Adsorption-Induced Restructuring and Early Stages of Carbon-Nanotube Growth on Ni Nanoparticles

Authors

  • Dr. Yuexia Wang,

    1. Applied Ion Beam Physics Laboratory, Institute of Modern Physics, Fudan University, 200433 Shanghai (P. R. China)
    2. Physique des Solides Irradiés et des Nanostructures CP234, Faculté des Sciences, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Bruxelles (Belgium)
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  • Dr. Giovanni Barcaro,

    1. CNR-IPCF, Istituto per i Processi Chimico-Fisici del CNR, 56124 Pisa (Italy)
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  • Dr. Fabio R. Negreiros,

    1. CNR-IPCF, Istituto per i Processi Chimico-Fisici del CNR, 56124 Pisa (Italy)
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  • Dr. Thierry Visart de Bocarmé,

    1. Chimie Physique des Matériaux CP234, Faculté des Sciences, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Bruxelles (Belgium)
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  • Dr. Mathieu Moors,

    1. Chimie Physique des Matériaux CP234, Faculté des Sciences, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Bruxelles (Belgium)
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  • Dr. Norbert Kruse,

    1. Chimie Physique des Matériaux CP234, Faculté des Sciences, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Bruxelles (Belgium)
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  • Dr. Marc Hou,

    1. Physique des Solides Irradiés et des Nanostructures CP234, Faculté des Sciences, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Bruxelles (Belgium)
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  • Dr. Alessandro Fortunelli

    Corresponding author
    1. CNR-IPCF, Istituto per i Processi Chimico-Fisici del CNR, 56124 Pisa (Italy)
    • CNR-IPCF, Istituto per i Processi Chimico-Fisici del CNR, 56124 Pisa (Italy)
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Abstract

Carbon adsorption on various Ni surfaces is investigated as a function of coverage via a combination of first-principles simulations and field emission microscope experiments. It is found that carbon can be efficiently stored as subsurface carbides, but with different energetics on differently oriented surfaces depending on their compactness and density of adsorption sites. In the resulting morphological reshaping, {113} facets are predicted to grow at the expense of {111} and {100} facets, in excellent agreement with experimental observations. Moreover, at high coverage on the {113} surface the carbon adsorption energy passes through a maximum after which a structural crossover is realized such that carbon atoms tend to ascend to the surface to form one-dimensional chains (which are the precursors of graphitic nanostructures). This rationalizes the experimental observation of an incubation time between carbon storage and the beginning of catalytic growth, and provides insight into the early stages (nucleation mechanism) of carbon nanotubes on Ni nanoparticles.

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