CCVD synthesis of carbon nanotubes from (Mg,Co,Mo)O catalysts: influence of the proportions of cobalt and molybdenum

Emmanuel Flahaut (1) , Alain Peigney (1) , Wolfgang Bacsa (1) , Revathi Bacsa (1) , Christophe Laurent (1)

1 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux

Carbon nanotubes have been synthesised by catalytic chemical vapour deposition of a H2-CH4 mixture (18 mol% CH4) over (Mg,Co,Mo)O catalysts. The total amount of cobalt and molybdenum has been kept constant at 1 cat% and the proportion of molybdenum with respect to cobalt has been varied from x(Mo) = 0.25-1.0. This variation has important effects on both the yield and the nature (number of walls, straight walls or bamboo-like structures) of the carbon nanotubes. It also has an influence on the purity of the samples (amount of encapsulated metal particles, presence or not of amorphous carbon deposits). For x = 0.25, the nanotubes were mainly double- and triple-walled (inner diameter less than 3 nm); samples prepared from catalysts with higher molybdenum ratios contained larger multi-walled carbon nanotubes (inner diameter up to 9 nm), having up to 13 concentric walls. It is proposed that different growth mechanisms may occur depending on the initial composition of the catalyst.

Mots clés: CCVD; Single wall; Double wall; Carbon nanotubes

Domaines: Matériaux; Matériaux

Emmanuel Flahaut, Alain Peigney, Wolfgang Bacsa, Revathi Bacsa, Christophe Laurent. CCVD synthesis of carbon nanotubes from (Mg,Co,Mo)O catalysts: influence of the proportions of cobalt and molybdenum. Journal of Materials Chemistry, 2004, vol. 14, pp. 646-653. ⟨10.1039/b312367g⟩. ⟨hal-00917603⟩