A Model for the Activation of Metallic Catalysts for Multi-Walled Carbon Nanotube Growth
Catalyst Design: 4th International School-Conference on Catalysis for Young Scientists
05-06 Sep 2015
|| Krasnikov Dmitry Vicktorovich
, Kuznetsov Vladimir Lʹvovich
, Shmakov Alexander Nikolaevich
, Selyutin Aleksandr
, Ishchenko Arcady Vladimirovich
Boreskov Institute of Catalysis SB RAS
Novosibirsk State University
National Research Tomsk State University
Due to their unique mechanical, optical properties, high electrical and thermal conductivity multi-walled carbon nanotubes (MWCNTs) are of great interest to be applied in such industries as aerospace, constructions, electronics, medicine etc. Extensive attention to MWCNTs in past two decades has allowed developing of the techniques for nanotube largescale production, for tunable surface functionalization, quality characterization. However, an amount MWCNT-based aplications is still limited. This can be attributed to lack in understanding mechanism and processes to take place during MWCNT growth. Therefore, one fails to fully conrol tailor characterstics of MWCNTs. Such properties of carbon nanotubes as diameter distribution, number and structure of walls, and morphology are determined during the activation of the MWCNT grwoth catalyst.
In the present work, a kinetic aspects of the catalyst activation have been studied using in situ [1-3] and ex situ methods (fig. 1). Special attention have been paid to mechanism of the activation of the MWCNT growth catalyst. At least for elementary steps during the activation have been distinguished. There are reduction of the active metals, their sintering accompanied with saturation with carbon with the following nucleation of carbon nanotube . It was found that sintering of the metallic particles is the rate-determining step of the catalyst activation. On the basis of this mechanism a kinetic model for the activation has been developed. The results obtained with this model are in good agreement with expreiment.