Wiewei Meng,Ling Wang,Yuehua Li,Huizhu Zhou,Zhangxing He,Wei Meng,Lei Dai
CoWO 4 -PdO dual phase composites were successfully prepared by self-demixing of the precursor CoPd x WO 4+x (x = 0, 2%, 5%, 10%) calcined at 800 °C and used as sensing electrodes for mixed-potential type NH 3 sensors based on yttria stabilized-zirconia (YSZ) electrolyte. The materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Field-emission scanning electron microscopy (FESEM), respectively. NH 3 response performance of the sensors to different concentrations of NH 3 (20–300 ppm) was evaluated at 350–500 °C. It was found that the sensors attached with CoWO 4 -PdO sensing electrode are much more sensitive to NH 3 than the CoWO 4 -based sensor. Among them, CoWO 4 -5%PdO based sensor gives the highest sensitivity (−76.8 mV/decade at 400 °C), the response signals (Δ V ) of the sensor vary linearly with the logarithm of the NH 3 concentrations in the range of 50–300 ppm at a given temperature. The sensor also exhibits well reproducibility, stability and long-term stability. Furthermore, compared with CoWO 4 -based sensor, the introduction of PdO in CoWO 4 makes the interference of NO 2 on the sensor significantly reduced from 100% to 50%, which is attributed to the fact that the second phase PdO depresses the adsorption of NO 2 .
Lin Yang,Chunping Wu,Yiran Zhang,Bang Xiao,Anqi Jiao,Ke Li,Ting Chen,Reggie Zhan,He Lin
A mixed potential ammonia sensor using In2O3 sensing electrode was prepared, and its sensing performance was enhanced by adjusting particle size with calcination heating rate as well as the utilization of NiCo2O4 reference electrode. It was found that the sensor with a calcination heating rate of 2 °C min−1 had the best performance, with a sensitivity of −61.27 mV decade−1 at 525 °C, and the TEM results showed that the average particle size was 70.36 nm. Furthermore, the sensor exhibited good stability against oxygen concentration fluctuation. The results also indicated that the mixed potential has a linear relationship with the logarithm of NH3 concentration, suggesting that the ammonia sensors in this study conform to the mixed potential theory. To address the issue that most ammonia sensors are susceptible to NO2 interference, NiCo2O4 was used as reference electrode to replace the Pt reference electrode, which could greatly offset the response of NO2 and improve the sensors selectivity. In summary, the developed In2O3/YSZ/NiCo2O4 sensor exhibited a great potential for NH3 monitoring in SCR systems.
危险品化学品经营许可证（带存储）