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Elucidating the Structural Composition of an Fe–N–C Catalyst by Nuclear‐ and Electron‐Resonance Techniques
Author(s) -
Wagner Stephan,
Auerbach Hendrik,
Tait Claudia E.,
Martinaiou Ioanna,
Kumar Shyam C. N.,
Kübel Christian,
Sergeev Ilya,
Wille HansChristian,
Behrends Jan,
Wolny Juliusz A.,
Schünemann Volker,
Kramm Ulrike I.
Publication year - 2019
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201903753
Subject(s) - catalysis , leaching (pedology) , pyrolysis , metal , oxide , composition (language) , characterization (materials science) , materials science , iron oxide , work (physics) , chemistry , chemical engineering , inorganic chemistry , nanotechnology , metallurgy , organic chemistry , physics , philosophy , linguistics , environmental science , soil science , engineering , soil water , thermodynamics
Fe–N–C catalysts are very promising materials for fuel cells and metal–air batteries. This work gives fundamental insights into the structural composition of an Fe–N–C catalyst and highlights the importance of an in‐depth characterization. By nuclear‐ and electron‐resonance techniques, we are able to show that even after mild pyrolysis and acid leaching, the catalyst contains considerable fractions of α‐iron and, surprisingly, iron oxide. Our work makes it questionable to what extent FeN 4 sites can be present in Fe–N–C catalysts prepared by pyrolysis at 900 °C and above. The simulation of the iron partial density of phonon states enables the identification of three FeN 4 species in our catalyst, one of them comprising a sixfold coordination with end‐on bonded oxygen as one of the axial ligands.