Structural evolution, electrochemical kinetic properties, and stability of A-site doped perovskite Sr1−xYbxCoO3−δ
| Autor: | Xingjian Xue, Myongjin Lee, Chunyang Yang, Kyle S. Brinkman, Chunlei Ren, Yun Gan, Robert D. Green |
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| Rok vydání: | 2020 |
| Předmět: |
Materials science
Renewable Energy Sustainability and the Environment Ionic bonding chemistry.chemical_element 02 engineering and technology General Chemistry Crystal structure Atmospheric temperature range 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Oxygen 0104 chemical sciences Tetragonal crystal system Chemical engineering chemistry Vacancy defect General Materials Science Thermal stability 0210 nano-technology Polarization (electrochemistry) |
| Zdroj: | Journal of Materials Chemistry A. 8:10450-10461 |
| ISSN: | 2050-7496 2050-7488 |
| DOI: | 10.1039/d0ta03476b |
| Popis: | Mixed ionic and electronic conducting (MIEC) perovskite SrCoO3−δ is a widely studied (electro)catalyst for the oxygen reduction reaction (ORR) and possesses different crystal structures at different temperatures. These temperature dependent phase transitions significantly impact the ordering of oxygen vacancies and electrochemical kinetic properties as well as the reliability of the related devices. Some of the crystal structures formed, e.g. hexagonal phases, turn out to be almost impermeable to oxygen gas. Therefore, it is important to stabilize the crystal structure of SrCoO3−δ that favors the ORR over a wide temperature range. Herein, the partial substitution of the A-site Sr with Yb is systematically studied, including synthesis, characterization and analysis of structural evolution, electrochemical kinetic properties, thermal stability, and stability in a CO2-containing atmosphere. The results indicate that Sr0.90Yb0.10CoO3−δ is able to stabilize the tetragonal crystal structure with less ordered oxygen vacancies, leading to polarization resistances of 0.051, 0.115 and 0.272 Ω cm2 at 750, 700 and 650 °C, respectively, on symmetrical cells. Sr0.90Yb0.10CoO3−δ demonstrates a very stable surface oxygen vacancy distribution and electronic structure near oxygen vacancies but dissociation of adsorbed oxygen molecules into atomic oxygen is affected by surface Sr segregation, and polarization resistance degradation is mainly induced by surface Sr segregation. Furthermore, Sr0.90Yb0.10CoO3−δ exhibits excellent thermal stability as well as excellent recovery stability and improved polarization performance after a few pure air/CO2-containing air treatment cycles at 700 °C. However, a hysteresis behavior of polarization performance is observed at 650 °C during gas cycling treatment, which may cause long-term degradation of the Sr0.90Yb0.10CoO3−δ electrode. The different polarization behaviors during gas cycling treatment are induced by different sensitivities of the formed surface strontium carbonate and chemisorbed surface oxo-carbonaceous species to different operating temperatures. |
| Databáze: | OpenAIRE |
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