Water oxidation catalysis by Co(II) impurities in Co(III)4O4 cubanes

Andrew M. Ullman; Yi Liu; Michael Huynh; D. Kwabena Bediako; Hongsen Wang; Bryce L. Anderson; David C. Powers; John J. Breen; Héctor D. Abruña; Daniel G. Nocera

doi:10.1021/ja5110393

Water oxidation catalysis by Co(II) impurities in Co(III)₄O₄ cubanes

Andrew M. Ullman, Yi Liu, Michael Huynh, D. Kwabena Bediako, Hongsen Wang, Bryce L. Anderson, David C. Powers, John J. Breen, Héctor D. Abruña, Daniel G. Nocera

Research output: Contribution to journal › Article › peer-review

154 Scopus citations

Abstract

The observed water oxidation activity of the compound class Co₄O₄(OAc)₄(Py-X)₄ emanates from a Co(II) impurity. This impurity is oxidized to produce the well-known Co-OEC heterogeneous cobaltate catalyst, which is an active water oxidation catalyst. We present results from electron paramagnetic resonance spectroscopy, nuclear magnetic resonance line broadening analysis, and electrochemical titrations to establish the existence of the Co(II) impurity as the major source of water oxidation activity that has been reported for Co₄O₄ molecular cubanes. Differential electrochemical mass spectrometry is used to characterize the fate of glassy carbon at water oxidizing potentials and demonstrate that such electrode materials should be used with caution for the study of water oxidation catalysis.

Original language	English
Pages (from-to)	17681-17688
Number of pages	8
Journal	Journal of the American Chemical Society
Volume	136
Issue number	50
DOIs	https://doi.org/10.1021/ja5110393
State	Published - Dec 17 2014
Externally published	Yes

Funding

Funders	Funder number
National Institutes of Health	EB-002026, P41 EB-002804
National Stroke Foundation	ECS-0335765, CHE-1346572
U.S. Department of Energy	DE-AC02-06CH11357
National Institute of Biomedical Imaging and Bioengineering	R01EB002804
National Institute of Biomedical Imaging and Bioengineering

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title = "Water oxidation catalysis by Co(II) impurities in Co(III)4O4 cubanes",

abstract = "The observed water oxidation activity of the compound class Co4O4(OAc)4(Py-X)4 emanates from a Co(II) impurity. This impurity is oxidized to produce the well-known Co-OEC heterogeneous cobaltate catalyst, which is an active water oxidation catalyst. We present results from electron paramagnetic resonance spectroscopy, nuclear magnetic resonance line broadening analysis, and electrochemical titrations to establish the existence of the Co(II) impurity as the major source of water oxidation activity that has been reported for Co4O4 molecular cubanes. Differential electrochemical mass spectrometry is used to characterize the fate of glassy carbon at water oxidizing potentials and demonstrate that such electrode materials should be used with caution for the study of water oxidation catalysis.",

author = "Ullman, {Andrew M.} and Yi Liu and Michael Huynh and Bediako, {D. Kwabena} and Hongsen Wang and Anderson, {Bryce L.} and Powers, {David C.} and Breen, {John J.} and Abru{\~n}a, {H{\'e}ctor D.} and Nocera, {Daniel G.}",

note = "Publisher Copyright: {\textcopyright} 2014 American Chemical Society.",

year = "2014",

month = dec,

day = "17",

doi = "10.1021/ja5110393",

language = "English",

volume = "136",

pages = "17681--17688",

journal = "Journal of the American Chemical Society",

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TY - JOUR

T1 - Water oxidation catalysis by Co(II) impurities in Co(III)4O4 cubanes

AU - Ullman, Andrew M.

AU - Liu, Yi

AU - Huynh, Michael

AU - Bediako, D. Kwabena

AU - Wang, Hongsen

AU - Anderson, Bryce L.

AU - Powers, David C.

AU - Breen, John J.

AU - Abruña, Héctor D.

AU - Nocera, Daniel G.

PY - 2014/12/17

Y1 - 2014/12/17

N2 - The observed water oxidation activity of the compound class Co4O4(OAc)4(Py-X)4 emanates from a Co(II) impurity. This impurity is oxidized to produce the well-known Co-OEC heterogeneous cobaltate catalyst, which is an active water oxidation catalyst. We present results from electron paramagnetic resonance spectroscopy, nuclear magnetic resonance line broadening analysis, and electrochemical titrations to establish the existence of the Co(II) impurity as the major source of water oxidation activity that has been reported for Co4O4 molecular cubanes. Differential electrochemical mass spectrometry is used to characterize the fate of glassy carbon at water oxidizing potentials and demonstrate that such electrode materials should be used with caution for the study of water oxidation catalysis.

AB - The observed water oxidation activity of the compound class Co4O4(OAc)4(Py-X)4 emanates from a Co(II) impurity. This impurity is oxidized to produce the well-known Co-OEC heterogeneous cobaltate catalyst, which is an active water oxidation catalyst. We present results from electron paramagnetic resonance spectroscopy, nuclear magnetic resonance line broadening analysis, and electrochemical titrations to establish the existence of the Co(II) impurity as the major source of water oxidation activity that has been reported for Co4O4 molecular cubanes. Differential electrochemical mass spectrometry is used to characterize the fate of glassy carbon at water oxidizing potentials and demonstrate that such electrode materials should be used with caution for the study of water oxidation catalysis.

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EP - 17688

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

IS - 50

ER -

Water oxidation catalysis by Co(II) impurities in Co(III)₄O₄ cubanes

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