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A Computational Study of the Mechanism of Hydrogen Evolution by Cobalt(Diimine-Dioxime) Catalysts

Authors

  • Dr. Anirban Bhattacharjee,

    1. Dynamo Team, DYNAMOP Group, UMR 5075, Université Grenoble 1, CNRS, CEA, Institut de Biologie Structurale “Jean-Pierre Ebel”, 41 rue Jules Horowitz, 38027 Grenoble Cedex 1 (France)
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  • Dr. Eugen S. Andreiadis,

    1. Laboratoire de Chimie et Biologie des Métaux, UMR 5249, Université Grenoble 1, CNRS, CEA, 17 rue des Martyrs 38054 Grenoble Cedex 9 (France)
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  • Dr. Murielle Chavarot-Kerlidou,

    1. Laboratoire de Chimie et Biologie des Métaux, UMR 5249, Université Grenoble 1, CNRS, CEA, 17 rue des Martyrs 38054 Grenoble Cedex 9 (France)
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  • Prof. Marc Fontecave,

    1. Laboratoire de Chimie et Biologie des Métaux, UMR 5249, Université Grenoble 1, CNRS, CEA, 17 rue des Martyrs 38054 Grenoble Cedex 9 (France)
    2. Collège de France, 11 place Marcellin-Berthelot, 75005 Paris (France)
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  • Dr. Martin J. Field,

    Corresponding author
    1. Dynamo Team, DYNAMOP Group, UMR 5075, Université Grenoble 1, CNRS, CEA, Institut de Biologie Structurale “Jean-Pierre Ebel”, 41 rue Jules Horowitz, 38027 Grenoble Cedex 1 (France)
    • Martin J. Field, Dynamo Team, DYNAMOP Group, UMR 5075, Université Grenoble 1, CNRS, CEA, Institut de Biologie Structurale “Jean-Pierre Ebel”, 41 rue Jules Horowitz, 38027 Grenoble Cedex 1 (France)

      Vincent Artero, Laboratoire de Chimie et Biologie des Métaux, UMR 5249, Université Grenoble 1, CNRS, CEA, 17 rue des Martyrs 38054 Grenoble Cedex 9 (France)

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  • Dr. Vincent Artero

    Corresponding author
    1. Laboratoire de Chimie et Biologie des Métaux, UMR 5249, Université Grenoble 1, CNRS, CEA, 17 rue des Martyrs 38054 Grenoble Cedex 9 (France)
    • Martin J. Field, Dynamo Team, DYNAMOP Group, UMR 5075, Université Grenoble 1, CNRS, CEA, Institut de Biologie Structurale “Jean-Pierre Ebel”, 41 rue Jules Horowitz, 38027 Grenoble Cedex 1 (France)

      Vincent Artero, Laboratoire de Chimie et Biologie des Métaux, UMR 5249, Université Grenoble 1, CNRS, CEA, 17 rue des Martyrs 38054 Grenoble Cedex 9 (France)

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Abstract

Cobalt(diimine-dioxime) complexes catalyze hydrogen evolution with low overpotentials and remarkable stability. In this study, DFT calculations were used to investigate their catalytic mechanism, to demonstrate that the initial active state was a CoI complex and that H2 was evolved in a heterolytic manner through the protonation of a CoII[BOND]hydride intermediate. In addition, these catalysts were shown to adjust their electrocatalytic potential for hydrogen evolution to the pH value of the solution and such a property was assigned to the presence of a H+-exchange site on the oxime bridge. It was possible to establish that protonation of the bridge was directly involved in the H2-evolution mechanism through proton-coupled electron-transfer steps. A consistent mechanistic scheme is proposed that fits the experimentally determined electrocatalytic and electrochemical potentials of cobalt(diimine-dioxime) complexes and reproduces the observed positive shift of the electrocatalytic potential with increasing acidity of the proton source.

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