title: Adsorption-induced restructuring and early stages of carbon-nanotube growth on Ni nanoparticles.
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.
authors.affiliation: Applied Ion Beam Physics Laboratory, Institute of Modern Physics, Fudan University, 200433 Shanghai, PR China.
authors.forename: Yuexia
authors.initials: Y
authors.lastname: Wang
authors.forename: Giovanni
authors.initials: G
authors.lastname: Barcaro
authors.forename: Fabio R
authors.initials: FR
authors.lastname: Negreiros
authors.forename: Thierry
authors.initials: T
authors.lastname: Visart de Bocarmé
authors.forename: Mathieu
authors.initials: M
authors.lastname: Moors
authors.forename: Norbert
authors.initials: N
authors.lastname: Kruse
authors.forename: Marc
authors.initials: M
authors.lastname: Hou
authors.forename: Alessandro
authors.initials: A
authors.lastname: Fortunelli
mesh_terms: D000327:Adsorption; D053768:Metal Nanoparticles / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D037742:Nanotubes, Carbon; D009532:Nickel