidizing gases thoroughly and discussed. The PAni NFs sensor developed using equal AN/APS ratio demonstrates excellent selectivity towards NH3 (62% response to 100ppm) and capable to detect 1ppm concentration of NH3 at room temperature. The interaction mechanism of the PAni NFs sensor with oxidizing and reducing gases was studied using impedance spectroscopy and discussed.