Detection of NO by pulsed polarization of Pt I YSZ

Pulsed polarization is a measurement technique based on alternating voltage pulses with intermediate pauses for self discharging. The possibility of NO detection by this dynamic measurement technique using conventional lambda sensors is shown in prior investigations. The discharging after polarization depends strongly on NO content in the low ppm range. Due to faster discharging at NO containing atmosphere compared to base gas, the voltage difference between the discharge curves can act as a characteristic value; this voltage change shows a logarithm dependency on NO concentration. The feasibility of NO sensing by use of a planar, more cost-effective sensor (Pt electrodes on yttria stabilized zirconia) is evaluated in detail. The optimum range for NO detection is found at 400 °C by comparing the NO sensitivities at temperatures from 300 °C up to 550 °C.