Mixed-potential type NO2 sensor using CuCr2O4-CuO composites

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.