Mordkovich Vladimir Z, Karaeva Aida R, Kazennov Nikita V, Mitberg Eduard B, Nasraoui Mariem, Kulnitskiy Boris A, Blank Vladimir D
Technological Institute for Superhard and Novel Carbon Materials, 7A Tsentralnaya street, Troitsk, 108840 Moscow, Russia.
Department of Electrochemistry, Faculty of Chemistry, M.V. Lomonosov Moscow State University, Leninskie Gory 1/3, 119991 Moscow, Russia.
Materials (Basel). 2022 Oct 21;15(20):7377. doi: 10.3390/ma15207377.
Catalytic synthesis of carbon nanotubes (CNT) produces numerous various byproducts such as soot, graphite platelets, catalyst nanoparticles, etc. Identification of the byproduct formation mechanisms would help develop routes to more selective synthesis of better carbon-based materials. This work reports on the identification of the formation zone and conditions for rather unusual closed multishell carbon nanocapsules in a reactor for float-catalysis synthesis of longer CNT. Structural investigation of the formed nanocapsule material along with computational fluid dynamics (CFD) simulations of the reactor suggested a nanocapsule formation mechanism, in which CNT embryos are suppressed in growth by the in-reactor turbulence. By means of TEM and FFT investigation, it is found that differently oriented single crystals of γ-FeO, which do not have clear connections with each other, determine a spherical surface. The carbon atoms that seep through these joints do not form crystalline graphite layers. The resulting additional product in the form of graphene-coated (γ-Fe/FeC)/γ-FeO nanoparticles can be a lightweight and effective microwave absorber.
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