Kinetics of competing exchange of oxygen and water at the surface of functional oxides
| Autor: | Mathew Niania, Vincent Thoréton, John A. Kilner |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Work (thermodynamics)
Kinetics Oxygen transport Analytical chemistry Oxide General Physics and Astronomy chemistry.chemical_element 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Oxygen 0104 chemical sciences chemistry.chemical_compound chemistry TRACER Crystallite Physical and Theoretical Chemistry 0210 nano-technology Water vapor |
| Zdroj: | Physical Chemistry Chemical Physics. 23:2805-2811 |
| ISSN: | 1463-9084 1463-9076 |
| DOI: | 10.1039/d0cp04953k |
| Popis: | The presence of water vapour in the input gas stream influences the performance of air electrodes of solid oxide cells. In this work, the oxygen transport kinetics were determined by isotopic exchange depth profiling at 350 °C on polycrystalline La0.6Sr0.4Co0.2Fe0.8O3-δ samples in humidified oxygen, comparing the differences in tracer diffusion profile using either 18O2 or H218O as the labelling medium. The apparent surface exchange coefficients of oxygen were determined in each case and used together to estimate the oxygen surface exchange coefficients of molecular oxygen and water. It was found that, in humid conditions, the surface exchange coefficient of molecular oxygen is significantly decreased in comparison to a reference in dry conditions. In addition, the surface exchange coefficient of water is higher than that for molecular oxygen. This is in good agreement with the hypothesis that, water monopolises the active exchange sites at the material surface and thus oxygen from water exchanges faster than the one of molecular oxygen. |
| Databáze: | OpenAIRE |
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