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Issue 33, 2011
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Electrocatalytic oxygen evolution from water on a Mn(iiiv) dimer model catalyst—A DFT perspective

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Abstract

A complete water oxidation and oxygen evolution reaction (OER) cycle is monitored by means of density functional theory (DFT). A biomimetic model catalyst, comprising a μ-OH bridged Mn(IIIV) dimer truncated by acetylacetonate ligand analogs and hydroxides is employed. The reaction cycle is divided into four electrochemical hydrogen abstraction steps followed by a series of chemical steps. The former employ the tyrosine/tyrosyl redox couple acting as electron and proton sink, thus determining the reference potential. Stripping hydrogen from water leads to the formation of two highly unstable Mn(V)[double bond, length as m-dash]O/Mn(IV)–O˙ moieties, which subsequently combine to form a μ-peroxy O–O bond. O2 evolution results from subsequent consecutive replacement of the remaining Mn–O bonds by water. A Zener “spintronic” type mechanism for virtually barrierless O2 evolution is found. The applicability of DFT is discussed and extended to include the rate-limiting steps in the OER. Rather than attempting to compute transition states where KS-DFT is unreliable, an upper bound for the activation barrier of the O–O bond formation step is estimated from the hessians of the relevant intermediates.

Graphical abstract: Electrocatalytic oxygen evolution from water on a Mn(iii–v) dimer model catalyst—A DFT perspective

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Article information


Submitted
12 Oct 2010
Accepted
25 May 2011
First published
20 Jul 2011

Phys. Chem. Chem. Phys., 2011,13, 15069-15076
Article type
Paper

Electrocatalytic oxygen evolution from water on a Mn(IIIV) dimer model catalyst—A DFT perspective

M. Busch, E. Ahlberg and I. Panas, Phys. Chem. Chem. Phys., 2011, 13, 15069
DOI: 10.1039/C0CP02132F

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