EPR Evidence for Co(IV) Species Produced During Water Oxidation at Neutral pH

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• 作者：J. Gregory McAlpin ; Yogesh Surendranath ; Mircea Dinc ; Troy A. Stich ; Sebastian A. Stoian ; William H. Casey ; Daniel G. Nocera ; R. David Britt
• 刊名：Journal of the American Chemical Society
• 出版年：2010
• 出版时间：May 26, 2010
• 年：2010
• 卷：132
• 期：20
• 页码：6882-6883
• 全文大小：117K
• 年卷期：v.132,no.20(May 26, 2010)
• ISSN：1520-5126

文摘

Thin-film water oxidation catalysts (Co−Pi) prepared by electrodeposition from phosphate electrolyte and Co(NO₃)₂ have been characterized by electron paramagnetic resonance (EPR) spectroscopy. Co−Pi catalyst films exhibit EPR signals corresponding to populations of both Co(II) and Co(IV). As the deposition voltage is increased into the region where water oxidation prevails, the population of Co(IV) rises and the population of Co(II) decreases. The changes in the redox speciation of the film can also be induced, in part, by prolonged water oxidation catalysis in the absence of additional catalyst deposition. These results provide spectroscopic evidence for the formation of Co(IV) species during water oxidation catalysis at neutral pH.