Blackening in Zirconia-Based Electrochemical Oxygen Sensor at High Pumping Potentials

By varying the control voltages of commercially available zirconia-based automotive exhaust gas oxygen sensors, other oxygen-containing molecules such as H2O and CO2 can be measured. The measurement method involves increasing the potential across the pumping cell to dissociate oxygen-containing molecules to create free oxygen. At these elevated potentials, oxygen can be removed from the zirconia lattice resulting in blackening of the ceramic resulting in sensor degradation. Techniques to detect early onset of blackening, along with methods for protecting against blackening, are considered.