2.4. Ammonia sensing properties of PANI
2.4.1. Electrochemical impedance spectroscopy and frequency response analysis
The electrical impedance study was carried out using an AUTOLAB electrochemical analyser (PGSTAT 30) with inbuilt frequency response analysis software. The impedance computed from the corresponding voltage and current values at different frequencies was
resolved into its real and imaginary components and plotted versus each other in a Nyquist plot. From this plot, the individual resistive, capacitative and other individual circuit components, which vary with the amount of NH3 adsorbed, were computed.
2.4.2. Amperometric measurement
The amperometric study was also carried out using an AUTOLAB Electrochemical Analyser (PGSTAT 30) with General Purpose Electrochemical System (GPES) software (Ecochemie, Utrecht, The Netherlands).
Fig. 1. Scanning electron microscopic image of polyaniline nanofibers.
Cyclic voltammetry was carried out over a voltage span of -0.3 V to 0.35 V with a scan rate of 0.05 V/s using 20 ppm NH4OH solution to find the suitable potential. An amperometric study was then performed with the gaseous NH3 exposure from 2.5 to 20 ppm.