arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1407.7384cond-mat.mtrl-sci
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负载型polymer电解质超薄膜形貌的数值研究

Morphology of supported polymer electrolyte ultra-thin films: a numerical study

Daiane Damasceno Borges, Gerard Gebel, Alejandro A. Franco, Kourosh Malek, Stefano Mossa

摘要:

聚合物电解质膜(PEM)的形态,例如,在PEM燃料电池催化剂层内的Nafion对决定电池性能的电化学活性和传输现象具有显著影响。在这些区域中,可以发现Nafion作为超薄膜,涂覆催化剂和催化剂载体表面。这些表面的亲水/疏水特性对膜的结构形成的影响尚未得到充分探讨。在这里,我们报告了关于分子动力学模拟调查的基板上的离聚物超薄膜形态在不同的水化水平的影响。我们使用一个平均场的模型,我们在以前的出版物中介绍的水合Nafion离聚物与基板的相互作用,其特征在于可调程度的亲水性。我们发现,基板与水的亲和力起着至关重要的作用,在离聚物膜的分子重排,导致完全不同的形态。在电影的不同区域的详细结构描述显示出强烈的异质性行为的证据。最后,我们的观察PEMFC催化剂层性能的影响的定性讨论。

英文摘要:

Morphology of polymer electrolytes membranes (PEM), e.g., Nafion, inside PEM fuel cell catalyst layers has significant impact on the electrochemical activity and transport phenomena that determine cell performance. In those regions, Nafion can be found as an ultra-thin film, coating the catalyst and the catalyst support surfaces. The impact of the hydrophilic/hydrophobic character of these surfaces on the structural formation of the films has not been sufficiently explored yet. Here, we report about Molecular Dynamics simulation investigation of the substrate effects on the ionomer ultra-thin film morphology at different hydration levels. We use a mean-field-like model we introduced in previous publications for the interaction of the hydrated Nafion ionomer with a substrate, characterized by a tunable degree of hydrophilicity. We show that the affinity of the substrate with water plays a crucial role in the molecular rearrangement of the ionomer film, resulting in completely different morphologies. Detailed structural description in different regions of the film shows evidences of strongly heterogeneous behavior. A qualitative discussion of the implications of our observations on the PEMFC catalyst layer performance is finally proposed.

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