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Abstract: The mixed-potential NOx sensor based on yttria-stabilized zirconia (YSZ) and oxide electrode is considered as a potential device used for the on-board diagnostics. Over the past decades, many researchers have paid their attentions on such YSZ based potentiometric NOx sensors and gotten a lot of achievement in developing new type electrode materials. Recently, in order to enhance the sensing performance of the mixed potential type NOx sensor, we have been focusing on modifying the triple-phase-boundary (TPB) by various techniques, including chemical corroding, the double-tape casting, the pore-forming and laser fabrication method. We also designed and prepared the microstructure of the oxide electrodes by controlling the sintering process for increasing the sensitivity of the NOx sensor. This paper reviews our works with regard to the above-mentioned two aspects. [Copyright &y& Elsevier]

Abstract: A series of tungstate MWO4 (M=Co, Zn and Ni) has been prepared by the polymeric precursor method. Meanwhile, yttria stabilized-zirconia (YSZ) based sensors using these oxides as sensing electrodes were investigated, and among the oxides tested, CoWO4 was found to be the most suitable for the sensing electrode (SE) of the ammonia sensor. The sensor attached with CoWO4 shows the fast response and recovery characteristics (not more than 5s respectively) and large sensitivity (−51mV/decade) at elevated temperature. The electric potential difference (∆V) of the sensor varies almost linearly with the NH3 concentrations in the examined range of 50–1000ppm. The SEM observation reveals that the special microstructure of CoWO4-SE, bulky rod-like crystals coated by tiny particles, plays a significant role in sensing performance. [Copyright &y& Elsevier]