The Structure and Transport Properties of Single-walled Carbon Nanotubes Modified by Cobalt-containing Complexes

Authors I.V. Ovsiienko1 , T.A. Len1 , L.Yu. Matzui1 , O.A. Golub2, Yu. I. Prylutskyy1, T. L. Tsaregradskaya1, G.V. Saenko1

1Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska St., 01601 Kyiv, Ukraine

2National University “Kyiv-Mohyla Academy”, 2, G. Skovoroda St., 04070 Kyiv, Ukraine

Issue Volume 12, Year 2020, Number 6
Dates Received 28 August 2020; revised manuscript received 20 December 2020; published online 25 December 2020
Citation I.V. Ovsiienko, T.A. Len, L.Yu. Matzui, et al., J. Nano- Electron. Phys. 12 No 6, 06023 (2020)
PACS Number(s) 61.48.De, 88.30.rh
Keywords Single-walled carbon nanotubes, Cobalt-containing complexes, Magnetic susceptibility, Hopping conductivity with the variable hopping length.

The paper presents the results of investigation of structural and morphological peculiarities and transport properties of single-walled carbon nanotubes modified by cobalt-containing complexes. A scheme that allows simultaneously to clean the source nanocarbon material from the catalyst impurities and particles of disordered carbon, to separate single-walled tubes bunches into individual tubes, to cut the tubes along to defects and to modify tubes surface by cobalt-containing complexes is proposed. Using the thermomagnetometric method, it was found that attached to the surface of the carbon nanotubes cobalt is in the form of cations in the complicated complexes. When heating modified carbon nanotubes the complicated complexes are destroyed, and cobalt nanoparticles are formed. It is revealed that for bulk specimens of source single-walled carbon nanotubes the main mechanism of conductivity is the hopping conductivity with the variable hopping length for 3D system. Such conduction mechanism is typical of disordered graphite materials, as well as of mats and binders of single-walled carbon nanotubes. It is shown that modification of single-walled carbon nanotubes by cobalt-containing complexes results in a change in the character of the conductivity for bulk specimens of single-walled carbon nanotubes. For bulk specimens of modified single-walled carbon nanotubes, conductivity is described in terms of power temperature law that is typical of individual single-walled carbon nanotubes. It is shown that such a change in the conduction mechanism during surface modification is associated with the creation of a small negative charge on the surface of nanotubes during the modification.

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