An amperometric NO2 gas sensor based on Pt/Nafion® Electrode

An amperometric NO2 gas sensor based on Pt/Nafion® electrode has been prepared using an impregnation–reduction chemical plating method and tested over the NO2 concentration range from 0 to 485 ppm. A Nafion® membrane was used as a supporting material and Pt/Nafion® electrode as an anode maintained at a fixed potential, diffusive regions (or mass transfer controlled regions) with respect to a reference electrode of preferably 0.95–1.10 V. A 45 s response time (t95) was attained with a 0–485 ppm step change in NO2 concentration whereas the recovery time (t95) was 54 s when the NO2 concentration was stepped from 485 to 0 ppm. The sensitivity for the NO2 (0–100 ppm) gas sensor was 0.16 μA/ppm (52 nA/ppm/cm2) at room temperature. The NO2 sensor, based on a Pt/Nafion® electrode, showed a long-term stability greater than 27 days, suggesting its possible applicability for environmental monitoring.