Morphological Changes at the Interface of the Nickel‐Yttria Stabilized Zirconia Point Electrode
Morphological Changes at the Interface of the Nickel‐Yttria Stabilized Zirconia Point Electrode
复制标题
镍钇稳定氧化锆点电极界面的形态变化
DOI：
10.1149/1.1838628
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发表时间：
1998
影响因子：
3.9
通讯作者：
R. O̸degaård
中科院分区：
文献类型：
--
作者：
R. J. Aaberg;R. Tunold;M. Mogensen;R. W. Berg;R. O̸degaård
用长时程电位阶跃法和交流阻抗法研究了H2-H2O，Ni/YSZ点电极在1273 K下的电化学行为。通过电子显微镜、能量色散X射线分析和非原位拉曼光谱对电极界面的形态和结构变化进行了评价。阳极电流在电极上产生自催化效应，稳态电流在40 h左右增加到初始值的2倍以上。相反，阴极极化降低了电极的性能，阴极电流显著降低，时间常数约为20 h。材料在反应区中的再分布被建议控制电极活性的大部分变化。在阳极过电位下，观察到Ni被运输到电解质表面，在电极/电解质接触周围形成Ni颗粒的项链。据信这会增加三相边界（TPB）长度并导致电极活性更高。在阴极过电位下，发现Ni向YSZ的转移受到限制，并且提出分散的金属颗粒的团聚减少了TPB长度，从而减少了阴极电流。除了形态学的修改，催化性能的表面显着改变电极极化。当样品在工作条件下保持很长一段时间（135天）时，在电解质的表面上观察到由于材料的偏析而从立方YSZ转变为四方YSZ。没有发现电流的通过在YSZ中产生任何永久相变。
The H 2 -H 2 O, Ni/YSZ point electrode has been investigated using long-term potential step measurements and impedance spectroscopy at 1273 K. Morphological and structural changes at the electrode interface were evaluated by electron microscopy, energy dispersive X-ray analysis, and Raman spectroscopy ex situ. The anodic current was found to induce a self-catalytic effect on the electrode, an the anodic steady state current increased to more than twice the initial value with a time constant of about 40 h. In contrast, cathodic polarization reduced the performance of the electrode, and the cathodic current decreased significantly with a time constant of about 20 h. Redistribution of material in the reaction zone is suggested to control most of the changes in electrode activity. At anodic overpotentials it was observed that Ni was transported to the electrolyte surface, forming a necklace of Ni particles around the electrode/electrolyte contact. This is believed to increase the three-phase boundary (TPB) length and account for the higher activity of the electrode. At cathodic overpotentials the transfer of Ni to the YSZ was found to be restricted, and it is proposed that agglomeration of dispersed metal particles reduced the TPB length, and accordingly the cathodic current. In addition to the morphological modifications, the catalytic properties of the surfaces were significantly altered as the electrode was polarized. Transformation from cubic to tetragonal YSZ, due to segregation of the material, was observed on the surface of the electrolyte when the sample was kept at working conditions for long periods of time (135 days). The passage of current was not found to generate any permanent phase transformation in the YSZ.