A mixed-potential-type NO2 sensor based on a layered-structure Bi2W2O9 sensing electrode

Layered-structure Bi2W2O9 powders synthesized by conventional solid-state reaction and treated by ball milling have been used to create an electrode for a mixed-potential-type NO2 sensor with yttria-stabilized zirconia as an oxygen ion conductor. This sensor was found to provide good sensitivity to NO2 at 500 A degrees C, thanks to the grain refinement induced by ball milling. The electromotive force generated was linear to the logarithm of NO2 concentration in the range of 30-500 ppm, with analysis of the impedance spectroscopy revealing a similar linear correlation between the conductance of the electrode and the logarithm of NO2 concentration. The influence of CO2 was also examined and found to have little effect on the sensitivity of the sensor.