In-situ Spectroscopy of Water Oxidation at Ir Oxide Nanocluster Drivenby Visible TiOCr Charge-Transfer Chromophore in Mesoporous Silica

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An all-inorganic photocatalytic unit consisting of a binuclear TiOCr charge-transfer chromophore coupled to an Ir oxide nanocluster has been assembled on the pore surface of mesoporous silica AlMCM-41. In situ FT-Raman and EPR spectroscopy of an aqueous suspension of the resulting IrxOy-TiCr-AlMCM-41 powder reveal the formation of superoxide species when exciting the Ti(IV)OCr(III) --> Ti(III)OCr(IV) metal-to-metal charge-transfer chromophore with visible light. Use of H218O confirms that the superoxide species originates from oxidation of water. Photolysis in the absence of persulfate acceptor leads to accumulation of Ti(III) instead. The results are explained by photocatalytic oxidation of water at Ir oxide nanoclusters ... continued below

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Frei, Heinz; Han, Hongxian & Frei, Heinz June 3, 2008.

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An all-inorganic photocatalytic unit consisting of a binuclear TiOCr charge-transfer chromophore coupled to an Ir oxide nanocluster has been assembled on the pore surface of mesoporous silica AlMCM-41. In situ FT-Raman and EPR spectroscopy of an aqueous suspension of the resulting IrxOy-TiCr-AlMCM-41 powder reveal the formation of superoxide species when exciting the Ti(IV)OCr(III) --> Ti(III)OCr(IV) metal-to-metal charge-transfer chromophore with visible light. Use of H218O confirms that the superoxide species originates from oxidation of water. Photolysis in the absence of persulfate acceptor leads to accumulation of Ti(III) instead. The results are explained by photocatalytic oxidation of water at Ir oxide nanoclusters followed by trapping of the evolving O2 by transient Ti(III) centers to yield superoxide. Given the flexibility to select donor metals with appropriate redox potential, photocatalytic units consisting of a binuclear charge-transfer chromophore coupled to a water oxidation catalyst shown here constitute a step towards thermodynamically efficient visible light water oxidation units.

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  • Journal Name: Journal of Physical Chemistry C

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  • Report No.: LBNL-324E
  • Grant Number: DE-AC02-05CH11231
  • Office of Scientific & Technical Information Report Number: 929434
  • Archival Resource Key: ark:/67531/metadc899963

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  • June 3, 2008

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  • Sept. 27, 2016, 1:39 a.m.

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  • Oct. 3, 2016, 1:47 p.m.

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Frei, Heinz; Han, Hongxian & Frei, Heinz. In-situ Spectroscopy of Water Oxidation at Ir Oxide Nanocluster Drivenby Visible TiOCr Charge-Transfer Chromophore in Mesoporous Silica, article, June 3, 2008; Berkeley, California. (digital.library.unt.edu/ark:/67531/metadc899963/: accessed June 21, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.