Authors: Justyna Majewska Beata Michalkiewicz
Publish Date: 2013/04/18
Volume: 111, Issue: 4, Pages: 1013-1016
Abstract
The onestep method of carbon nanotubes filled with continuous cobalt nanowires CoFCNT synthesis is presented Co/ZSM5 8 wt Co was used as catalyst for CoFCNT production by methane decomposition at the temperature of 400 °C and 800 °C at atmospheric pressure in a conventional gasflow system The average diameter of the CoFCNT is about 25 and 40 nm for products obtained at 400 °C and at 800 °C respectively The average size of coherently scattering domains along the normal to graphite layers L c the interlayer spacing d 002 the graphitization degree of carbon and the relative intensities of the G and D bands in Raman spectroscopy were determined to characterize the quality of carbon It was proved that cobaltfilled carbon nanotubes can be produced by a simple method The results of XRD FESEM and TEM show that CoFCNT can be obtained even at 400 °C by catalytic decomposition of methane On the basis of XRD TEM Raman spectroscopy was found that at a temperature of 800 °C a better quality of carbon was producedThe initial studies on carbon nanotubes CNTs filled with metals were carried out in 1993 by Iijima 1 which demonstrated the successful encapsulation of Pb In the following years increasing effort was directed to the preparation of CNTs as template nanowiresIn order for metal filled CNT synthesis several methods have been attempted The CNT can be filled by a physical or chemical method 2 In the physical method the nanotubes are filled with melted metal due to the capillarity effect 3 4 In the chemical method the nanotubes are opened by boiling acid then the inclusion of metal oxide or metal is carried out Onestep methods of metal filled CNT preparation are known as well Mainly an arc discharge technique was applied 3 4 but it requires high temperaturesBlank et al 7 described cobaltfilled nanotube synthesis obtained from CO over Co/Yzeolite catalysts Despite the applied high temperature 720 °C and pressure 005 GPa that was applied TEM analysis showed the presence of some cobalt particles inside the carbon nanotubes Long cobalt nanowires were not observedSome authors reported on methane to carbon nanotubes or nanoparticles decomposition over cobalt contained catalysts 8 9 but to the best of our knowledge there is no information on nanotubes filled with continuous cobalt nanowires prepared from methaneThe choice of cobalt as the material encapsulated inside carbon nanotubes CNTs is motivated by the interesting magnetic properties of composite cobalt–carbon nanomaterials which are of great interest for various applications such as magnetic data storage ferrofluids or magnetic resonance imaging 10In this paper we show that the Co/ZSM5 prepared by the impregnation method can be used as catalysts of CNT filled with continuous cobalt nanowires CoFCNT growth from methane decomposition even at the temperature of 400 °C This is the onestep method that is simpler and cheaper than the others described up to now
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