Bidirectional and unidirectional PCET in a molecular model of a cobalt-based oxygen-evolving catalyst

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)

Full text not currently available from Enlighten.

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
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Symes, Dr 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

University Staff: Request a correction | Enlighten Editors: Update this record