Effect of competitive doping on sensing properties of polypyrrole

Abstract

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 NO _x 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 NO _x 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 .