On the Stability and Abundance of Single Walled Carbon Nanotubes

Abstract

Many nanotechnological applications, using single-walled carbon nanotubes (SWNTs), are only possible with a uniform product. Thus, direct control over the product during chemical vapor deposition (CVD) growth of SWNT is desirable, and much effort has been made towards the ultimate goal of chirality-controlled growth of SWNTs. We have used density functional theory (DFT) to compute the stability of SWNT fragments of all chiralities in the series representing the targeted products for such applications, which we compare to the chiralities of the actual CVD products from all properly analyzed experiments. From this comparison we find that in 84% of the cases the experimental product represents chiralities among the most stable SWNT fragments (within 0.2 eV) from the computations. Our analysis shows that the diameter of the SWNT product is governed by the well-known relation to size of the catalytic nanoparticles, and the specific chirality is normally determined by the product’s relative stability, suggesting thermodynamic control at the early stage of product formation. Based on our findings, we discuss the effect of other experimental parameters on the chirality of the product. Furthermore, we highlight the possibility to produce any tube chirality in the context of recent published work on seeded-controlled growth.

The role of carbon precursor on carbon nanotube chirality in floating catalyst chemical vapour deposition

“…cluster beams 50,51 . Second, the chiral angle distribution ( Figure 6) shows the same variation as He et al for CO (strong arm-chair bias) and methane (flatter variation) for chirality 30 , which can be understood to be dictated by the temperature of the iron particle at CNT nucleation [52][53][54][55] . According to Artyukov et al, at low temperatures (ethanol & toluene) the nucleation mechanism is controlled by contact free-energy between the CNT and catalyst, which favours CNTs with near armchair or zig-zag configurations 53 .…”

“…Further, by using an organic template or selectively purified CNTs, the catalyst can be eliminated altogether. For example, exclusively (6,6) armchair-type SWNTs have been grown using the polycyclic hydrocarbon C 96 H 54 as an end-cap nucleating agent on a platinum (111) surface 13 and CNTs have been selectively purified and cloned on a quartz surface without the need of a catalyst 14 . However, all of these developments have been confined to substrate-bound catalysing/nucleating agents, which limit the scalability needed for industrial quantities of CNTs.…”

From cyclic nanorings to single-walled carbon nanotubes: disclosing the evolution of their electronic structure with the help of theoretical methods

“…CPH keeping intermediate values. This set of results also relates with the energetic stability of finite size tubes, which should ideally correlate with experimental abundance of SWCNT.Fixing the value of L = 6 for [6]CC,[9]CC,[12]CC, and[12]CPH, which also allows a qualitative comparison with previous theoretical estimates for all the combinations n + n = 8 − 18 for both (n, 0) and (n, n) cases,60 one can see how the FOD-based descriptors (i.e. N FOD ) and energy magnitudes (i.e.…”

Rational Design of a Low-Cost, High-Performance Metal–Organic Framework for Hydrogen Storage and Carbon Capture

“…Interestingly, the typical diameter of single-wall carbon nanotubes (SWNTs), depending on the chirality indices, can range from 6.2 ( n + m = 8) to 12.2 ( n + m = 18) for the lowest energy tube for each combination of chirality indices. 66 We have therefore designed a MOF with a channel geometry that is essentially comparable to a SWNT but with a significantly higher degree of chemical diversity due to the presence of oxygens and open metal sites decorating the inside of the channel. The proximity and increased volumetric density of open metal sites in the DHFUMA structure compared to the DOBDC structure will later be shown to result in a new CO 2 binding configuration.…”