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

Rosalie Hocking, Robin Brimblecombe, Lan-Yun Chang, Archana Singh, Mun Hon Cheah, Chris Glover, William Casey, Leone Spiccia

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Abstract

Water oxidation in all oxygenic photosynthetic organisms is catalysed by the Mn(4)CaO(4) 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 Mn(2+).
Original languageEnglish
Pages (from-to)461 - 466
Number of pages6
JournalNature Chemistry
Volume3
Issue number6
DOIs
Publication statusPublished - 2011

Cite this

Hocking, R., Brimblecombe, R., Chang, L-Y., Singh, A., Cheah, M. H., Glover, C., Casey, W., & Spiccia, L. (2011). Water-oxidation catalysis by manganese in a geochemical-like cycle. Nature Chemistry, 3(6), 461 - 466. https://doi.org/10.1038/NCHEM.1049