CuCr2O4-CuO复合敏感电极混合位型NO2传感器的研究

Mixed-potential type NO2 sensor using CuCr2O4-CuO composites

摘要:

采用Y₂O₃稳定的La₁₀Si₆O₂₇为固体电解质,构建致密层/多孔层结构,在多孔层上采用丝网印刷技术以尖晶石结构CuCr₂O₄-CuO为复合敏感材料,制备了混合位型NO₂传感器。采用XRD、SEM对 NO₂传感器敏感材料的相组成和微观形貌进行了表征,应用电化学工作站测试了传感器的敏感性能和响应机理。结果表明：粒径200~300nm的CuCr₂O₄-CuO均匀分布在约20μm厚的多孔层中；极化曲线和交流阻抗结果表明该传感器为混合位型,在600~700℃、NO₂浓度25~300ppm,传感器响应信号值与NO₂浓度之间呈良好线性关系,600℃时具有较好的敏感性、重现性和稳定性；共存的NH₃、CH₄、H₂及CO₂对传感器敏感性能几乎没有影响,O₂在5~21%浓度范围内随浓度的增大电位值呈一定的线性减小,实际应用中可以通过O₂传感器进行校正。

Abstract:

A novel amperometric-type NO2 sensor based on 6 wt%Y2O3- La10Si6O27 (LSO) and CuCr2O4-CuO composites sensing electrode was fabricated. CuCr2O4-CuO composites were prepared by ammonium hydrocarbonate precipitation method. And then these particles were dispersed in LSO porous layer by Screen printing method to preparation the sensor. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to characterize the phase composition and morphology of the samples. The phase composition of CuCr2O4-CuO composites characterized by XRD were CuCr2O4 and CuO, and the morphology characterized by SEM were irregular sheets with 200-300 nm. These particles is evenly distributed in the porous layer with a thickness of about 20 μm. The polarization curves and the AC impedance results showed that the sensor is a mixed-potential type. The sensor exhibited well response-recovery characteristics to NO2. The response signal was almost linear to NO2 concentration in the range between 25 ppm and 300 ppm at 600- 700 °C. The sensitivity increased and reached 19.3 mV/dec. at 600°C. The response potential of the sensor is slightly affected by co-existant NH3, CH4, H2 and CO2. However, within the concentration range of 5-21%, the potential value of the sensor decreases linearly with the increase of oxygen concentration. The actual application can be calibrated with another O2 sensor.