A New Method to Measure Oxygen Surface Exchange Kinetics On Porous Mixed Conducting Oxides With Simple Determination...

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Oxygen exchange reaction (OER) is crucial for mixed conducting oxides used in energy applications.
• Standard techniques for measuring OER rate constants (kchem) lack reliability.
• Accurate kinetic data is essential for optimizing devices like fuel cells, sensors, and catalysts.

Purpose of the Study:

• To develop a novel, reliable technique for measuring the oxygen exchange reaction rate constant (kchem) on porous mixed conducting oxides.
• To address the limitations of existing methods in determining accurate kinetic parameters.
• To provide a robust method applicable to materials used in real-world applications.

Main Methods:

• Adaptation of conductivity relaxation measurements on porous ceramic materials.
• Utilizing image analysis to determine the grain size distribution of the porous oxide.
• Development of a new relaxation model integrating relaxation times over the grain size distribution.
• Fitting relaxation transients with kchem as the sole fitting parameter.

Main Results:

• The proposed model accurately determines kchem without requiring optimization, leading to highly reproducible results.
• The technique demonstrates applicability across various mixed conducting oxides and microstructures.
• Low residual values were consistently achieved for all tested porous ceramics.
• The derived kinetics are representative of materials used in practical applications.

Conclusions:

• The new conductivity relaxation technique offers a reliable and robust method for measuring oxygen exchange reaction kinetics.
• This approach overcomes the limitations of standard techniques, providing accurate and reproducible kchem values.
• The findings are directly relevant to the development and optimization of electrochemical devices and catalytic systems.