PANI is an inherently conducting polymer only in the presence
of a donor. With ammonia diffusing into the system, a neutralization
of the acid proton donor can be expected which gives rise to
a change in the inherent conductivity of the polymer. At the same
time there is formation of ammonium chloride which in turn also
significantly affects the amperometric response.
PANI
+
HCl
→
PANIH+ +
Cl−
PANIH+ +
Cl− +
NH3→
PANI
+
NH4Cl
The suitable potential for amperometric study inferred from cyclic
voltammetry was found to be 0.106 V. The amperometric response
is very well linearly correlated in the range, 2.5–20 ppm with
squared correlation coefficient of 0.9944 with the conduction,
increasing with increasing ammonia concentration, as seen in Fig. 7.
The % RSD value for the sensor was 1.89.