Water Oxidation Catalysis by Co(II) Impurities in Co(III)4O4 Cubanes

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• 作者：Andrew M. Ullman ; Yi Liu ; Michael Huynh ; D. Kwabena Bediako ; Hongsen Wang ; Bryce L. Anderson ; David C. Powers ; John J. Breen ; H茅ctor D. Abru帽a ; Daniel G. Nocera
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：December 17, 2014
• 年：2014
• 卷：136
• 期：50
• 页码：17681-17688
• 全文大小：369K
• ISSN：1520-5126

文摘

The observed water oxidation activity of the compound class Co₄O₄(OAc)₄(Py鈥揦)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.