Multiwalled carbon nanotubes were synthesized catalytically from ethylene in the presence of water vapor at transition metals of the iron subgroup. The structure of the obtained nanotubes was studied by transmission electron microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy. It was shown that the highest yields of carbon nanotubes with diameters between 20 and 40 nm, lengths of more than 1 µm, and average diameter of 0.92 nm for the innermost tube were obtained at a nickel catalyst with a water vapor concentration of 0.32%.

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A. I. Tripol'skii, T. G. Serebrii, N. V. Lemesh, V. A. Khavrus', T. S. Ivashchenko, and P. E. Strizhak Fractal geometry was used to describe the morphology of agglomerates of carbon nanotubes (CNT) obtained by the thermal decomposition of ethylene in the presence of water vapor over nickel nanoparticles. Analysis of the structure of the CNT by electron transmission and scanning microscopy showed that CNT agglomerates have fractal structure with fractal dimension D 0 = 2.65±0.05 and their formation proceeds by the same mechanism regardless of the ethylene partial pressure.