Unraveling the Origin of Sulfur-Doped Fe-N-C Single-Atom Catalyst for Enhanced Oxygen Reduction Activity: Effect of Iron Spin-State Tuning

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*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

Heteroatom doped atomically dispersed Fe1-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 Fe1-NC catalyst was obtained as a model, which displays a superior activity for ORR towards the traditional Fe-NC materials. 57Fe Mössbauer spectroscopy and electron paramagnetic resonance spectroscopy revealed that incorporation of S in the second coordination sphere of Fe1-NC can induce the transition of spin polarization configuration. Operando 57Fe Mössbauer spectra definitively identified the low spin single-Fe3+-atom of C-FeN4-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 Fe1-NC catalysts to offer a general guideline for spin-state-determined ORR.

Original languageEnglish
Pages (from-to)25404-25410
Number of pages7
JournalAngewandte Chemie - International Edition
Volume60
Issue number48
DOIs
StatePublished - 22 Nov 2021

Keywords

  • iron
  • Mössbauer spectroscopy
  • oxygen reduction reaction
  • spin states
  • sulfur

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