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Highly Durable Oxygen Evolution Reaction Catalyst: Amorphous Oxyhydroxide Derived from Brownmillerite-Type Ca2FeCoO5

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Title: Highly Durable Oxygen Evolution Reaction Catalyst: Amorphous Oxyhydroxide Derived from Brownmillerite-Type Ca2FeCoO5
Authors: Sato, Yuki Browse this author
Aoki, Yoshitaka Browse this author →KAKEN DB
Takase, Kentaro Browse this author
Kiuchi, Hisao Browse this author
Kowalski, Damian Browse this author
Habazaki, Hiroki Browse this author →KAKEN DB
Keywords: OER
auger electron spectroscopy
extended X-ray absorption fine structure
Issue Date: 22-Jun-2020
Publisher: American Chemical Society
Journal Title: ACS applied energy materials
Volume: 3
Issue: 6
Start Page: 5269
End Page: 5276
Publisher DOI: 10.1021/acsaem.0c00159
Abstract: Brownmillerite-type Ca2FeCoO5 (CFCO) is a highly active electrocatalyst for the oxygen evolution reaction (OER). In this study, we identified the actual catalytically active phase of this oxide formed via the long-term OER and, moreover, demonstrated that the active phase can persist during the OER for 4 weeks without significant loss of electrocatalytic activity. The long-term durability tests were carried out on CFCO via continuous galvanostatic OER in 4 mol dm(-3) KOH aqueous solution for periods ranging from a few hours to 1 month, and the specimens submitted to the tests were characterized by means of electrochemical measurements and structural analysis using scanning electron microscopy, X-ray diffraction, transmission electron microscopy, Auger electron spectroscopy, and X-ray absorption fluorescence spectroscopy. CFCO was readily converted to amorphous cobalt oxyhydroxides with 10% Fe substituents through the OER process, and these compounds had a local rearrangement similar to that of the layered gamma-CoOOH-type structure. This transformation involved large morphological changes of the oxide particles because of the extensive dissolution of Ca and Fe, yielding skeletal grains made of oxyhydroxide nanosheet aggregates. The extended durability studies with total polarization charge density of the order of 10(5) C cm(-2) revealed that a (Co, Fe)OOH-like compound is the actual electrocatalytic phase.
Rights: This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS applied energy materials, copyright c American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see
Type: article (author version)
Appears in Collections:工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 幅崎 浩樹

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