Wang Xin, Jia Yi, Mao Xin, Liu Daobin, He Wenxiang, Li Jia, Liu Jianguo, Yan Xuecheng, Chen Jun, Song Li, Du Aijun, Yao Xiangdong
School of Environment and Science, Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan Campus, Queensland, 4111, Australia.
School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Queensland, 4000, Australia.
Adv Mater. 2020 Apr;32(16):e2000966. doi: 10.1002/adma.202000966. Epub 2020 Mar 5.
Controllably constructing nitrogen-modified divacancies (ND) in carbon substrates to immobilize atomic Fe species and unveiling the advantageous configuration is still challenging, but indispensable for attaining optimal Fe-N-C catalysts for the oxygen reduction reaction (ORR). Herein, a fundamental investigation of unfolding intrinsically superior edge-ND trapped atomic Fe motifs (e-ND-Fe) relative to an intact center model (c-ND-Fe) in ORR electrocatalysis is reported. Density functional theory calculations reveal that local electronic redistribution and bandgap shrinkage for e-ND-Fe endow it with a lower free-energy barrier toward direct four-electron ORR. Inspired by this, a series of atomic Fe catalysts with adjustable ND-Fe coordination are synthesized, which verify that ORR performance highly depends on the concentration of e-ND-Fe species. Remarkably, the best e-ND-Fe catalyst delivers a favorable kinetic current density and halfwave potential that can be comparable to benchmark Pt-C under acidic conditions. This work will guide to develop highly active atomic metal catalysts through rational defect engineering.
在碳基材料中可控地构建氮修饰的双空位（ND）以固定原子铁物种并揭示其优势构型仍然具有挑战性，但对于获得用于氧还原反应（ORR）的最佳铁氮碳催化剂而言不可或缺。在此，我们报道了一项关于在ORR电催化中展开本质上更优越的边缘-ND捕获原子铁基序（e-ND-Fe）相对于完整中心模型（c-ND-Fe）的基础研究。密度泛函理论计算表明，e-ND-Fe的局部电子重新分布和带隙收缩使其对直接四电子ORR具有更低的自由能垒。受此启发，合成了一系列具有可调节的ND-Fe配位的原子铁催化剂，证实了ORR性能高度依赖于e-ND-Fe物种的浓度。值得注意的是，最佳的e-ND-Fe催化剂在酸性条件下具有与基准Pt-C相当的良好动力学电流密度和半波电位。这项工作将指导通过合理的缺陷工程开发高活性原子金属催化剂。
