A compact, solid-state, amperometric NO2 sensor was fabricated using a small Na+ conductor (NASICON) plate and an NaNO2 layer deposited on the counter electrode. With the sensing electrode polarized at a constant potential relative to the reference Au electrode coated with an inorganic adhesive, electric current flowing through the device under exposure to NO2 was measured as a sensing signal. The current response was almost linear with NO2 concentration in the range 10 ppb-1 ppm at 150°C. The 90% response time to even 20 ppb NO2 was ca. 60 s. The NO2 sensitivity was hardly affected by the coexistence of CO2, H2O and O2. Furthermore, the device could be operated rather stably during the test period of ca. 30 days except for several days in the early stage. A sensing mechanism is proposed on the basis of the sensing characteristics obtained.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry