Investigation On Preparation And Properties Of NH₃ Sensors Based On New Sensing Materials

The mixed-potential type NH₃sensor based on yttria stabilized-zirconia（YSZ）shows good thermochemical stability and is used in NH₃detection.The sensing electrode is the key to prepare high-performance sensors,and the heterojunction between composite sensitive electrode materials can improve the sensing performance of the sensor.Zn₂SnO₄is chemically stable at high temperature,and has been used in many fields such as lithium-ion batteries,photocatalysis,and gas sensors,and exhibits high sensing performance.It is a potential NH₃sensor electrode material.Zn₂SnO₄was prepared by solid state method and used as the sensing electrode for the mixed-potential type NH₃sensor based on YSZ.The sensor sintered at 1100°C has the highest sensitivity（-61.2 m V/decade）.There is a liner dependence of the response values of the sensor on the logarithm of NH₃concentrations（25～300 ppm）at 600～650°C.Meanwhile,the sensor exhibits good reproducibility,stability,and low cross-sensitivity to CH₄,CO₂and H₂,but high cross-sensitivity to NO and NO₂of 20.4%and 46.3%.After using a reference electrode of Cu O instead of Pt,the cross-sensitivity to NO and NO₂decreased to 8.8%and 18.4%,but the sensitivity decreases to-32.6 m V/decade.The dual phase composites of Zn₂SnO₄/SnO₂were synthesized by solid state method,and a mixed-potential type NH₃sensor based on YSZ was prepared.When the molar ratio of Zn₂SnO₄to SnO₂is 4:1,the sensor has the highest sensitivity（-73.7 m V/decade）.The Zn₂SnO₄/SnO₂sensing electrode has higher adsorption and electrocatalytic activity,and the cross-sensitivity to NO and NO₂decreases to 8.1%and 21.6%,respectively.The dual phase composites of Zn₂SnO₄/Zn O were synthesized using solid state method for sensing electrode materials of YSZ based NH₃sensor.When the molar ratio of Zn₂SnO₄to Zn O is 2:1,the sensor has the highest sensitivity（-56.1 m V/decade）.Compared with the sensor based on Zn₂SnO₄,the sensor can work normally at 500°C,and the cross-sensitivity to NO and NO₂is reduced to 8.4%and 15.0%,respectively.Figure 55;Table 5;Reference 81...