Available Active Sites on ε-Fe3N Nanoparticles Synthesized by a Facile Route for Hydrogen Evolution Reaction,Advanced Materials Interfaces

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Available Active Sites on ε-Fe3N Nanoparticles Synthesized by a Facile Route for Hydrogen Evolution Reaction
Advanced Materials Interfaces ( IF 4.3 ) Pub Date : 2021-04-30 , DOI: 10.1002/admi.202100070
Ruo Qiang ₁ , Hui Wang ₁ , Kang Xu ₂ , Qunyao Yuan ₁ , Youxing Yu ₁ , Lei Li ₃ , Jiaou Wang ₄ , Lirong Zheng ₄ , Peter C. Sherrell _{5,

6} , Jun Chen ₆ , Xiaofang Bi ₁

Affiliation

Exploring efficient noble-metal-free water-splitting electrocatalysts from earth-abundant elements is of great importance to realize wide applications in the generation of hydrogen fuel for clean energy. Here, a facile route is reported to synthesize ε-Fe₃N single-phase nanoparticles by thermal ammonolysis of Fe precursors. The roles of nitrogen atoms in tailoring the hydrogen evolution reaction (HER) activities of ε-Fe₃N have been systematically investigated. HER activity is enhanced by reducing the effective coordination number of nitrogen atoms from 2.61 to 1.67, where the standard coordination number in ε-Fe₃N is 2. Density functional theory calculations reveal that the reduction of nitrogen content lowers the energy of Tafel process on the (

\bar{1}

100)-FeN-exposed and (11

\bar{2}

0) N-exposed surfaces. Both surfaces are thermodynamically favored for the HER. Furthermore, the active sites of Tafel process change from the kinetically less favored hollow sites of Fe atoms to the kinetically more favored top site of N atoms and the bridge site of Fe atoms on both (

\bar{1}

100)-FeN and (11

\bar{2}

0) N-exposed surfaces. The findings propose a novel strategy to enhance HER activity by using nitrogen deficiency, which is of great importance for the development of highly active transition metal based electrocatalysts.

中文翻译：

通过简便的析氢反应途径合成的 ε-Fe3N 纳米颗粒上的可用活性位点

从地球丰富的元素中探索高效的不含贵金属的水分解电催化剂对于实现清洁能源氢燃料的广泛应用具有重要意义。在这里，报道了一种通过 Fe 前驱体的热氨解合成 ε-Fe ₃ N 单相纳米粒子的简便途径。已经系统地研究了氮原子在调节 ε-Fe ₃ N的析氢反应 (HER) 活性中的作用。通过将氮原子的有效配位数从 2.61 降低到 1.67 来增强 HER 活性，其中 ε-Fe ₃ N中的标准配位数为 2。密度泛函理论计算表明，氮含量的减少降低了 Tafel 过程的能量这（