title: Striking influence of the catalyst support and its acid-base properties: new insight into the growth mechanism of carbon nanotubes.
abstract: In the accepted mechanisms of carbon nanotube (CNT) growth by catalytic chemical vapor deposition (CCVD), the catalyst support is falsely considered as a passive material whose only role is to prevent catalytic particles from coarsening. The chemical changes that occur to the carbon source molecules on the surface are mainly overlooked. Here, we demonstrate the strong influence of the support on the growth of CNTs and show that it can be tuned by controlling the acid-base character of the support surface. This finding largely clarifies the CCVD growth mechanism. The CNTs' growth stems from the support where the presence of basic sites catalyzes the aromatization and reduces the complexity of CNT precursor molecules. On basic supports, the growth is activated and CNTs are more than 1000 times longer than those produced on acidic supports. These results could be the bedrock of future development of more efficient growth of CNTs on surfaces of functional materials. Finally, the modification of the aciditiy of the catalyst support during the super growth process is also discussed.
authors.affiliation: Laboratory of Complex Matter Physics, Ecole Polytechnique Fédérale de Lausanne, Switzerland. arnaud.magrez@epfl.ch
authors.forename: Arnaud
authors.initials: A
authors.lastname: Magrez
authors.forename: Rita
authors.initials: R
authors.lastname: Smajda
authors.forename: Jin Won
authors.initials: JW
authors.lastname: Seo
authors.forename: Endre
authors.initials: E
authors.lastname: Horváth
authors.forename: Primoz Rebernik
authors.initials: PR
authors.lastname: Ribic
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Andresen
authors.forename: Donatello
authors.initials: D
authors.lastname: Acquaviva
authors.forename: Areta
authors.initials: A
authors.lastname: Olariu
authors.forename: Gábor
authors.initials: G
authors.lastname: Laurenczy
authors.forename: László
authors.initials: L
authors.lastname: Forró
mesh_terms: D000143:Acids / Q000737:chemistry*; D002384:Catalysis; D003460:Crystallization / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D000143:Acids; D046911:Macromolecular Substances; D037742:Nanotubes, Carbon