The electrochemical property of the galvanic cell, P(O2)I+P(CO), Au/YSZ/Pt, P(O2)II, has been studied for the applications of CO sensor. In order to elucidate the CO-sensing mechanism on Au/YSZ interface, steady state polarization measurements were carried out at 873-1073 K in O2-Ar, CO-CO2, CO-O2-Ar systems. The quantitative analysis of the I-V characteristics revealed the kinetics of the electrode reaction with O2, CO and CO2. The current density at Au/YSZ interface in CO-O2-Ar system can be formulated. As a result, it was confirmed that mixed potential was generated by a small amount of CO in oxygen-containing streams.
