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arXiv 0802.0193cond-mat.mtrl-sci
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氧在LaMnO3(001)表面吸附的第一性原理模拟

First principles modeling of oxygen adsorption on LaMnO3 (001) surface

Eugene A. Kotomin, Yuri A. Mastrikov, Eugene Heifets, Joachim Maier

摘要:

我们提出并讨论了原子和分子氧在固体氧化物燃料电池阴极模型材料LaMnO 3(001)表面的吸附和扩散的从头算DFT平面波超原电池计算结果。从气相中的O2分子的解离吸附是积极有利的表面Mn离子,即使在无缺陷的表面上。吸附的O离子的表面迁移能被发现是相当高的,1.6 eV。我们预测,吸附的O原子可以渗透到电极的第一平面时,更多的移动表面氧空位(迁移能为0.69 eV)的方法,O离子强烈结合到表面Mn离子。从头算热力学预测,在典型的SOFC工作温度(~1200 K)下,吸附有氧原子的MnO 2(001)表面在很宽的氧气压力范围内(高于10^2 atm)是最稳定的。

英文摘要:

We present and discuss the results of ab initio DFT plane-wave supercell calculations of the atomic and molecular oxygen adsorption and diffusion on the LaMnO3 (001) surface which serves as a model material for a cathode of solid oxide fuel cells. The dissociative adsorption of O2 molecules from the gas phase is energetically favorable on surface Mn ions even on a defect-free surface. The surface migration energy for adsorbed O ions is found to be quite high, 1.6 eV. We predict that the adsorbed O atoms could penetrate into electrode first plane when much more mobile surface oxygen vacancies (migration energy of 0.69 eV) approach the O ions strongly bound to the surface Mn ions. Ab initio thermodynamics predicts that at typical SOFC operation temperatures (~1200 K) the MnO2 (001) surface with adsorbed O atoms is the most stable in a very wide range of oxygen gas pressures (above 10^2 atm).

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