Formation mechanism of Y-junctions in arrays of multi-walled carbon nanotubes

Abstract

a b s t r a c tTransmission electron microscopy of arrays of multi-walled carbon nanotubes reveals the presence of numerous Y-junctions. The diameter distributions of the samples are found to be bimodal, with one mode corresponding to the branches and the other mode to the trunk of the Y-junctions. The analysis of the micrographs shows that the junctions form via the merger of metal particles during the tip-growth of the tubes.

Performance enhancement of single-walled nanotube–microwave exfoliated graphene oxide composite electrodes using a stacked electrode configuration

“…8 The theoretical amount of current a CNT can carry is 10 9 A cm À2 along its length, while Young's modulus ranges from 1054-1200 GPa. 9,10 CNTs are thus able to enhance the conductivity of electrode systems. 11 The mechanical, chemical, and electronic properties, coupled with the high aspect ratio of graphene make it attractive for applications in composite materials.…”

Present and Future Perspectives of Liquid-Phase Slurry Processes Involved in Methanol and Dimethyl Ether Synthesis Using Biomass-Derived Syngas

“…Traditionally utilized hybrid catalysts for DME production are Cu–Zn–Al-type catalysts and acidic zeolite or alumina for methanol dehydration . These hybrid catalysts are prepared by either mixing a methanol synthesis catalyst (i.e., CZA) and a solid acid catalyst or combining two different types of catalysts via co-precipitation and impregnation procedures into a bifunctional catalyst. , Recently, researchers reported the catalysts made of metal oxides, such as Rh, Ti, Mg, Mn, Ce, Cr, Ca, Zn, and Zr, supported on multi-walled carbon nanotubes . Newly invented carbon-nanotube-based materials have been used for better productivity of methanol with higher selectivity for MeOH and longer life carrier/support materials, which provide surface support for the catalytically active metal catalysts, for example, Al 2 O 3 for CuO/ZnO (active state of Cu/ Zn) and other ZrO 2 , Cr 2 O 3 , and SiO 2 …”

“…40,41 Recently, researchers reported the catalysts made of metal oxides, such as Rh, Ti, Mg, Mn, Ce, Cr, Ca, Zn, and Zr, supported on multi-walled carbon nanotubes. 119 Newly invented carbon-nanotube-based materials have been used for better productivity of methanol with higher selectivity for MeOH and longer life carrier/support materials, which provide surface support for the catalytically active metal catalysts, for example, Al 2 O 3 for CuO/ZnO (active state of Cu/ Zn) and other ZrO 2 , Cr 2 O 3 , and SiO 2 . 27…”

“…However, the concept and role of the oxygen vacancy site is not wellestablished because it highly depends upon the type, size, and structure of the catalyst. Although many advancements in the catalyst have been made, only a few high-activity catalysts (MK101 by Haldor Topsøe, 6 Ni(CO) 4 by Brookhaven National Laboratory, H-ZSM, 116 carbon nanotubes, 119 photocatalysts, 90 etc.) have gained recognition to provide higher productivity and prolonged life, but their application in commercial plants is still questionable.…”

Growth mechanisms of carbon nanostructures with branched carbon nanofibers synthesized by plasma-enhanced chemical vapour deposition

“…For the CNT connections by CCVD growth, however, there are two opposite growth mechanisms. Zilli et al 18 and Luo et al 9 ascribed the connections of the CNTs to a catalystmerging mechanism: the two encountering nanoparticle catalysts weld together or undergo some kind of sintering and they subsequently act as a unique catalyst for the second CNT branch. On the contrary, Li et al 6 considered that the splitting of the catalyst particles was at the origin of the Y-type CNTs.…”