Electronic Transport and Corrosion Mechanisms of Graphite-Like Nanocrystalline Carbon Films Used on Metallic Bipolar Plates in Proton-Exchange Membrane Fuel Cells,ACS Applied Materials & Interfaces

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Electronic Transport and Corrosion Mechanisms of Graphite-Like Nanocrystalline Carbon Films Used on Metallic Bipolar Plates in Proton-Exchange Membrane Fuel Cells
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2021-01-12 , DOI: 10.1021/acsami.0c17764
Di Zhang ₁ , Linfa Peng ₁ , Peiyun Yi ₁ , Xinmin Lai _{1,

2}

Affiliation

Nanocrystalline carbon films, which consist of graphite-like nanocrystals within an amorphous carbon matrix, have recently attracted extensive theoretical and experimental attention. Understanding the electronic transport and corrosion mechanisms of graphite-like nanocrystalline carbon films (GNCFs) is essential for their application in proton-exchange membrane fuel cells (PEMFCs). So far, limited progress has been made on the electronic or atomistic understanding of how the degree of structural order and grain boundaries affect the electronic transport and corrosion behaviors of GNCFs. In this work, using the Landauer–Büttiker formula merged with first-principles density functional theory, the conductance of GNCFs is presented as a function of their crystallinity. As the crystallinity decreases, the electron states around the Fermi level are found to be more spatially localized, thus hindering the electronic transport of GNCFs. Additionally, a systemic picture of the chemical reactivity of nanostructured surface in GNCFs toward typical particles existing in PEMFCs is drawn by ab initio molecular dynamics simulations. Systemic experimental investigations on the corrosion mechanisms of GNCFs used in PEMFCs have been conducted in this work. Compared with pure amorphous carbon films, the GNCFs exhibit higher corrosion current densities due to the preferential corrosion in the larger slit pores at the grain boundaries, but their stability in interfacial contact resistance is significantly improved by the embedded graphite-like nanocrystals, which have high levels of resistance to oxygen chemical adsorptions and act as high-speed ways to transport electrons.

中文翻译：

质子交换膜燃料电池中金属双极板上类似石墨的纳米晶碳膜的电子输运和腐蚀机理

由无定形碳基质中的类石墨纳米晶体组成的纳米晶体碳膜最近引起了广泛的理论和实验关注。理解类石墨纳米晶碳膜（GNCF）的电子传输和腐蚀机理，对于其在质子交换膜燃料电池（PEMFC）中的应用至关重要。到目前为止，关于结构有序度和晶界如何影响GNCF的电子迁移和腐蚀行为的电子或原子学理解方面，进展有限。在这项工作中，结合使用Landauer-Büttiker公式和第一原理密度泛函理论，将GNCF的电导率表示为其结晶度的函数。随着结晶度的降低，发现费米能级附近的电子态在空间上更局限，从而阻碍了GNCF的电子传输。此外，通过以下方式得出了GNCF中纳米结构表面对PEMFC中典型颗粒的化学反应性的系统图。从头算分子动力学模拟。在这项工作中，已经对PEMFC中使用的GNCF的腐蚀机理进行了系统的实验研究。与纯无定形碳膜相比，由于在晶界较大的缝隙孔中存在优先腐蚀，GNCF具有更高的腐蚀电流密度，但是通过嵌入的类石墨纳米晶体，其界面接触电阻的稳定性得到了显着提高。级别的抗氧化学吸附性，并作为传输电子的高速方式。

更新日期：2021-01-27

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