Abstract |
Manganese oxides (MnOx ) are considered to be promising catalysts for water oxidation. Building on our previous studies showing that the catalytic activity of MnOx films electrodeposited from aqueous electrolytes is improved by a simple heat treatment, we have explored the origin of the catalytic enhancement at an electronic level by X-ray absorption spectroscopy (XAS). The Mn L-edge XA spectra measured at various heating stages were fitted by linear combinations of the spectra of the well-defined manganese oxides-MnO, Mn3 O4 , Mn2 O3 , MnO2 and birnessite. This analysis identified two major manganese oxides, Mn3 O4 and birnessite, that constitute 97 % of the MnOx films. Moreover, the catalytic improvement on heat treatment at 90 °C is related to the conversion of a small amount of birnessite to the Mn3 O4 phase, accompanied by an irreversible dehydration process. Further dehydration at higher temperature (120 °C), however, leads to a poorer catalytic performance.
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Authors | Munirah Khan, Jie Xiao, Fengling Zhou, Mikhail Yablonskikh, Douglas R MacFarlane, Leone Spiccia, Emad F Aziz |
Journal | ChemSusChem
(ChemSusChem)
Vol. 8
Issue 11
Pg. 1980-5
(Jun 08 2015)
ISSN: 1864-564X [Electronic] Germany |
PMID | 25940315
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Copyright | © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. |
Chemical References |
- Manganese Compounds
- Oxides
- Water
- manganese oxide
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Topics |
- Catalysis
- Electrochemistry
- Hot Temperature
- Manganese Compounds
(chemistry)
- Oxidation-Reduction
- Oxides
(chemistry)
- Water
(chemistry)
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