Carbon dioxide and water incorporation mechanisms in SrFeO3-δ phases: a computational study.
Carbon dioxide and water incorporation mechanisms in SrFeO3-δ phases: a computational study.
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SrFeO3-δ 相中二氧化碳和水的结合机制：计算研究。
DOI：
10.1039/d0cp03537h
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Pooja Goddard
中科院分区：
文献类型：
--
作者：
leon ford;Peter R. Slater;J. K. Christie;Pooja Goddard
随着低温合成路线的更高倾向沿着向更低的固体氧化物燃料电池操作温度的移动，锶铁氧体中的水和二氧化碳结合是重要的。尽管如此，其机制尚不清楚。在这项工作中，基于经典势的计算技术被用来确定SrFeO 3-δ和SrFeO 2.5中的水和CO2掺入机制的有利性。我们的研究表明，本征弗伦克尔和肖特基型缺陷是不太可能形成的，但水和二氧化碳的掺入是有利的，在这两个阶段。水的掺入是可能的立方相和brownmillerite相，与氢氧根离子更喜欢坐在八面体氧网站在这两种结构，导致轻微倾斜的共享八面体。间隙氢氧根离子只可能用于brownmillerite相，其中氢氧根离子在相邻的FeO 4四面体链之间最稳定。当碳酸盐分子存在于铁位点上时，通过碳酸盐缺陷的二氧化碳掺入是最有利的，优选具有较低氧配位的铁位点。这涉及在铁位点周围形成多个氧空位，因此我们得出结论，碳酸盐可以捕获氧空位。
With a higher propensity for low temperature synthesis routes along with a move toward lower solid oxide fuel cell operating temperatures, water and carbon dioxide incorporation in strontium ferrite is of importance. Despite this, the mechanisms are not well understood. In this work, classical-potential-based computational techniques are used to determine the favourability of water and CO2 incorporation mechanisms in both SrFeO3-δ and SrFeO2.5. Our studies suggest that intrinsic Frenkel and Schottky type defects are unlikely to form, but that water and carbon dioxide incorporation are favourable in both phases. Water incorporation is likely for both the cubic and brownmillerite phases, with hydroxyl ions preferring to sit on octahedral oxygen sites in both structures, causing slight tilting of the shared octahedra. Interstitial hydroxyl ions are only likely for the brownmillerite phase, where the hydroxyl ions are most stable between adjacent FeO4 tetrahedral chains. Carbon dioxide incorporation via carbonate defects is most favourable when a carbonate molecule exists on an iron site, preferring the iron site with lower oxygen coordination. This involves formation of multiple oxygen vacancies surrounding the iron site, and thus we conclude that carbonate can trap oxygen vacancies.
影响因子：
4
作者：
C. Hancock;J. M. Porras-Vázquez;P. Keenan;P. Slater
通讯作者：
C. Hancock;J. M. Porras-Vázquez;P. Keenan;P. Slater