“Theoretical investigation on degradation mechanism of hydrated Nafion membrane”
“Theoretical investigation on degradation mechanism of hydrated Nafion membrane”
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“水合Nafion膜降解机理的理论研究”
DOI：
10.1021/acsomega.7b00594
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发表时间：
2017
期刊：
影响因子：
4.1
通讯作者：
K. Miyatake
中科院分区：
文献类型：
--
作者：
T. Tsuneda;Raman K. Singh;A. Iiyama;K. Miyatake
提出了水合Nafion膜通过侧链醚键解离的h2o2诱导降解机理。虽然质子交换膜燃料电池的耐久性明显取决于膜的降解速率，但其降解机制仍未得到解决。通常认为降解的主要方式涉及OH•自由基；相反，我们在这里表明h2o2诱导的降解机制更有可能。根据最新的理论计算和与实验结果的详细比较，我们提出了水合Nafion膜的这种机制，通过侧链的醚键的解离进行，活化能相对较低。在该机理中，得到(H2O)λ ho3s - cf2 - cf2 - o - o - h （λ为水化数）作为关键降解片段。随后可能的分解反应机制也阐明了该片段。计算得到的中间体和产物的振动谱与实验红外光谱一致。进一步考虑这种h2o2介导的降解机制可以极大地促进寻找对抗膜降解的方法。
A H2O2-induced degradation mechanism is presented for the hydrated Nafion membrane proceeding through the dissociation of the ether linkages of the side chains. Although the durability of proton-exchange membrane fuel cells clearly depends on the degradation rate of the membrane, typically Nafion, the degradation mechanism still has not been resolved. It has often been assumed that the principal mode of degradation involves OH•radicals; in contrast, we show here that a H2O2-induced degradation mechanism is more likely. On the basis of state-of-the-art theoretical calculations and detailed comparison with experimental results, we present such a mechanism for the hydrated Nafion membrane, proceeding through the dissociation of the ether linkage of the side chains, with a relatively low activation energy. In this mechanism, (H2O)λHO3S–CF2–CF2–O–O–H (λ is the hydration number) is obtained as a key degradation fragment. Possible subsequent decomposition-reaction mechanisms are also elucidated for this fragment. The calculated vibrational spectra for the intermediates and products proposed in these mechanisms were found to be consistent with the experimental IR spectra. Further consideration of this H2O2-mediated degradation mechanism could greatly facilitate the search for ways to combat membrane degradation.