About the step-flow mechanism at the origin of graphene crystallisation at the surface of catalysts - École polytechnique Access content directly
Preprints, Working Papers, ... Year : 2013

About the step-flow mechanism at the origin of graphene crystallisation at the surface of catalysts

Abstract

The nucleation and growth of multiwall carbon nanotubes (MWCNTs) at the surface of crystalline iron-based catalysts are studied by in situ annealing and high-resolution transmission electron microscopy. Graphene planes, parallel to the catalyst surface, appear by a mechanism of step flow, where the atomic layers of catalyst are "replaced" by graphene layers. More interestingly, as the catalyst particles have curved or poly-faceted surfaces, those catalyst atomic layers correspond to no definite atomic plane. The step height may thus vary along a given step flow process. Step bunching due to impeded step migration, in certain growth conditions, yields characteristic catalyst nail-head shapes. Mastering this mechanism opens up the way to tailor the structure of MWCNTs, e.g. with highly parallel carbon walls.
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Dates and versions

hal-00880670 , version 1 (08-11-2013)

Identifiers

  • HAL Id : hal-00880670 , version 1

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Jean-Luc Maurice, Didier Pribat, Zhanbing He, Gilles Patriarche, Costel Sorin Cojocaru. About the step-flow mechanism at the origin of graphene crystallisation at the surface of catalysts. 2013. ⟨hal-00880670⟩
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