New Insight into Hydrogen Oxidation Reaction on La0.3Sr0.7Fe0.7Cr0.3O3-δ Perovskite as a Solid Oxide Fuel Cell Anode
New Insight into Hydrogen Oxidation Reaction on La0.3Sr0.7Fe0.7Cr0.3O3-δ Perovskite as a Solid Oxide Fuel Cell Anode
复制标题
La0.3Sr0.7Fe0.7Cr0.3O3-δ钙钛矿作为固体氧化物燃料电池阳极的氢氧化反应的新见解
DOI：
10.1149/2.1571704jes
复制
发表时间：
2017-01-01
影响因子：
3.9
通讯作者：
Xu, Qing
中科院分区：
文献类型：
--
作者：
Chen, Min;Chen, Dongchu;Xu, Qing
以固体氧化物燃料电池（SOFC）为研究对象，系统地研究了一种新型钙钛矿型阳极材料La0.3Sr0.7Fe0.7Cr0.3O3-delta（LSFCr-3）上的氢氧化反应（HOR）机理.通过对LSFCr-3基半电池在不同外加直流偏压、氢气（pH 2）和水蒸气分压（pH（2）O）下的电化学阻抗谱研究表明，LSFCr-3钙钛矿上的HOR受氢的解离吸附的速率限制。在pH_2O和pH_2一定的条件下，LSFCr-3表面的氧空位浓度远高于体相。重要的是，对于钙钛矿阳极，证明了水蒸气对氢的解离吸附过程的积极影响。这一发现是由于表面氧空位的水合作用，形成了更多的活性氧阴离子位点。在潮湿的还原性气氛下，LSFCr-3本体的确切组成估计为La0.34Sr0.67Fe0.73 +Cr0.293+O2.65（800 ℃）。在LSFCr-3阳极的表面上，发现B位阳离子（Fe和Cr）的平均氧化态低于本体中的平均氧化态，导致存在Cr 3+、Fe 2+和Fe 3+。表面的Cr 3+由于其在钙钛矿晶格结构中的骨架作用，有助于保持更多的活性氧阴离子用于解离吸附氢。Cr 3+的这种作用被认为对LSFCr-3钙钛矿阳极的电化学性能非常有益。(C)2017年电化学学会。All rights reserved.
Hydrogen oxidation reaction (HOR) mechanisms on a novel perovskite anode with a nominal composition of La0.3Sr0.7Fe0.7Cr0.3O3-delta (LSFCr-3) were systematically investigated for solid oxide fuel cell (SOFC) applications. In terms of electrochemical impedance spectroscopy study of LSFCr-3-based half cells in various applied DC bias, hydrogen (pH2) and water vapor partial pressure (pH(2)O), the HOR on the LSFCr-3 perovskite was suggested to be rate-limited by the dissociative adsorption of hydrogen. At constant pH2O and pH2, the concentration of oxygen vacancies on the LSFCr-3 surface is much higher than that in the bulk. Importantly, a positive impact of water vapor on the process of dissociative adsorption of hydrogen was demonstrated for the perovskite anodes. This finding is explained by the hydration of surface oxygen vacancies, that formed more active oxygen anions sites. Under humid reducing atmosphere, the exact composition of the bulk of the LSFCr-3 is estimated to be La0.34Sr0.67Fe0.73+Cr0.293+O2.65 at 800 degrees C. On the surface of the LSFCr-3 anode, the average oxidation state of B-site cations (Fe and Cr) is found to be lower than that in the bulk, resulting in a presence of Cr3+, Fe2+ and Fe3+. Cr3+ on the surface contributes to holding more active oxygen anions for the dissociative adsorption of hydrogen, due to its backbone action in the perovskite lattice structure. This effect of Cr3+ is suggested to be of great benefit to the electrochemical performance of the LSFCr-3 perovskite anode. (C) 2017 The Electrochemical Society. All rights reserved.