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Issue 11, 2014
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Interface structure and reactivity of water-oxidation Ru–polyoxometalate catalysts on functionalized graphene electrodes

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Abstract

We combine classical empirical potentials and density functional theory (DFT) calculations to characterize the catalyst/electrode interface of a promising device for artificial photosynthesis. This system consists of inorganic Ru–polyoxometalate (Ru–POM) molecules that are supported by a graphitic substrate functionalized with organic dendrimers. The experimental atomic-scale characterization of the active interface under working conditions is hampered by the complexity of its structure, composition, as well as by the presence of the electrolyte or solvent. We provide a detailed atomistic model of the electrode/catalyst interface and show that the catalyst anchoring is remarkably dependent on water solvation. A tight host–guest binding geometry between the surface dendrimers and the Ru–POM catalyst is predicted under vacuum conditions. The solvent destabilizes this geometry, leads to unfolding of the dendrimers and to their flattening on the graphitic surface. The Ru–POM catalyst binds to this organic interlayer through a stable electrostatic link between one POM termination and the charged terminations of the dendrimers. The calculated dynamics and mobility of the Ru–POM catalyst at the electrode surface are in fair agreement with the available high-resolution transmission electron microscopy data. In addition, we demonstrate that the high thermodynamic water-oxidation efficiency of the Ru–POM catalyst is not affected by the binding to the electrode, thus rationalizing the similar electrochemical performances measured for homogeneous and heterogeneous Ru–POM catalysts.

Graphical abstract: Interface structure and reactivity of water-oxidation Ru–polyoxometalate catalysts on functionalized graphene electrodes

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The article was received on 22 Nov 2013, accepted on 16 Jan 2014 and first published on 16 Jan 2014


Article type: Paper
DOI: 10.1039/C3CP54943G
Author version available: Download Author version (PDF)
Citation: Phys. Chem. Chem. Phys., 2014,16, 5333-5341
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    Interface structure and reactivity of water-oxidation Ru–polyoxometalate catalysts on functionalized graphene electrodes

    C. Ma, S. Piccinin and S. Fabris, Phys. Chem. Chem. Phys., 2014, 16, 5333
    DOI: 10.1039/C3CP54943G

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