Mechanism of the Effect of NiCo, Ni and Co Catalysts on the Yield of Single-Wall Carbon Nanotubes Formed by Pulsed Nd:YAG Laser Ablation

Abstract

We revealed that the yield of SWNTs formed by Nd:YAG laser ablation depends on the target composition with yields following the order C x Ni y Co y > C x Ni y ≫ C x Co z . The SWNT bundles in the web formed when using the C x Ni y Co y target (web-C x Ni y Co y ) is thicker and longer than those in the web-C x Ni y . The diameters of the SWNTs in the web-C x Ni y Co y were larger and more uniform than those of the SWNTs in the web-C x Ni y . The NiCo particles in the web-C x Ni y Co y and the Ni particles in the web-C x Ni y were nanometer sized and were embedded in the amorphous carbon flakes that were dispersed throughout the weblike deposits. Filmlike deposits were formed when using the C x Co z targets, and nanometer-sized Co particles in these deposits were localized within sub-millimeter-sized areas. Examination of the target surfaces revealed that Ni emits from the C x Ni y target more efficiently than NiCo from the C x Ni y Co y target or Co from the C x Co z target during the laser ablation. On the basis of these results, we provide an explanation of how the yield and structure of SWNTs formed by laser ablation depend on the species of the metal catalysts.

Carbon nanotubes for ultrafast fibre lasers

“…The first and most applicable catalysts are Ni, Fe and Co and their 1:1 mixture [98]. It is worth noticing that bimetallic catalysts are more productive [100]. Application of other catalytic particles, for example, platinum, sulfur, molybdenum or yttrium, did not demonstrate high-yield or high-quality CNT formation.…”

Milestones in molecular dynamics simulations of single-walled carbon nanotube formation: A brief critical review

“…The latter also catalyzes carbon feedstock creation from incoming CO molecules. Later observations by Yudasaka et al, who employed laser evaporation experiments with several laser target materials [15], indicated that the metal particles are in fact molten carbide droplets, which segregate carbon during cooling. At the same time it became commonplace in the catalytic chemical vapor decomposition (CCVD) community to discriminate between "root (or base) growth" [23,37], in which the metal particles remain on a substrate, and "tip growth" [23], in which the metal particle is not anchored on the substrate surface.…”

“…For SWNT growth on nm-size particles of Au, Ag, and Ni, Takagi et al demonstrated that the size of the catalyst particles plays a crucial role in determining their catalytic activity [13]. Since the earliest days of SWNT research, the metal catalysts were believed to play essential roles in the nucleation and continued growth processes of SWNTs at high temperature [9,14,15]. Metal-free SWNT growth has not been achieved until rather recently [16 19], with earlier efforts in this direction presumably being discouraged by the observation that noncatalytic carbon-arc synthetic routes had led only to multiwalled carbon nanotubes (MWNTs) [20], which are assumed to crystallize in supercooled liquid carbon droplets [11].…”

Experimental and theoretical studies of particle generation after laser ablation of copper with a background gas at atmospheric pressure

“…laser fluence and wavelength, pulse duration, carrier gas type, pressure, and flow rate [15][16][17][18]. Experiments such as light scattering and photoluminescence have been used for real-time imaging of the particle production process to study the effects of different experimental parameters [5,19,20].…”