Symes, M.D. , Surendranath, Y., Lutterman, D.A. and Nocera, D.G. (2011) Bidirectional and unidirectional PCET in a molecular model of a cobalt-based oxygen-evolving catalyst. Journal of the American Chemical Society, 133(14), pp. 5174-5177. (doi: 10.1021/ja110908v)
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Abstract
The oxidation of water to molecular oxygen is a kinetically demanding reaction that requires efficient coupling of proton and electron transfer. The key proton-coupled electron transfer (PCET) event in water oxidation mediated by a cobalt-phosphate-based heterogeneous catalyst is the one-electron, one-proton conversion of Co(III)-OH to Co(IV)-O. We now isolate the kinetics of this PCET step in a molecular Co(4)O(4) cubane model compound. Detailed electrochemical, stopped-flow, and NMR studies of the CoIII-OH to Co(IV)-O reaction reveal distinct mechanisms for the unidirectional PCET self-exchange reaction and the corresponding bidirectional PCET. A stepwise mechanism, with rate-limiting electron transfer is observed for the bidirectional PCET at an electrode surface and in solution, whereas a concerted proton electron transfer displaying a moderate KIE (4.3 +/- 0.2), is observed for the unidirectional self-exchange reaction.
Item Type: | Articles |
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Status: | Published |
Refereed: | Yes |
Glasgow Author(s) Enlighten ID: | Symes, Professor Mark |
Authors: | Symes, M.D., Surendranath, Y., Lutterman, D.A., and Nocera, D.G. |
Subjects: | Q Science > QD Chemistry |
College/School: | College of Science and Engineering > School of Chemistry |
Journal Name: | Journal of the American Chemical Society |
Publisher: | American Chemical Society |
ISSN: | 0002-7863 |
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