Journal article
Limitations of potentiometric oxygen sensors operating at low oxygen levels
Physical Chemistry, Department of Chemistry, Technical University of Denmark1
Department of Chemistry, Technical University of Denmark2
Microstructures and Interfaces, Fuel Cells and Solid State Chemistry Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark3
Fuel Cells and Solid State Chemistry Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark4
Risø National Laboratory for Sustainable Energy, Technical University of Denmark5
Electrochemistry, Fuel Cells and Solid State Chemistry Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark6
The electrochemical processes that limit the range of oxygen partial pressures in which potentiometric oxygen sensors can be used, were analysed using a theoretical and an experimental approach. Electrochemical impedance spectroscopy was performed on porous Pt/yttria stabilised zirconia (YSZ) electrodes between 10−6 and 0.2 bar and at temperatures between 500 and 950 °C.
The flow of oxide ions and electron holes through a sensor cell, with a YSZ electrolyte, were calculated under similar conditions. The oxygen permeation of the sensor cell was insignificant at an oxygen partial pressure of 10−6 bar for an inlet flow rate higher than 2 L h−1 between 600 and 800 °C. The polarisation resistance measured between 10−6 and 10−4 bar was found to be inversely proportional to the oxygen partial pressure, nearly temperature independent and inversely proportional to the inlet gas flow rate, which shows that gas phase mass transport processes were dominating.
The time constant of the gas phase mass transport processes was found to be inversely proportional to the oxygen partial pressure. The response time of these processes therefore limits the oxygen partial pressure range in which potentiometric oxygen sensors can be used.
Language: | English |
---|---|
Year: | 2011 |
Pages: | 1159-1167 |
ISSN: | 18733077 and 09254005 |
Types: | Journal article |
DOI: | 10.1016/j.snb.2011.09.041 |
ORCIDs: | Hansen, Karin Vels and Mogensen, Mogens Bjerg |