CO determination in air by YSZ-based sensors

Potentiometric solid state gas sensors have been developed for CO monitoring in air. The following galvanic cell was investigated: Pt|M, (CO+O2)|ZrO2-Y2O3|(O2), Pt|Pt where M is either a Pt or an RuO2 layer. Sensors were characterized between 350 and 650 °C with carbon monoxide partial pressures ranging from 1 to 80 Pa. A linear relationship between the electromotive forces (e.m.f.s) and log(p co ) was observed. The e.m.f. versus time curve can be described by: where E(0) and E(∞) are the values at the time at which the pressure of CO is abruptly changed (taken as t=0) and that at which steady-state conditions are reached. τ is a time constant and n is an adimensional exponent. Results obtained with Pt and RuO2 electrode materials are compared and discussed.