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Calcium Manganese Oxides as Oxygen Evolution Catalysts: O 2 Formation Pathways Indicated by 18 O‐Labelling Studies
Author(s) -
Shevela Dmitriy,
Koroidov Sergey,
Najafpour M. Mahdi,
Messinger Johannes,
Kurz Philipp
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201002548
Subject(s) - manganese , chemistry , catalysis , oxygen , hydrogen peroxide , photosystem ii , oxygen evolution , inorganic chemistry , oxygen evolving complex , photochemistry , photosynthesis , electrochemistry , organic chemistry , biochemistry , electrode
Oxygen evolution catalysed by calcium manganese and manganese‐only oxides was studied in 18 O‐enriched water. Using membrane‐inlet mass spectrometry, we monitored the formation of the different O 2 isotopologues 16 O 2 , 16 O 18 O and 18 O 2 in such reactions simultaneously with good time resolution. From the analysis of the data, we conclude that entirely different pathways of dioxygen formation catalysis exist for reactions involving hydrogen peroxide (H 2 O 2 ), hydrogen persulfate (HSO 5 − ) or single‐electron oxidants such as Ce IV and [Ru III (bipy) 3 ] 3+ . Like the studied oxide catalysts, the active sites of manganese catalase and the oxygen‐evolving complex (OEC) of photosystem II (PSII) consist of μ‐oxido manganese or μ‐oxido calcium manganese sites. The studied processes show very similar 18 O‐labelling behaviour to the natural enzymes and are therefore interesting model systems for in vivo oxygen formation by manganese metalloenzymes such as PSII.