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Active‐Site Imprinting: Preparation of Fe–N–C Catalysts from Zinc Ion–Templated Ionothermal Nitrogen‐Doped Carbons
Author(s) -
Menga Davide,
RuizZepeda Francisco,
Moriau Léonard,
Šala Martin,
Wagner Friedrich,
Koyutürk Burak,
Bele Marjan,
Petek Urša,
Hodnik Nejc,
Gaberšček Miran,
Fellinger TimPatrick
Publication year - 2019
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201902412
Subject(s) - catalysis , materials science , electrochemistry , inorganic chemistry , highly oriented pyrolytic graphite , metal , polyoxometalate , chemical engineering , nanotechnology , chemistry , electrode , organic chemistry , scanning tunneling microscope , engineering , metallurgy
Atomically dispersed Fe–N–C catalysts are considered the most promising precious‐metal‐free alternative to state‐of‐the‐art Pt‐based oxygen reduction electrocatalysts for proton‐exchange membrane fuel cells. The exceptional progress in the field of research in the last ≈30 years is currently limited by the moderate active site density that can be obtained. Behind this stands the dilemma of metastability of the desired FeN 4 sites at the high temperatures that are believed to be a requirement for their formation. It is herein shown that Zn 2+ ions can be utilized in the novel concept of active‐site imprinting based on a pyrolytic template ion reaction throughout the formation of nitrogen‐doped carbons. As obtained atomically dispersed Zn–N–Cs comprising ZnN 4 sites as well as metal‐free N 4 sites can be utilized for the coordination of Fe 2+ and Fe 3+ ions to form atomically dispersed Fe–N–C with Fe loadings as high as 3.12 wt%. The Fe–N–Cs are active electocatalysts for the oxygen reduction reaction in acidic media with an onset potential of E 0 = 0.85 V versus RHE in 0.1 m HClO 4 . Identical location atomic resolution transmission electron microscopy imaging, as well as in situ electrochemical flow cell coupled to inductively coupled plasma mass spectrometry measurements, is employed to directly prove the concept of the active‐site imprinting approach.