Edge‐Rich Fe−N4 Active Sites in Defective Carbon for Oxygen Reduction Catalysis

作者：Xin Wang, Yi Jia, Xin Mao, Daobin Liu, Wenxiang He, Jia Li, Jianguo Liu, Xuecheng Yan, Jun Chen, Li Song, Aijun Du, Xiangdong Yao · 发表于：Advanced Materials · 年份：2020 · DOI：10.1002/adma.202000966 · 被引用次数：317 · 研究领域：Electrocatalysts for Energy Conversion、Fuel Cells and Related Materials、Advanced battery technologies research

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.