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High Turnover in a Photocatalytic System for Water Reduction to Produce Hydrogen Using a Ru, Rh, Ru Photoinitiated Electron Collector

Authors

  • Dr. Shamindri M. Arachchige,

    1. Department of Chemistry, Virginia Polytechnic Institute and State University, 107 Davidson Hall, Blacksburg, VA 24060-0212 (USA), Fax: (+1) 540 231 3255
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  • Ryan Shaw,

    1. Department of Chemistry, Virginia Polytechnic Institute and State University, 107 Davidson Hall, Blacksburg, VA 24060-0212 (USA), Fax: (+1) 540 231 3255
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  • Travis A. White,

    1. Department of Chemistry, Virginia Polytechnic Institute and State University, 107 Davidson Hall, Blacksburg, VA 24060-0212 (USA), Fax: (+1) 540 231 3255
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  • Vimal Shenoy,

    1. Department of Chemistry, Virginia Polytechnic Institute and State University, 107 Davidson Hall, Blacksburg, VA 24060-0212 (USA), Fax: (+1) 540 231 3255
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  • Hei-Man Tsui,

    1. Department of Chemistry, Virginia Polytechnic Institute and State University, 107 Davidson Hall, Blacksburg, VA 24060-0212 (USA), Fax: (+1) 540 231 3255
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  • Prof. Karen J. Brewer

    Corresponding author
    1. Department of Chemistry, Virginia Polytechnic Institute and State University, 107 Davidson Hall, Blacksburg, VA 24060-0212 (USA), Fax: (+1) 540 231 3255
    • Department of Chemistry, Virginia Polytechnic Institute and State University, 107 Davidson Hall, Blacksburg, VA 24060-0212 (USA), Fax: (+1) 540 231 3255
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Abstract

Covalent coupling of RuII light absorbers to a RhIII electron collecting site through polyazine bridging ligands affords photocatalytic production of H2 in the presence of visible light and a sacrificial electron donor. A robust photocatalytic system displaying a high turnover of the photocatalyst has been developed using the photoinitiated electron collector [{(bpy)2Ru(dpp)}2RhBr2]5+ (bpy=2,2’-bipyridine; dpp=2,3-bis(2-pyridyl)pyrazine) and N,N-dimethylaniline in DMF/H2O. Studies have shown that increased [DMA], the headspace volume, and the use of DMF solvent improves the systems performance and stability providing mechanistic insight into the deactivation routes of the photocatalytic system. Photolysis of the system at 460 nm generates 20 mL of H2 in 19.5 h with a maximum Φ=0.023 based on H2 produced and an overall Φ=0.014 and 280 turnovers of the photocatalyst. The photocatalytic system also displays long-term photostability with 30 mL of H2 generated and 420 turnovers in 50 h under the same conditions. Prolonged photolysis provides 820 mol H2 per mole of catalyst.

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