Temperature and time dependence study of single-walled carbon nanotube growth by catalytic chemical vapor deposition

Influence of the growth conditions on the defect density of single-walled carbon nanotubes

“…The D band is theoretically non-active in Raman scattering but is activated in the presence of defects through a double resonance process involving the elastic scattering of electrons by defects [12,13]. The I G /I D ratio has been widely used to estimate the density of defects in nanotubes and graphene [12][13][14][15][16]. When the average distance between defects (L D ) in graphene is larger than a few nm, the ratio I G /I D is inversely proportional to the surface density of defects () following the relation:…”

Simulation and modeling of carbon nanotube synthesis: current trends and investigations

“…A phenomenological kinetic model was developed by Latorre et al [12] , which included all relevant steps involved in CNT growth by catalytic CVD, namely, carbon source decomposition, nanoparticle surface understanding of the elementary steps involved in the production of CNTs so as to derive a phenomenological kinetic model. They found that the best models involved [7] , (B) Khedr et al [8] , (C) Wirth et al [11] , (D) Kwok et al [13] , (E) Raji et al [16] , (F) Samandari-Masouleh et al [14] . Reproduced with permission from Elsevier (A, B, D, E) and the American Chemical Society (C, F).…”

“…carburization, carbon diffusion, nucleation, CNT growth and growth termination by catalyst deactivation or by the effect of steric hindrance. A recent investigation on the temperature and time dependence of SWCNT growth by CVD performed by Kwok et al [13] identified SWCNT growth within a relatively narrow temperature window of 700 -850 ° C, with an optimum growth time of 35 min for the cold wall reactor and 75 min for the quartz tube reactor. It was also revealed from the G/D band ratio of the Raman spectrum that when the temperature increased and time progressed, the diameter of the nanotube increased, as shown in Figures 2D and 3D.…”

“…The comparison indicates a good prediction of the nanotube dia meter. Kwok et al [13] plotted the time-dependent theoretical results and compared those results with experiments as shown in Figure 2E. Raji et al [16] compared the theoretically predicted yield of CNTs with experimental results in an acetylene-based CVD system, as shown in Figure 11C.…”

“…Hence, as a promising approach, this model could be effectively utilized to calculate the specific dependence of kinetic parameters on different carbon sources, operating conditions, and types and composition of the catalyst. The Kwok et al [13] model is transport-limited, but includes details such as the supply of carbon to the catalyst from the gas phase, the diffusion of carbon through catalyst particles and the diffusion of carbon over the nanotube surface, which makes it a good predictive tool. Samandari-Masouleh et al [14] developed an advanced model with several assumptions, namely the gas is in plug flow in the annular region along the reactor, the temperature profile in the reactor is predetermined, base growth mechanism can be chosen for CNT growth, CNTs are formed on the surface of the substrate by a first order reaction, and amorphous carbon is formed on the nanotubes by a first order reaction.…”