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Title	en Highly Durable Oxygen Evolution Reaction Catalyst: Amorphous Oxyhydroxide Derived from Brownmillerite-Type Ca2FeCoO5
Creator	en Sato, Yuki en Aoki, Yoshitaka NRID 1000050360475 en Takase, Kentaro en Kiuchi, Hisao en Kowalski, Damian en Habazaki, Hiroki NRID 1000050208568
Accessrights	open access
Rights	en 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 https://pubs.acs.org/doi/10.1021/acsaem.0c00159.
Subject	Other en OER Other en brownmillerite Other en Ca2FeCoO5 Other en electrocatalyst Other en auger electron spectroscopy Other en extended X-ray absorption fine structure
Description	Abstract en 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.
Publisher	en American Chemical Society
Date	Issued2020-06-22
Language	eng
Resource Type	journal article
Version Type	AM
Identifier	HDL http://hdl.handle.net/2115/81967
Relation	isVersionOf DOI https://doi.org/10.1021/acsaem.0c00159
Journal	PISSN 2574-0962 en ACS applied energy materials Volume Number3 Issue Number6 Page Start5269 Page End5276
File	fulltext manuscript_black.pdf 2.17 MB (application/pdf) Issued2020-06-22
Oaidate	2023-07-26