Effect of electrode microstructure on the sensitivity and response time of potentiometric NOx sensors based on stabilized-zirconia and La5/3Sr1/3NiO4–YSZ sensing electrode

• La5/3Sr1/3NiO4–YSZ composite powders have been synthesized by a simple method.
• The effect of YSZ addition on the electrode microstructure and performance was investigated.
• The effect of sintering temperature on the electrode microstructure and performance was investigated.

The microstructure of a potentiometric NOx sensor’s electrodes considerably affects the sensor performance. In the present paper, nanometric La5/3Sr1/3NiO4 and different YSZ concentrations (5 wt%, 10 wt% and 20 wt%) composite powders were synthesized with microwave-assisted complex-gel auto-combustion method for fabricating NOx sensor electrodes. The sensor electrodes were sintered at 1000 °C, 1100 °C and 1200 °C respectively to obtain a variety of electrode morphology. The electrode porosity decreased with the increased YSZ addition. The sintering temperatures have effect on the porosity and distribution. All the sensors could produce a steady-state response voltage at the lower temperatures. Sensor fabricated with 10 wt% YSZ additional composites and sintered at 1000 °C exhibited the biggest response to NO at 400 °C.