Carbon nanotubes nucleation/growth

Little, R. - Mechanistic aspects of carbon nanotubes nucleation and growth , J. 

Ni(CO)4 is the sole binary carbonyl complex of the elements of group 10 that is stable (Table 8.1). However, very few studies in which Ni(CO)4 is used in the preparation of catalysts have been reported [43]. This is probably due to the difficulty of manipulation of Ni(CO)4 and its very high toxicity. However, surface Ni(CO)4 species have been identified after the interaction of CO with highly dispersed supported nickel catalysts prepared by other routes [44]. Recent interest in the use of Ni(CO)4 has focused on the controlled production of nickel nanoparticles for specific purposes, such as in automotive converters [45]. The use of nickel tetracarbonyl as an agent for the nucleation process in the growth of single-wall carbon nanotubes has also been reported [46]. 

The methods of preparation discussed above do not involve any template and the nanoparticles of the oxide or the trisulfide act as nucleation centers for tube growth. Recently, CNTs have been used as templates to grow MoS2, WS2 and NbS2 coated carbon nanotubes, some of which contain 1-2 layers of the chalcogenide at the exterior. " The CNTs were coated with the metal oxide or its precursor and treated in a H2S/H2/N2 atmosphere at elevated temperatures to convert the oxide to the sulfide However, the CNT core was not removed in the nanostructures (Fig. IS). 

V.L. Kuznetsov, A.N. Usoltseva, A.L. Chuvilin, E.D. Obraztsova, J.M. Bonard, Ther modynamic Analysis of Nucleation of Carbon Deposits on Metal Particles and its Implication for the Growth of Single Wall carbon Nanotubes, Phys. Rev. B 64 (23) (2001) 5401 5408. 

Tsai SH, Chao CW, Lee CL, Shih HC. Bias-enhanced nucleation and growth of the aligned carbon nanotubes with open ends under microwave plasma synthesis. Appl Phys Lett 1999 74 3462. ... 

Bower C, Zhou O, Zhu W, Werder DJ, Jin S. Nucleation and growth of carbon nanotubes by microwave plasma chemical vapor deposition. Appl Phys Lett 2000 77 2767-9. 

In addition to growth of SiNWs, one-dimensional composite structures prepared by vacuum deposition of silicon clusters on CNTs also have been investigated. Hybrid silicon/carbon nanotube one-dimensional nanostructures were synthesized using a two-step CVD process (see Fig. 15.8) [18]. The spaces between the CNTs, formed through controlled nucleation in the first deposition step, allow for subsequent penetration of silane gas and a homogenous deposition of silicon clusters on the surfaces of the CNTs during the second CVD deposition step. The hybrid silicon/CNTs exhibit a high reversible capacity of 2,000 mAh/g with a 0.15% capacity loss per cycle over 25 cycles. When compared with commercially available silicon particles, in situ prepared silicon by CVD always has a smaller irreversible capacity loss in the first cycle. This may be related to the reduced amount of SiOx on the surface of the silicon particles which usually traps lithium in... 

The presence of a surfactant favors nucleation in which the polymer growth is uniform, and a homogeneous film of poly(3,4-ethylenedioxythiophene) is formed. The presence of surfactant on the surface of multiwalled carbon nanotubes increases surface wettability which permits instantaneous nucleation. ... 

Ohta Y et al (2008) Rapid growth of a single-walled carbon nanotube on an iron clusten density-functional tight-binding molecular dynamics simulations. Acs Nano 2(7) 1437-1444 Moors M et al (2009) Early stages in the nucleation process of carbon nanotubes. Acs Nano 3(3) 511-516... 

Kuznetsov, V.L., Usoltseva, A.N., Chuvilin, A.L. Thermodynamic analysis of nucleation of carbon deposits on metal particles and its implications for the growth of carbon nanotubes. Phys. Rev. B 64, 235401 (2001)... 

Zawadzak et al. have considered the development of new tissue engineering scaffolds based on highly porous and interconnected PU foams electrophoretically coated with carbon nanotubes (Zawadzak et al., 2009). These authors observed that the presence of a uniform CNT coating on the surface of PU foams accelerated the formation of calcium phosphate, an indication of the material effectiveness to form strong bonds to bone tissue, when compared to the uncoated foams, which was related to favored calcium phosphate crystal nucleation and growth induced... 

---