Assisting Atomic Dispersion of Fe in N-Doped Carbon by Aerosil for High-Efficiency Oxygen Reduction

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DOI

  • Tete Zhao, China University of Petroleum (East China)
  • ,
  • Anuj Kumar, GLA University
  • ,
  • Xuya Xiong
  • Mang Ma, China University of Petroleum (East China)
  • ,
  • Yiyan Wang, China University of Petroleum (East China)
  • ,
  • Ying Zhang, China University of Petroleum (East China)
  • ,
  • Stefano Agnoli, University of Padova
  • ,
  • Guoxin Zhang, Shandong University of Science and Technology
  • ,
  • Xiaoming Sun, China University of Petroleum (East China), Beijing University of Chemical Technology

Utilizing Zn as a "fencing" agent has enabled the pyrolytic synthesis of atomically dispersed metal-nitrogen-carbon (AD-MNC) materials for broad electrocatalysis such as fuel cells, metal-air batteries, and water electrolyzers. Yet the Zn residue troubles the precise identification of the responsible sites in active service. Herein we developed a simple aerosil-assisted method for preparing AD-MNC materials to cautiously avoid the introduction of Zn. The combined analysis of extended X-ray absorption fine structure (EXAFS) and aberration-corrected high-resolution transition electron microscopy verified the atomic dispersion of Fe species in the as-made Fe-NC sample with a well-defined structure of Fe-N4. Besides, the EXAFS studies indicated the formation of oxygenated Fe-N4 moieties (O-Fe-N4) after the removal of aerosil nanoparticles. Therefore, the immobilization of Fe atoms in the carbon substrate was attributed to the heavily doping N and rich oxygen dangling species at the aerosil surface. Electrochemical measurements revealed that the as-made Fe-NC material furnished with O-Fe-N4 moieties exhibited excellent oxygen reduction reaction (ORR) performance, characterized by individually indicating ∼22 mV higher half-wave potentials, with respect to commercial Pt/C catalyst. Density functional theory (DFT) computations suggested that the dangling oxygen ligand on the Fe-N4 moiety could significantly boost the cleavage of OOH* and the reductive release of *OH intermediates, leading to the enhancement of overall ORR performance.

Original languageEnglish
JournalACS applied materials & interfaces
Volume12
Issue23
Pages (from-to)25832-25842
Number of pages11
ISSN1944-8244
DOIs
Publication statusPublished - Jun 2020

    Research areas

  • aerosil, atomic dispersion, carbon materials, iron−nitrogen−carbon, oxygen reduction reaction

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