Low-concentration ammonia gas sensing using polyaniline nanofiber thin film grown by rapid polymerization technique

A thin film of polyaniline (PANI) nanofiber was synthesized by a simple and inexpensive rapid chemical polymerization technique on glass substrate at room temperature. The fundamental peaks that appeared in the absorbance, transmittance, and Fourier transform infrared spectroscopy (FTIR) spectra confirmed the formation of polyaniline salt thin film. The surface morphology investigation was done by field emission scanning electron microscopy (FESEM), which showed cylindrical fibers with an average diameter of similar to 59 nm on the entire surface. The XRD pattern of polyaniline nanofiber shows amorphous nature. The gas sensing properties of polyaniline nanofiber thin films were investigated using a Keithley 2400 I-V (+/- 2 V) sourcemeter interfaced with a computer system, in presence of 0.25-2 ppm and 25-250 ppm in the dry ammonia gas at room temperature. Polyaniline nanofibers show a noticeable response for lower gas concentration, i.e., 0.25-2 ppm of ammonia with response time of similar to 63 s and stability of 19 days. The higher detection limit of the polyaniline nanofiberbased sensor was observed to be 100 ppm with a response of 92% for ammonia gas.