Ordered Hierarchically Micro- and Mesoporous Fe-Nx-Embedded Graphitic Architectures as Efficient Electrocatalysts for Oxygen Reduction Reaction
Ordered Hierarchically Micro- and Mesoporous Fe-Nx-Embedded Graphitic Architectures as Efficient Electrocatalysts for Oxygen Reduction Reaction
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DOI：
10.1021/cs401257j
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发表时间：
2014-06-01
期刊：
影响因子：
12.9
通讯作者：
Shan, Yongkui
中科院分区：
文献类型：
--
作者：
Kong, Aiguo;Zhu, Xiaofang;Shan, Yongkui
在SBA-15的介孔孔道中，通过简单热解不同的氮杂环化合物和氯化铁，直接制备了一系列新型的分级有序的微米和介孔Fe-N-x嵌入石墨结构（Fe-N-GC）.在这些多孔Fe-N-GC材料中，由2，2-联吡啶和Fe螯合物在900 ℃加热制备的样品在0.1M KOH中的ORR起始电位和半波电位（E1/2）值比商业Pt-C催化剂更正，这说明它是已报道的碱性介质中非贵金属催化剂（NPMCs）中最有前途的一种。此外，与氮掺杂的碳和Co 3 O 4/碳复合材料不同，高ORR电流密度（5.2 mA cm（-2），0.6 V），催化剂负载量为0.6 mg cm（-2），其比具有20 μ g（Pt）cm（-2）负载的商业Pt/C电极上的电流大约0.6mA cm（-2）。此外，活性部分在石墨框架中的有效嵌入和ORR中的直接四电子还原途径有助于其在碱性和酸性介质中的高耐久性。其优异的ORR活性应归因于活性位点密度与质量和电荷传输能力之间的优化平衡。这种分级多孔的Fe-N-x-石墨材料在质子交换膜燃料电池的阴极催化剂层的实际应用中具有很大的前景。
A series of novel ordered hierarchically micro- and mesoporous Fe-N-x-embedded graphitic architectures (Fe-N-GC) are directly prepared by the simple pyrolysis of the different nitrogen heterocyclic compounds and iron chlorides in the confined mesochannels of SBA-15. Among these porous Fe-N-GC materials, the sample prepared by heating 2,2-bipyridine and Fe chelates at 900 degrees C shows the more positive ORR onset potential and half-wave potential (E 1/2) values than commercial Pt-C catalysts in 0.1 M KOH, which illustrate that it is one of the most-promising nonprecious metal catalysts (NPMCs) among the reported NMPCs in alkaline medium. Moreover, unlike nitrogen-doped carbons and Co3O4/carbon composites, high ORR current density (5.2 mA cm(-2), 0.6 V) over this Fe-N-GC electrode with catalyst loading of 0.6 mg cm(-2) can be also obtained in 0.1 M HCIO4 acidic solution, which is about 0.6 mA cm(-2) larger than that over the electrode of commercial Pt/C with 20 mu g(pt) cm(-2) loading. In addition, the effective embedding of active moieties in the graphitic frameworks and a direct four-electron reduction pathway in ORR contributes to its high durability in both alkaline and acidic media. Its excellent ORR activity should be ascribed to the optimized balance between active site density and capability for mass and charge transport. Such hierarchically porous Fe-N-x-graphitic materials hold great promise for the practical utilization in cathode catalyst layers of proton exchange membrane fuel cells.