An amperometric NO2 gas sensor based on Pt/Nafion (R) Electrode

An amperometric NO2 gas sensor based on Pt/Nafion((R)) electrode has been p repared using an impregnation-reduction chemical plating method and tested over the NO2 concentration range from 0 to 485 ppm. A Nafion((R)) membrane was used as a supporting material and Pt/ Nafion((R)) electrode as an anode maintained at a fixed potential, diffusive regions (or mass transfer contr olled regions) with respect to a reference electrode of preferably 0.95-1.1 0 V. A 45 s response time (t(95)) was attained with a 0-485 ppm step change in NO2 concentration whereas the recovery time (t(95)) was 54 s when the N O2 concentration was stepped from 485 to 0 ppm. The sensitivity for the NO2 (0-100 ppm) gas sensor was 0.16 muA/ppm (52 nA/ppm/cm(2)) at room temperat ure. The NO2 sensor, based on a Pt/Nafion((R)) electrode, showed a long-ter m stability greater than 27 days, suggesting its possible applicability for environmental monitoring. (C) 2001 Elsevier Science B.V. All rights reserv ed.