A Versatile Approach to Boost Oxygen Reduction of Fe-N4 Sites by Controllably Incorporating Sulfur Functionality,Advanced Functional Materials

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A Versatile Approach to Boost Oxygen Reduction of Fe-N4 Sites by Controllably Incorporating Sulfur Functionality
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2021-04-15 , DOI: 10.1002/adfm.202100833
Chunfeng Shao ₁ , Lingmin Wu ₁ , Haocheng Zhang ₁ , Qike Jiang ₂ , Xiaoyan Xu ₂ , Yinghua Wang ₁ , Shiguang Zhuang ₁ , Hailiang Chu ₃ , Lixian Sun ₃ , Jianshan Ye ₁ , Baitao Li ₁ , Xiujun Wang ₁

Affiliation

Although atomically dispersed Fe-N₄ on carbon materials (Fe-NC) have enormous potential for the oxygen reduction reaction (ORR), precise control over the electronic structure of Fe to enhance the catalytic performance and a full understanding of the catalytic mechanism remain elusive. Herein, a novel approach is designed to boost the kinetic activity of single Fe-N₄ centers by controlling S-doped content and species (namely, thiophene-like S and oxidized S). Due to confinement and catalysis effects, the innovative strategy of combining a Mg(OH)₂ template with KOH activation preferentially generates oxidized S and simultaneously constructs porous carbon with a high Fe loading (2.93 wt%) and hierarchical pores. Theoretical calculations suggest that neighboring S functionalities can affect the electronic configurations of Fe-N₄ sites and increase the electron density around Fe atoms, thereby optimizing the adsorption energy of intermediates and substantially accelerating reaction kinetics, following the trend: oxidized S doped > thiophene-like S doped > pristine Fe-N₄. Benefiting from high activity and accessibility of Fe-N₄ sites, the optimal FeNC-SN-2 electrode displays impressive ORR activity with large power density while maintaining outstanding durability in Zn-air batteries and microbial fuel cells. The work paves the way to prepare stable single-atom metal-N_x sites with heteroatom-doping for diverse high-performance applications.

中文翻译：

通过可控地结合硫功能来促进 Fe-N4 位点氧还原的通用方法

尽管原子分散的 Fe-N ₄在碳材料 (Fe-NC) 上具有巨大的氧还原反应 (ORR) 潜力，但精确控制 Fe 的电子结构以提高催化性能和对催化机制的全面了解仍然难以捉摸. 在此，设计了一种新方法通过控制 S 掺杂的含量和种类（即类噻吩 S 和氧化 S）来提高单个 Fe-N ₄中心的动力学活性。由于限制和催化作用，结合 Mg(OH) ₂的创新策略具有 KOH 活化的模板优先生成氧化的 S 并同时构建具有高 Fe 负载（2.93 wt%）和分级孔的多孔碳。理论计算表明，相邻的 S 官能团可以影响 Fe-N ₄位点的电子构型并增加 Fe 原子周围的电子密度，从而优化中间体的吸附能并显着加速反应动力学，遵循以下趋势：氧化 S 掺杂 > 噻吩-如 S 掺杂 > 原始 Fe-N ₄。受益于 Fe-N _{4 的}高活性和可及性在现场，最佳的 FeNC-SN-2 电极显示出令人印象深刻的 ORR 活性和大功率密度，同时在锌空气电池和微生物燃料电池中保持出色的耐久性。这项工作为制备稳定的单原子金属-N _x位点和杂原子掺杂铺平了道路，用于各种高性能应用。

更新日期：2021-06-18

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