Effect of competitive doping on sensing properties of polypyrrole

The sensing properties of a conducting polymer, polypyrrole (PP), are modified by competitive doping with tetrafluoroborate or perchlorate and tetrasulfonated metallophthalocyanines (MPcTS, M = Ni or Cu). The Kelvin probe responses of these polymers to dimethylmethylphosphonate, tetrachloroethene and NOx are compared with Kelvin probe signals of commonly prepared polypyrrole, doped with only one anion such as tetrafluoroborate, perchlorate, toluene-p-sulfonate, NiPcTS and CuPcTS. Improved sensing properties were achieved due to competitive doping with the above mentioned anions, compared to commonly prepared PP. The detection range for NOx is 0.4-40 ppm in ambient air and 2-40 ppm in ambient air for dimethylmethylphosphonate. The sensitivity to both substances lies in the range of 67-83 mV (ppm decade)(-1).