The Marriage of the FeN4 Moiety and MXene Boosts Oxygen Reduction Catalysis: Fe 3d Electron Delocalization Matters,Advanced Materials

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The Marriage of the FeN4 Moiety and MXene Boosts Oxygen Reduction Catalysis: Fe 3d Electron Delocalization Matters
Advanced Materials ( IF 27.4 ) Pub Date : 2018-09-10 , DOI: 10.1002/adma.201803220
Zilan Li ₁ , Zechao Zhuang ₁ , Fan Lv ₂ , Han Zhu ₃ , Liang Zhou ₁ , Mingchuan Luo ₂ , Jiexin Zhu ₁ , Zhiquan Lang ₁ , Shihao Feng ₁ , Wei Chen ₁ , Liqiang Mai ₁ , Shaojun Guo ₂

Affiliation

Iron–nitrogen–carbon (Fe–N–C) is hitherto considered as one of the most satisfactory alternatives to platinum for the oxygen reduction reaction (ORR). Major efforts currently are devoted to the identification and maximization of carbon‐enclosed FeN₄ moieties, which act as catalytically active centers. However, fine‐tuning of their intrinsic ORR activity remains a huge challenge. Herein, a twofold activity improvement of pristine Fe–N–C through introducing Ti₃C₂T_x MXene as a support is realized. A series of spectroscopy and magnetic measurements reveal that the marriage of FeN₄ moiety and MXene can induce remarkable Fe 3d electron delocalization and spin‐state transition of Fe(II) ions. The lower local electron density and higher spin state of the Fe(II) centers greatly favor the Fe

d_{z^{2}}

electron transfer, and lead to an easier oxygen adsorption and reduction on active FeN₄ sites, and thus an enhanced ORR activity. The optimized catalyst shows a two‐ and fivefold higher specific ORR activity than those of pristine catalyst and Pt/C, respectively, even exceeding most Fe–N–C catalysts ever reported. This work opens up a new pathway in the rational design of Fe–N–C catalysts, and reflects the critical influence of Fe 3d electron states in FeN₄ moiety supported on MXene in ORR catalysis.

中文翻译：

FeN4部分和MXene的结合促进了氧还原催化：Fe 3d电子离域化很重要

迄今为止，铁-氮-碳（Fe-N-C）被认为是用于氧还原反应（ORR）的最令人满意的铂替代品之一。目前，人们致力于识别和最大化碳封入的FeN ₄部分，这些部分起着催化活性中心的作用。但是，对其固有的ORR活动进行微调仍然是一个巨大的挑战。在此，通过引入Ti ₃ C ₂ T _x MXene作为载体，实现了原始Fe–N–C活性的双重提高。一系列的光谱学和磁性测量表明，FeN _4的结合部分和MXene可以诱导Fe（II）离子发生显着的Fe 3d电子离域和自旋态跃迁。Fe（II）中心的较低局部电子密度和较高的自旋态极大地有利于Fe

d_{ž^{2个}}

电子转移，并导致更容易的氧气吸附并还原到活性FeN ₄位上，因此增强了ORR活性。优化的催化剂分别比原始催化剂和Pt / C的ORR活性高2到5倍，甚至超过了以往报道的大多数Fe–N–C催化剂。这项工作为Fe–N–C催化剂的合理设计开辟了一条新途径，并反映了ORR催化中MXene负载的FeN ₄部分中Fe 3d电子态的关键影响。

更新日期：2018-09-10

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