Investigation On NO₂ Sensors Based On LSO Electrolyte And Nano-structured Sensing Materials

Continuously increasing industrial progress makes an enormous impact on the atmosphere by emitting hazardous gases.Exhaust gases including NO_x.So precisely monitoring and controlling the NO_x emission become very meaningful.In this paper,the impedancemetric NO₂ sensor was constituted by oxyapatite lanthanum silicate electrolyte and sensing electrodes.The LSO and electrodes were characterized by XRD and SEM measurements and the sensing characteristics of NO₂ sensors were tested.The experimental results are as follows:Alkali elements doped lanthanum oxyapatites La₉.95A₀.05Si₆O₂6.95（A=Li,Na,K）were synthesized by solid state reaction.SEM showed that the increase of sintering temperature helped to electrolyte density.XRD showed that all the La₉.95A₀.05Si₆O_27-δelectrolytes consist of a single hexagonal apatite structure.Through electrochemical impedance spectroscopy analysis can we know Li⁺ and K+ acted as the sintering aid role at low temperatures and high temperatures,respectively.Total conductivity of LASO was well fitted to the Arrhenius equation.Among them,LKSO exhibited the lowest activation energy（0.886 eV）and the highest conductivity of 1.12×10-2 S cm^-1 at 800℃.Co₃V₂O₈ particles was prepared by wet-impregnation technique,then prepared NO₂ sensor.SEM showed that Co₃V₂O₈ particles uniformly distribute in the porous layer.The impedance acted as response signal to analysis the sensitivity at 600 ℃ ⁷50℃.The results showed that at 650℃ with 10 ul impregnation the sensor displayed the largest sensitivity,quicker response transients.The sensor can be used to monitor the total NO_x.LSMC nano particles was prepared by wet-impregnation technique then prepared the double-sided NO₂ sensor.SEM showed that LSMC particles uniformly distribute in the porous layer.The phase angle acted as response signal to analysis the sensitivity of sensor at 600℃⁷50℃.The results showed that the sensor using sensing electrode at650℃ and 0.5 Hz displayed the largest sensitivity,quicker response value and selectivity.