Water-oxidation catalysis by manganese in a geochemical-like cycle

Hocking, Rosalie K., Brimblecombe, Robin, Chang, Lan-Yun, Singh, Archana, Cheah, Mun Hon, Glover, Chris, Casey, William H., and Spiccia, Leone (2011) Water-oxidation catalysis by manganese in a geochemical-like cycle. Nature Chemistry, 3 (6). pp. 461-466.

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Water oxidation in all oxygenic photosynthetic organisms is catalysed by the Mn₄CaO₄ cluster of Photosystem II. This cluster has inspired the development of synthetic manganese catalysts for solar energy production. A photoelectrochemical device, made by impregnating a synthetic tetranuclear-manganese cluster into a Nafion matrix, has been shown to achieve efficient water oxidation catalysis. We report here in situ X-ray absorption spectroscopy and transmission electron microscopy studies that demonstrate that this cluster dissociates into Mn(II) compounds in the Nafion, which are then reoxidized to form dispersed nanoparticles of a disordered Mn(III/IV)-oxide phase. Cycling between the photoreduced product and this mineral-like solid is responsible for the observed photochemical water-oxidation catalysis. The original manganese cluster serves only as a precursor to the catalytically active material. The behaviour of Mn in Nafion therefore parallels its broader biogeochemistry, which is also dominated by cycles of oxidation into solid Mn(III/IV) oxides followed by photoreduction to Mn²⁺.

Item ID: 28906
Item Type: Article (Research - C1)
ISSN: 1755-4349
Date Deposited: 21 Aug 2013 09:22
FoR Codes: 03 CHEMICAL SCIENCES > 0302 Inorganic Chemistry > 030201 Bioinorganic Chemistry @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970103 Expanding Knowledge in the Chemical Sciences @ 100%
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