Investigation On Mix-potential NO₂　Sensor Based On Solid Electrolyte

Rapid economic development leads to environmental pollution problems. It has veryimportant significance to develope a sensor capable of detecting the concentration ofNOx.The porous CGO layer on the surface of dense CGO pellets was prepared by screenprinting technique and then sintered at high temperature to sinter the bilayer electrolyte (adense layer and a porous layer). Porous layer is prepared by adding various amounts ofgraphite into the CGO slurries to form different contact areas of the TPB. Thecomposition and microstructure of materials are characterized by XRD and SEM,respectively. The CGO bilayer electrolytes were investigated by AC impedancespectroscopy and the one prepared by adding30wt.%graphite shows the lowest interfaceimpedance. The preparation of porous electrolyte decreases the electrode area specifcresistance obviously as compared to the single dense layer and it is beneficial for theenhancement of electrochemical performance of the gas sensor.A mixed-potential-type NO2sensor using CuO sensing electrode with CGO bilayerelectrolyte was fabricated. This experience study the laws of porous electrolyte withdifferent porosity. The sensor showed good sensitivity to NO2at600~700℃. Theresponse current was linearly related to the concentration of NO2. The sensor showedgood response–recovery characteristics, reproducibility and stability. Negligible effectsof O2and CO2on the sensor response were observed.A mixed potential NO2sensor is fabricated by using an impregnated electrodesensing electrode-nano-structured CuO and the oxygen ion conductor CGO, YBO, YSZ.The composition and microstructure of the sensors were characterized by XRD, SEM andEDS. The sensing performances and mechanisms were investigated by impedancespectroscopy and the impregnated electrode sensing electrode greatly improve theelectrical conductivity of the sensor, demonstrating that more oxygen ion conductorincreases the three-phase-boundry sits and improves the sensitive of sensor. YBO (Bi2O3,8mol%) is a kind of very good oxygen ion conductor. The sensor with CuO-YBOelectrode exhibits well selectivity and rapid response–recovery characteristics to NO2.A mixed potential NO2sensor is fabricated by using a nano-structured perovskite-type oxide LaMn0.8Fe0.2O3sensing electrode prepared in the porous YSZ、 CGO、LSAIO. The YSZ-LMF-sensor shows good anti-interference performance in theinterference test at500℃. A long time text did not affect the response and recovery rate.