Water Oxidation Catalysis by Co(II) Impurities in Co(III)4O4 Cubanes
نویسندگان
چکیده
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.
منابع مشابه
Synthetic control and empirical prediction of redox potentials for Co4O4 cubanes over a 1.4 V range: implications for catalyst design and evaluation of high-valent intermediates in water oxidation† †Electronic supplementary information (ESI) available. CCDC 1532026–1532032. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc00627f Click here for additional data file. Click here for additional data file.
The oxo-cobalt cubane unit [Co4O4] is of interest as a homogeneous oxygen-evolution reaction (OER) catalyst, and as a functional mimic of heterogeneous cobalt oxide OER catalysts. The synthesis of several new cubanes allows evaluation of redox potentials for the [Co4O4] cluster, which are highly sensitive to the ligand environment and span a remarkable range of 1.42 V. The [Co 4O4] /[Co 3 Co O4...
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