High-temperature NO2 gas sensor based on stabilized zirconia and CoTa2O6 sensing electrode

- The YSZ-based mixed-potential type gas sensor using CoTa2O6-SE was developed for NO2 detection at high temperature.
- The device utilizing CoTa2O6-SE sintered at 1000 °C gave the highest response of 93 mV to 100 ppm NO2 at 650 °C.
- The sensitivity of the fabricated sensor to NO2 in the concentration range of 5-500 ppm was 80 mV/decade.
- The fabricated sensor also exhibited good selectivity, stability and slight effect of oxygen and moisture at 650 °C.

A mixed-potential type NO2 sensor based on stabilized-zirconia (YSZ) solid electrolyte and novel trirutile CoTa2O6 sensing electrode (SE) prepared through the sol-gel method was developed at high temperature. The effect of CoTa2O6 sensing electrode material calcinated at different temperatures on NO2 sensing property was mainly investigated and the device attached with CoTa2O6-SE sintered at 1000 °C gave the highest response of 93 mV to 100 ppm NO2 and fast response and recovery times at 650 °C. The response of the sensor utilizing CoTa2O6-SE annealed at 1000 °C displayed segmentally linear relationship to the logarithm of NO2 concentration in the ranges of 0.5-5 ppm and 5-500 ppm, which the sensitivities were 12 and 80 mV/decade, respectively. Meanwhile, the present fabricated device also showed good reproducibility, selectivity, long-term stability and slight effect of oxygen and moisture at 650 °C. Furthermore, the mixed potential sensing mechanism proposed was discussed quantitatively and further verified by polarization curve measurement.