AMPEROMETRIC SOLID-STATE NO2 SENSOR-BASED ON PLASTICIZED PVC MATRIX CONTAINING A HYDROPHOBIC ELECTROLYTE

An amperometric solid-state sensor for the detection of nitrogen oxide in air has been constructed using a gold minigrid indicator electrode , Pt/air reference and platinum counter electrodes in contact with a s olid polymer electrolyte containing 9.6% PVC, 87.0% 2-nitrophenyl octy l ether and 3.4% tetrabutylammonium hexafluorophosphate. The stationar y electric current corresponding to the NO, reduction at the indicator electrode at -0.3 V versus Pt/air electrode exhibited a linear depend ence on the NO, concentration in the range 0.2 to 5.0 ppm, with a sens itivity of 21.7 nA ppm(-1) (at 54% relative humidity), a standard devi ation of 3.3 nA at 1.06 ppm NO2, and a detection limit of 75 ppb. The time constant or time required to attain 90% of the steady-state respo nse is 3.3 s or 14 s, respectively. The response decreases linearly wi th increasing relative humidity (RH) with a slope of 0.14 nA ppm(-1) p er 1% RH. The sensor shows an excellent stability over one month. (C) 1997 Elsevier Science S.A.