Direct synthesis of carbon nanotubes decorated with size-controllable Fe nanoparticles encapsulated by graphitic layers

Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, PR China
Carbon (Impact Factor: 6.2). 09/2008; 46(11):1417-1423. DOI: 10.1016/j.carbon.2008.06.021
Source: OAI


A simple method has been developed for direct synthesis of magnetic multi-walled carbon nanotubes (MWCNTs) homogeneously decorated with size-controllable Fe nanoparticles (Fe-NPs) encapsulated by graphitic layers on the MWCNT surface by pyrolysis of ferrocene. These composites have similar C/Fe atomic ratio of ∼10 and exhibit sufficiently high saturation magnetization for magnetic separation in a liquid phase. Moreover, with 0, ∼1, ∼2 wt% sulfur as growth promoter, the size of Fe-NPs can be controlled with an average diameter of ∼5, ∼22 and ∼42 nm, respectively. When compared to time-consuming wet-chemical methods, the simplicity of this method should allow easy large-scale production of these magnetically functionalized MWCNTs, which can be used as catalyst supports with high stability for effective magnetic separation in liquid-phase reactions, especially under acid/basic conditions.

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    • "The addition of negligible amounts of CNTs to metallic and metallic oxide nanofluids opens new ways of obtaining versatile performance characteristics. To date, a much attention has been given to the decoration of CNTs with nanoparticles composed of metals [26] [27] [28], metal oxides [29] [30], or metal sulfides [31] [32] due to the composites' special catalytic [33], electrical, magnetic, thermal, and optical properties [34] [35]. However, very few reports are available on the synthesis of nanofluids with Ag nanoparticles (Ag-NPs) attached to CNTs (Ag/CNTs) [36] [37], which exhibit excellent chemical and physical stability. "
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    ABSTRACT: This paper reports a significant enhancement in the thermal conductivity of silver-nanoparticle-based aqueous nanofluids with the addition of negligible amounts of multi-walled carbon nanotubes (MWCNTs). The present work was conducted using purified MWCNTs/water nanofluids prepared by a wet grinding method. Silver nanoparticles were dispersed into the MWCNT/water nanofluids via a one-step method using pulse power evaporation, which was observed to improve the dispersibility and thermal conductivity of the nanofluids. A particle sizing system (PSS) and transmission electron microscopy (TEM) were used to confirm the size of silver nanoparticles in base fluids. The PSS measurement results reveal that the size of the silver nanoparticles was approximately 100 nm, which is in good agreement with the results obtained from TEM and SEM. The maximum absorbance (2.506 abs at a wavelength of 264 nm) and highest thermal conductivity enhancement (14.5% at 40 °C) were achieved by a fluid containing ‘0.05 wt% MWCNTs–3 wt% Ag’ composite.
    Ceramics International 08/2013; 39(6):6415–6425. DOI:10.1016/j.ceramint.2013.01.069 · 2.61 Impact Factor
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    • "Metallocenes such as ferrocene have been demonstrated to be used as precursors to prepare carbon nanostructures, because they can not only act as carbon source but also give rise to small metal clusters as catalyst [16] [17] [18]. Here high-quality CSCNTs with short lengths (<3.5 lm) was grown in a quartz tube reactor inside a dual-zone furnace. "
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    ABSTRACT: The current–voltage characteristics of individual cup-stacked carbon nanotubes (CSCNTs) were investigated in situ inside the transmission electron microscope. Different from other quasi-1D carbon structures such as multi-walled carbon nanotubes, carbon nanofibers or graphitic fibers that normally behave as a metallic conductor of electrons, individual CSCNTs were found to exhibit unexpectedly semiconducting behaviors due to the special stacking microstructure of graphene layers. The band gap of the CSCNTs was obtained with the value of about 0.44 eV, in contrast to the zero-gap semiconducting quasi-2D graphene. These findings provide new information about the effect of the stacking graphene layers on their electronic properties, and will widen the usefulness of such stacking structure for the application in nanoelectronics.
    Carbon 03/2009; 47(3-47):731-736. DOI:10.1016/j.carbon.2008.11.005 · 6.20 Impact Factor
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    ABSTRACT: Various magnetic nanostructures such as Fe nanoparticles (Fe-NPs) adhering to single-walled carbon nanotubes, carbon-encapsulated Fe-NPs, Fe-NP decorated multi-walled carbon nanotubes (MWCNTs), and Fe-filled MWCNTs have been synthesized by the pyrolysis of pure ferrocene. It is found that the formation of the nanostructures can be selectively controlled by simply adjusting the sublimation temperature of ferrocene, while keeping all other experimental parameters unchanged. Magnetic characterization reveals that these nanostructures have an enhanced coercivity, higher than that of bulk Fe at room temperature. Based on the experimental results, the formation mechanism of the nanostructures is discussed in detail.
    Carbon 11/2008; 46(14). DOI:10.1016/j.carbon.2008.07.038 · 6.20 Impact Factor
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