One-Step Preparation of Fe/N/C Single-Atom Catalysts Containing Fe-N 4 Sites from an Iron Complex Precursor with 5,6,7,8-Tetraphenyl-1,12-Diazatriphenylene Ligands.

Authors :: Matsumoto K
Kato M
Yagi I
Xie S
Asakura K
Noro SI
Tohnai N
Campidelli S
Hayashi T
Onoda A
Source :: Chemistry (Weinheim an der Bergstrasse, Germany) [Chemistry] 2022 Jan 24; Vol. 28 (5), pp. e202103545. Date of Electronic Publication: 2021 Dec 18.
Publication Year :: 2022
Abstract: Fe/N/C single-atom catalysts containing Fe-N <subscript>x</subscript> sites prepared by pyrolysis are promising cathode materials for fuel cells and metal-air batteries due to their high oxygen reduction reaction (ORR) activities. We have developed iron complexes containing N2- or N3-chelating coordination structures with preorganized aromatic rings in a 1,12-diazatriphenylene framework tethering bromo substituents as precursors to precisely construct Fe-N <subscript>4</subscript> sites in an Fe/N/C catalyst. One-step pyrolysis of the iron complex with carbon black forms atomically dispersed Fe-N <subscript>4</subscript> sites without iron aggregates. X-ray absorption spectroscopy (XAS) and electrochemical measurements revealed that the iron complex with N3-coordination is more effectively converted to Fe-N <subscript>4</subscript> sites catalyzing ORR with a TOF value of 0.21 e site <superscript>-1</superscript> s <superscript>-1</superscript> at 0.8 V vs. RHE. This indicates that the formation of Fe-N <subscript>4</subscript> sites is controlled by precise tuning of the chemical structure of the iron complex precursor.<br /> (© 2021 Wiley-VCH GmbH.)

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