Characteristics of an HC sensor using a Pr6O11 electrode

The characteristics of an HC sensor consisting of a gas-detection cell and an oxygen pump cell have been investigated. A Pt active electrode and a Pr6O11 inactive electrode were formed on YSZ in the gas-detection cell using a sputtering technique, and the concentration of hydrocarbon gases was determined from the electromotive force generated between these two electrodes. The pump cell was assembled such that the oxygen concentration in the gas-detection space was decreased. At 800 °C, the gas-detection cell showed high output sensitivity for hydrocarbon gases such as CH4 and C3H8. However, the sensitivity was low for H2 and CO. The sensor output increased when the pump cell was operated in C3H8/O2/N2. This result shows that decreasing the oxygen concentration in the gas-detection space by using the pump cell is an effective technique for improving the detection sensitivity of the sensor.