Highly accessible and dense surface single metal FeN4 active sites for promoting the oxygen reduction reaction,Energy & Environmental Science

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Highly accessible and dense surface single metal FeN4 active sites for promoting the oxygen reduction reaction
Energy & Environmental Science ( IF 32.4 ) Pub Date : 2022-05-04 , DOI: 10.1039/d2ee00542e
Guangbo Chen ₁ , Yun An _{2,

3} , Shengwen Liu ₄ , Fanfei Sun ₅ , Haoyuan Qi _{1,

6} , Haofei Wu ₇ , Yanghua He ₄ , Pan Liu ₇ , Run Shi ₈ , Jian Zhang ₉ , Agnieszka Kuc ₃ , Ute Kaiser ₆ , Tierui Zhang ₈ , Thomas Heine _{2,

3,

10} , Gang Wu ₄ , Xinliang Feng _{1,

11}

Affiliation

Center for Advancing Electronics Dresden (Cfaed) and Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062, Dresden, Germany
Theoretical Chemistry, Technische Universität Dresden, 01062, Dresden, Germany
Helmholtz-Zentrum Dresden-Rossendorf, Abteilung Ressourcenökologie, Forschungsstelle Leipzig, 04318, Leipzig, Germany
Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA
Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201204, P. R. China
Department of Electron Microscopy of Material Science, Central Facility for Electron Microscopy, University of Ulm, Ulm, 89081, Germany
School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 200230, Shanghai, P. R. China
Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
Department of Applied Chemistry, School of Applied and Natural Sciences, Northwestern Polytechnical University, Xi’an, 710129, P. R. China
Department of Chemistry, Yonsei University, Seoul, 03722, Republic of Korea
Department of Synthetic Materials and Functional Devices, Max Planck Institute of Microstructure Physics, D-06120, Halle (Saale), Germany

Single iron atom and nitrogen-codoped carbon (Fe–N–C) electrocatalysts, which have great potential to catalyze the kinetically sluggish oxygen reduction reaction (ORR), have been recognized as the most promising alternatives to the precious metal platinum. Unfortunately, the ORR properties of the existing Fe–N–C catalysts are significantly hampered by the inferior accessibility and intrinsic activity of FeN₄ moieties. Here, we constructed densely exposed surface FeN₄ moieties on a hierarchically porous carbon (sur-FeN₄-HPC) by Fe ion anchoring and a subsequent pyrolysis strategy using the nitrogen-doped hierarchically porous carbon (NHPC) as the scaffold. The high surface area of the NHPC with abundant surface Fe anchoring sites enabled the successful fabrication of densely accessible FeN₄ active moieties (34.7 × 10¹⁹ sites g⁻¹) on sur-FeN₄-HPC. First-principles calculations further suggested that the edge effect could regulate the electronic structure of the single Fe site, hence promoting the intrinsic ORR activity of the FeN₄ moiety. As a result, the sur-FeN₄-HPC electrocatalyst exhibited excellent ORR activity in acidic media with a high half-wave potential of 0.83 V (vs. the reversible hydrogen electrode). We further examined sur-FeN₄-HPC as a cathode catalyst in proton exchange membrane fuel cells (PEMFCs). The membrane electrode assembly delivered a high current density of 24.2 mA cm⁻² at 0.9 V_iR-free (internal resistance-compensated voltage) under 1.0 bar O₂ and a maximum peak power density of 0.412 W cm⁻² under 1.0 bar air. Importantly, the catalyst demonstrated promising durability during 30 000 voltage cycles under harsh H₂ and air conditions. The PEMFC performance of sur-FeN₄-HPC outperforms those of the previously reported Fe–N–C electrocatalysts. The engineering of highly accessible and dense surface FeN₄ sites on sur-FeN₄-HPC offers a fruitful pathway for designing high-performance electrocatalysts for different electrochemical processes.

中文翻译：

用于促进氧还原反应的高度可及且致密的表面单金属 FeN4 活性位点

单铁原子和氮共掺杂碳 (Fe-N-C) 电催化剂具有催化动力学缓慢的氧还原反应 (ORR) 的巨大潜力，已被认为是贵金属铂最有希望的替代品。不幸的是，现有 Fe-N-C 催化剂的 ORR 特性受到 FeN ₄部分较差的可及性和内在活性的显着阻碍。在这里，我们在分级多孔碳 ( sur -FeN ₄ ) 上构建了密集暴露的表面 FeN ₄-HPC）通过铁离子锚定和随后的热解策略，使用氮掺杂的分级多孔碳（NHPC）作为支架。NHPC 的高表面积具有丰富的表面 Fe 锚定位点，能够在sur -FeN _{4 -HPC 上成功制造密集可接近的 FeN}₄活性部分（34.7 × 10 ¹⁹个位点 g ^-1）。第一性原理计算进一步表明边缘效应可以调节单个Fe位点的电子结构，从而促进FeN ₄部分的内在ORR活性。结果，sur -FeN ₄-HPC电催化剂在酸性介质中表现出优异的ORR活性，半波电位为0.83 V（与可逆氢电极相比）。我们进一步研究了sur -FeN ₄ -HPC 作为质子交换膜燃料电池 (PEMFC) 中的阴极催化剂。_{膜电极组件在 1.0 bar O 2}下在 0.9 V _iR-free（内部电阻补偿电压）下提供 24.2 mA cm ^-2的高电流密度，在 1.0 bar 空气下提供 0.412 W cm ^{-2的最大峰值功率密度。}_{重要的是，在恶劣的 H 2}和空气条件下，该催化剂在 30 000 次电压循环期间表现出良好的耐久性。PEMFC 的性能sur -FeN ₄ -HPC 优于先前报道的 Fe-N-C 电催化剂。sur -FeN ₄ -HPC上高度可及且致密的表面 FeN 4 位点的工程_设计为设计用于不同电化学过程的高性能电催化剂提供了一条富有成效的途径。

更新日期：2022-05-04

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