武汉大学翟月明团队揭示了硫掺杂Fe-N-C单原子催化剂增强氧还原活性的起源于铁自旋态调谐效应。相关研究成果于2021年9月22日发表在国际顶尖学术期刊《德国应用化学》。

掺杂杂原子的原子分散Fe1-NC催化剂表现出优异的氧还原反应活性。然而，增强活性的根本原因仍然存在争议，因为支配增强的结构-功能关系仍然难以捉摸。

该文中，以硫掺杂的Fe1-NC催化剂为模型，与传统的Fe-NC材料相比，其ORR活性更高。⁵⁷Fe穆斯堡尔谱和电子顺磁共振谱表明，在Fe1-NC的第二配位球中加入S可以诱导自旋极化构型的转变。Operato ⁵⁷Fe穆斯堡尔谱确定C-FeN 4-S部分的低自旋单Fe³⁺原子为ORR的活性中心。此外，DFT计算揭示了S掺杂后Fe中心的低自旋态促进了OH*脱附过程。

该研究工作阐明了S掺杂增强ORR活性的潜在机制，并为研究更广泛的杂原子掺杂Fe1-NC催化剂的功能奠定了基础，从而为自旋态决定的ORR提供了通用指导。

附：英文原文

Title: Unraveling the Origin of Sulfur-doped Fe-N-C Single Atom Catalyst for Enhanced Oxygen Reduction Activity: Effect of Fe-spin State Tuning

Author: Zhaoyang Chen, Huan Niu, Jie Ding, Heng Liu, Pei-Hsuan Chen, Yi-Hsuan Lu, Ying-Rui Lu, Wenbin Zuo, Lei Han, Yuzheng Guo, Sung-Fu Hung, Yueming Zhai

Issue&Volume: 2021-09-22

Abstract: Heteroatom doped atomically dispersed Fe  1  -NC catalysts have been found to show excellent activity toward oxygen reduction reaction (ORR). However, the origin of the enhanced activity is still controversial because the structure-function relationship governing the enhancement remains elusive. Herein, sulfur(S)-doped Fe  1  -NC catalyst was obtained as a model, which displays a superior activity for ORR towards the traditional Fe-NC materials.  57  Fe Mssbauer spectroscopy and electron paramagnetic resonance spectroscopy revealed that incorporation of S in the second coordination sphere of Fe  1  -NC can induce the transition of spin polarization configuration. Operando  57  Fe Mssbauer spectra definitively identified the low spin  single-Fe  3+  -atom of C-FeN  4  -S moiety as the active site for ORR. Moreover, DFT calculations unveiled that lower spin state of the Fe center after the S doping promotes OH* desorption process. This work elucidates the underlying mechanisms towards S doping for enhancing ORR activity, and paves a way to investigate the function of broader heteroatom doped Fe  1  -NC catalysts to offer a general guideline for spin-state-determined ORR.

DOI: 10.1002/anie.202110243

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202110243