Highly sensitive mixed-potential-type NO2 sensor using porous double-layer YSZ substrate

In this article, the NO 2 sensing performance of the mixed-potential-type yttria stabilized zirconia (YSZ)-based sensor was improved by modifying the three-phase boundary (TPB). The double-tape casting and the pore-forming method were simultaneously used to obtain the porous YSZ-substrate. Furthermore, a group of tape-casting slurries with different starch concentrations (0   wt%, 5   wt%, 10   wt% and 15   wt%) were applied to form the different contact areas of the three-phase boundary (TPB). The scanning electron microscope (SEM) images showed that YSZ-substrate prepared by using the slurry with 15   wt% starch had the largest contact area. The sensor based on the YSZ-substrate with the largest contact areas and the MnCr 2 O 4 sensing electrode (SE) showed the largest response compared with the other sensors when they were exposed to 10–500   ppm NO 2 at 800   °C. The measured polarization ( I – V ) curves indicated that the present sensors operated under the mixed-potential mechanism. In addition, the sensor showed a good selectivity and repeatability to NO 2 .