Water-Assisted Preparation of High-Purity Semiconducting (14,4) Carbon Nanotubes

Abstract

Semiconducting single-walled carbon nanotubes (s-SWNTs) with diameters of 1.0-1.5 nm (with similar bandgap to crystalline silicon) are highly desired for nanoelectronics. Up to date, the highest reported content of s-SWNTs as-grown is ∼97%, which is still far below the daunting requirements of high-end applications. Herein, we report a feasible and green pathway to use HO vapor to modulate the structure of the intermetallic WCo nanocrystals. By using the resultant WCo nanocatalysts with a high percentage of (1 0 10) planes as structural templates, we realized the direct growth of s-SWNT with the purity of ∼99%, in which ∼97% is (14,4) tubes (diameter 1.29 nm). HO can also act as an environmentally friendly and facile etchant for eliminating metallic SWNTs, and the content of s-SWNTs was further improved to 99.8% and (14,4) tubes to 98.6%. High purity s-SWNTs with even bandgap determined by their uniform structure can be used for the exquisite applications in different fields.

Single‐Walled Carbon Nanotubes in Emerging Solar Cells: Synthesis and Electrode Applications

“…One breakthrough was reported by Li and co-workers, who proposed a novel catalyst using the combination of Co and W (Figure 4a). [79,80] The selectivity of the Co-W catalyst was confirmed in the follow-up study, where Co-W catalysts were prepared by a different method and an intermediate structure of Co 6 W 6 C was identified. These solid catalysts follow a vapor-solid-solid model and selectively produce (12,6) SWNTs from the (0,0,12) facet.…”

Understanding the “Activation” of the Nanocluster [HxPMo12O40⊂H4Mo72Fe30(O2CMe)15O254(H2O)98-y(EtOH)y] for Low Temperature Growth of Carbon Nanotubes

“…Thus, the use of catalyst promoters likely serves two roles, (1) to replenish the number of metal atoms lost to sublimation, and (2) to reduce the reduction temperature of procatalyst FeMoC into an ''active'' catalyst. Future work will study the catalyst pre-treatment influence on the resulting phase(s) of FeMoC's Fe-Mo catalyst system; akin to the work of Li et al [13][14][15] …”

“…Considering the problems in controlling the composition and size of binary metal oxide nanoparticles [12] single molecular precursors would be considered an ideal solution: given the unique composition and hence size of the final nanoparticle. Recently, Li et al used the molecular nanocluster Na 15 [Na 3 ,{Co(H 2 O) 4 (12,6), (14,4), and (16,0) CNTs in efficiencies of 92, 97, and 80% respectively [13][14][15]. They propose the high chiral selectivity arises from two key factors: 1) the excellent matching between the (n,m) nanotube chirality and the Miller (plane) indices of the l-phase W 6 Co 7 alloy, and 2) the stability of the high melting point alloy that maintains its well-defined structure under CVD conditions.…”

Growth of Single‐Walled Carbon Nanotubes with Different Chirality on Same Solid Cobalt Catalysts at Low Temperature

“…Currently, epitaxial growth from well‐defined seeds, such as solid catalysts and segments of carbon nanotubes, has been thought to be the most promising strategy to realize this goal. At present, mainly high temperature solid catalysts were developed to realize structure‐controlled growth of SWNTs.…”

“…For example, using Mo 2 C and WC solid catalysts, a few (2 m , m ) SWNTs, such as (12, 6) and (8, 4), have been synthesized respectively with symmetry‐matching mechanism . Moreover, using W 6 Co 7 solid catalysts, recent progresses enable the synthesis of (12, 6), (16, 0), and (14, 4) tubes with structure‐matching growth mechanism. Both two mechanisms imply the thermodynamic nucleation mechanism for SWNTs on solid catalysts.…”