Four hundred hour fuel cell tests were performed on commercial, as-received and Ca²⁺ contaminated catalyst coated membranes (CCMs) to evaluate the effects of long term exposure of foreign cations on fuel cell performance and degradation. Following testing, significant thinning of the cathode catalyst layer was observed across the entire active area in the contaminated cell, while only localized thinning was observed in the as-received baseline CCM. Analysis of the elemental maps and line intensity profiles of platinum (Pt) obtained from energy dispersive X-ray spectrum (EDX) shows minimal change in total platinum content across the thickness of the catalyst layer, and hence loss of carbon is suspected to be the cause of the thinning. A numerical model is employed to show the foreign cation redistribution during testing, which shows proton depletion in the cathode catalyst layer when the CCM is contaminated with foreign cations. We hypothesize that this lack of protons leads to accelerated carbon corrosion in the cathode to supply protons to oxygen reduction where foreign cations block transport of protons. A carbon corrosion scheme is presented which shows that under the operating potentials of the cell, carbon oxidation can occur, leading to the observed thinning.

中文翻译：

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由于外来阳离子污染，聚合物电解质燃料电池中阴极催化剂层的变薄

在商用，原样和Ca ²⁺上进行了400小时的燃料电池测试污染的催化剂涂层膜（CCM），以评估长期暴露于外来阳离子对燃料电池性能和降解的影响。测试后，在受污染的电池的整个活性区域中观察到阴极催化剂层明显变薄，而在原先的基准CCM中仅观察到局部变薄。从能量色散X射线光谱（EDX）获得的铂（Pt）的元素图和线强度分布图的分析显示，整个铂含量在催化剂层的整个厚度上变化很小，因此怀疑碳损失是变薄的原因。使用数值模型来显示测试期间的外来阳离子再分布，当CCM受到外来阳离子污染时，该模型显示了阴极催化剂层中的质子耗竭。我们假设质子的缺乏会导致阴极中碳的加速腐蚀，从而为质子提供氧还原反应，其中外来阳离子会阻止质子的运输。提出了一种碳腐蚀方案，该方案表明，在电池的工作电势下，会发生碳氧化，从而导致观察到的变薄。