Issue 33, 2011

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

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

Supplementary files

Article information

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

Phys. Chem. Chem. Phys., 2011,13, 15069-15076

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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