Interfacial Charge Transfer and Chemical Bonding in a Ni–LaNbO4 Cermet for Proton-Conducting Solid-Oxide Fuel Cell Anodes
Interfacial Charge Transfer and Chemical Bonding in a Ni–LaNbO4 Cermet for Proton-Conducting Solid-Oxide Fuel Cell Anodes
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DOI：
10.1021/cm302317f
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发表时间：
2012-10
影响因子：
8.6
通讯作者：
D. Kepaptsoglou;K. Hadidi;O. Løvvik;A. Magrasó;T. Norby;A. Gunnæs;A. Olsen;Q. Ramasse
中科院分区：
文献类型：
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作者：
D. Kepaptsoglou;K. Hadidi;O. Løvvik;A. Magrasó;T. Norby;A. Gunnæs;A. Olsen;Q. Ramasse
本文研究了质子传导固体氧化物燃料电池(SOFC)阳极材料Ni-LaNbO4金属陶瓷中Ni与LaNbO4颗粒界面的结构和化学特性。在像差校正的扫描电子显微镜中进行的电子能量损失谱(EELS)显示，在界面处没有反应层或互扩散层。界面EELS精细特征的变化反映了Ni的价态变化和La的电子结构的变化，这些变化与界面上的电荷转移有关。实验结果与基于密度泛函理论的从头计算结果很好地吻合，该理论预言金属和陶瓷之间在这个突变界面处形成直接化学键，从而导致电子电荷在界面上的重新分布。
In this work, we present an atomic scale study of the structural and chemical characteristics of interfaces between Ni and LaNbO4 grains in Ni–LaNbO4 cermets, a model composite material for anodes in proton-conducting solid-oxide fuel cells (SOFC). Electron energy loss spectroscopy (EELS) performed in an aberration-corrected scanning transmission electron microscope reveals the absence of reaction or interdiffusion layers at the interface. Changes in the valence state of Ni as well as in the electronic structure of La, reflected by changes in the EELS fine features at the interface, are shown to be related to charge transfer across the interface. The experimental results are in excellent agreement with ab initio calculations based on density functional theory, which predict that direct chemical bonds are formed between the metal and the ceramic at this abrupt interface, resulting in a redistribution of electronic charge across the interface.