Ullman Andrew M, Liu Yi, Huynh Michael, Bediako D Kwabena, Wang Hongsen, Anderson Bryce L, Powers David C, Breen John J, Abruña Héctor D, Nocera Daniel G
Department of Chemistry and Chemical Biology, Harvard University , 12 Oxford Street, Cambridge, Massachusetts 02138, United States.
J Am Chem Soc. 2014 Dec 17;136(50):17681-8. doi: 10.1021/ja5110393. Epub 2014 Dec 4.
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.
化合物Co4O4(OAc)4(Py-X)4所观察到的水氧化活性源自Co(II)杂质。该杂质被氧化生成著名的Co-OEC多相钴酸盐催化剂，它是一种活性水氧化催化剂。我们展示了电子顺磁共振光谱、核磁共振线宽分析和电化学滴定的结果，以确定Co(II)杂质的存在，它是已报道的Co4O4分子立方烷水氧化活性的主要来源。差分电化学质谱用于表征玻璃碳在水氧化电位下的变化情况，并表明在水氧化催化研究中应谨慎使用此类电极材料。
