Performance Of The Zirconia-based Hydrocarbons Gas Sensors Comprised Of Nano-based NiO With Different Morphology

The vehicles bring out great convenience for the people life in the transportation. However,the studies have shown that the emissions of NOx、CO、hydrocarbons(HCs) and other pollutants from vehicles become increasingly severe. HCs is the main source of photochemical smog which could greatly endanger human health. Therefore, the research about controlling vehicle emissions become the important work of environmental protection in the city. Due to the simple and fast real-time monitorfor the HCs in exhaust, HCs sensors based on Yttria-Stablilzed Zirconia(YSZ) have gained widespread attentions. Since the significantly effect of morphology of the sensing-electrodes(SEs) on the performance of YSZ based gas sensors, several SEs with different morphology were synthesized in this paper and utilized on the YSZ-based HCs sensors.Additionally, the sensing performance of the gas sensors were evaluated.In this paper, N O sensing electrode(SE) is prepared in seven different morphologies by hydrothermal method and Pt is prepared as reference-electrode(RE), both electrodes were printed on the YSZ electrolyte by using thick film screen printing technique. The sensors’ s sensing properties, stability, catalytic selectivity of Ni O, impedance spectroscopy and polarization curves of the sensor were characteristized. The results show that Ni O sensitive electrodewith different morphologies obtain the best performance at 600 oC. At 600 oC, the sensor with line-like Ni O-SE has the lowest catalytic efficiency to 100 ppm C3H6 in 5 vol.% O2, thus allowing more gas diffuse to three-phase interface. The sensor with line-like Ni O sensitive-electrode has the smallest interface impedance, thus showing the best performance of the sensor response.The potential value calculated with polarization curves agree well with the experimental values.To improve the sensing performance, mixed-potential-type HCs sensor using YSZ mixed Ni O as sensing electrode was fabricated, and the sensing characteristics of sensors were studied. The results indicate that: 20% YSZ mixed Ni O sensitive electrode sensor having the maximum output potential at 600 oC.The manganese-based electrode is stabilityand much inert to oxygen below 600 oC.The experiment was conducted with Mn2O3-RE and Ni O-SEs. The results show that conditions, the step-response and reproducibility of three sensors to 20-500 ppm C3H6 were tested at 550 oC in 5vol.% O2, the sensors have a significant difference between the response value, wherein the line-like Ni O-SE sensor’s response reaches 170 m V to 100 ppm C3H6 at 550 oC.In addition, three kinds of YSZ-based amperometric HCs sensor were fabricated based on Ni O sensitive electrode materials, and the sensor’s sensitivity, stability and selectivity were characteristized. The results show that under the condition of 550 oC, the current response of the sensor has a good linear relationship with the gas concentration, but the sensor long-term stability should be further improved.