Nafion thickness dependence of H2O2 yield during O2 reduction at Nafion/Pt microelectrode studied by scanning electrochemical microscopy
Nafion thickness dependence of H2O2 yield during O2 reduction at Nafion/Pt microelectrode studied by scanning electrochemical microscopy
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DOI：
10.1016/j.electacta.2013.07.046
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发表时间：
2013-12
影响因子：
6.6
通讯作者：
S. Shironita;Tsukasa Sakai;M. Umeda
中科院分区：
文献类型：
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作者：
S. Shironita;Tsukasa Sakai;M. Umeda
在聚合物电解质燃料电池（PEFC）的Pt阴极进行O2还原反应（ORR）时，会产生少量的H2 O2副产物。产生的H2 O2由于其腐蚀性而使聚合物电解质膜和Pt电极劣化。据报道，在电催化剂层中使用的H2 O2的量和离聚物的量之间存在关系。为了澄清这种关系，我们采用了Pt微盘电极，以便可以均匀地控制Nafion涂层的厚度。H2 O2的量，然后相对于外涂的Nafion厚度进行了研究。在ORR期间在Nafion涂覆的Pt发生器处产生的H2 O2在扫描电化学显微镜的Pt检测器处被氧化。结果表明，H2 O2的检测电流随着Nafion膜厚度的增加而增加，直到0.16 μm。然后，在较厚的Nafion区域中，电流减小。在薄的Nafion/Pt的H2 O2的增加可以解释为减少的数量的Pt-Pt对网站的ORR。对于较厚区域中的H2 O2减少，H2 O2在Nafion层中的低扩散系数使得难以扩散。
During the O2reduction reaction (ORR) at the Pt cathode of a polymer electrolyte fuel cell (PEFC), a slight amount of H2O2is produced as a by-product. The generated H2O2degrades the polymer electrolyte membrane and Pt electrode due to its corrosive nature. It is reported that a relationship exists between the amount of H2O2and an amount of ionomer used in an electrocatalyst layer. To clarify the relationship, we employed a Pt microdisk electrode so that the Nafion-coated thickness could be uniformly controlled. The H2O2amount was then investigated with respect to the overcoated Nafion thickness. The generated H2O2at the Nafion-coated Pt generator during the ORR is oxidized at a Pt detector of the scanning electrochemical microscope. As a result, the H2O2detection current increased with the increasing Nafion thickness up to 0.16 μm. The current then decreased in the thicker Nafion region. The H2O2increase at the thin Nafion/Pt can be explained by a decrease in the number of Pt–Pt pair-sites for the ORR. For the H2O2decrease in the thicker region, a low diffusion coefficient of H2O2in the Nafion layer makes it difficult to spread out.