Synthesis Of High-quality Carbon Nanotubes Research Articles

In-situ synthesis of high-quality carbon nanotubes on Cu powder by constructing an Al2O3 barrier layer

The synthesis of high-quality carbon nanotubes (CNTs)-Cu composite powder by chemical vapor deposition remains a persistent challenge due to catalyst deactivation resulting from its diffusion into Cu powder at elevated temperatures. To overcome this obstacle, a novel approach involving pre-coating Cu powder with an Al2O3 barrier layer was proposed to facilitate the in-situ growth of CNTs. Experimental results demonstrated that synthesized CNTs exhibited a desirable combination of uniform distribution, high aspect ratio and tunable structures achieved by utilizing different carbon source precursors. Notably, single/double-walled CNTs (S/DMCNTs) with exceptional structural integrity was achieved on Cu powder, which has not been reported previously. The Raman ID/IG ratio of present S/DMCNTs-Cu composite powder reached approximately 0.18, which was significantly superior compared to the relevant reported data.

Synthesis of high-quality carbon nanotubes by using monodisperse spherical mesoporous silica encapsulating iron oxide nanoparticles

Well-graphitized carbon nanotubes (CNTs) were grown by using monodisperse spherical mesoporous silica encapsulating single iron oxide (Fe3O4) nanoparticles (MSEINPs) as catalytic templates by chemical vapor deposition (CVD) and using acetylene as carbon source. The catalytic templates were synthesized by a sol-gel method. The MSEINPs exhibited better activity and selectivity in CNT synthesis than bare Fe3O4 catalysts. The synthesized multiwall carbon nanotubes (MWCNTs) were analyzed by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Raman spectroscopy. The carbon deposits are rich in MWCNTs, as confirmed by FESEM and TGA. The wall thickness of the MWCNTs is controlled primarily by the size of the spherical mesoporous silica layer encapsulating the Fe3O4 NPs, while the inner diameter of the CNTs is determined by the size of the Fe3O4 NPs at the center of the MSEINPs. The average diameter of the MWCNTs increased significantly with increases in the growth temperature and acetylene flow rate. The analytical results show that the CNTs prepared on MSEINPs are well graphitized with a narrow size distribution in thickness, and straight and longer tubes are obtained without major defects as compared to the CNTs grown on bare Fe3O4 NPs.

Production of Carbon Nanotubes over Fe-FSM-16 Catalytic Material: Effect of Acetylene Flow Rate and CVD Temperature

In this article, a high-yield synthesis of high-quality carbon nanotubes (CNTs) using Fe catalysts trapped within channels of Folded Sheet Mesoporous Materials, FSM-16, by chemical vapor deposition (CVD), using acetylene as a hydrocarbon source, is reported. The effect of reaction temperature and acetylene flow rate on the formation of CNTs was investigated. It was found that the yield, diameter and quality of CNTs synthesized strongly depend on reaction temperature during CVD. The resulting materials were characterized by scanning electron microscopy, Raman spectroscopy and thermogravimetric analysis. Our research found that carbon deposition, diameter and quality of the CNTs strongly depend on CVD temperature. However, the acetylene flow rate did not have any significant effect on diameter distribution. Raman measurement indicated that the synthesized products were multi-walled carbon nanotubes (MWCNTs). High-resolution transmission electron micrographs of samples reveal the multi-layer sidewalls of individual MWCNTs with a diameter of 40 nm, in which hollow and tubal structures were observed.

2305 SiC表面分解法による高配向カーボンナノチューブ膜の界面強度(要旨講演,一般セッション:マイクロナノ理工学)

Since the discovery of carbon nanotubes(CNTs), the remarkable structural, electrical and mechanical properties as carbon material has attracted many researchers, and the synthesis of high quality CNTs using various methods have studied. Kusunoki et al. have reported that CNTs with high-density and well-alignment are formed vertically on a silicon carbide substrate. CNTs on SiC substrate could be used for tribomaterial as high friction or wear proof materials because each CNT covalently bonds with the SiC substrate. Thus, we have studied about interface strength of CNT film by means of the combination of AFM nanoscratch test and finite element analysis. From the result, we could assume that shear strength at the interface of CNT films was about 180 MPa. And it was no dependency on the length of CNT.

One-step water-assisted synthesis of high-quality carbon nanotubes directly from graphite.

At 1 atm pressure, high-quality multiwall carbon nanotubes were synthesized directly from graphite in the absence of catalyst by a one-step water-assisted method.