High-precision solid catalysts for investigation of carbon nanotube synthesis and structure

Abstract

The direct growth of single-walled carbon nanotubes (SWCNTs) with narrow chiral distribution remains elusive despite substantial benefits in properties and applications. Nanoparticle catalysts are vital for SWCNT and more generally nanomaterial synthesis, but understanding their effect is limited. Solid catalysts show promise in achieving chirality-controlled growth, but poor size control and synthesis efficiency hampers advancement. Here, we demonstrate the first synthesis of refractory metal nanoparticles (W, Mo, and Re) with near-monodisperse sizes. High concentrations (N = 105 to 107 cm−3) of nanoparticles (diameter 1 to 5 nm) are produced and reduced in a single process, enabling SWCNT synthesis with controlled chiral angles of 19° ± 5°, demonstrating abundance >93%. These results confirm the interface thermodynamics and kinetic growth theory mechanism, which has been extended here to include temporal dependence of fast-growing chiralities. The solid catalysts are further shown effective via floating catalyst growth, offering efficient production possibilities.

Synthesis of Carbon Nanotubes by Floating Catalyst Chemical Vapor Deposition and Their Applications

“…Boies et al also developed a size-selective solid catalyst (W, Mo, and Re) floating CVD for SWCNT chirality control. [134] With a high carbon concentration growth environment, all three types of catalyst with different symmetries generated similar almost (2n, n) chirality SWCNTs, which are incongruous with symmetry-matching theory. [135][136][137] All visible (2n, n), (2n ± 1/2n, n), and (2n ± 2/2n ± 1/2n, n) chiralities reached combined abundances of ≈74, ≈81, and ≈90% for W, Mo, and Re, respectively.…”

Utilization of Multifunctional Environment‐Friendly Organic Dopants Inspired from Nature for Carbon Nanotube‐Based Planar Heterojunction Silicon Solar Cells

“…Regarding the choice of CNTs, aerosol-synthesized single-walled CNT films were used as the electrode. [25,26] The CNTs possessed uniform diameters of 1.3-2.0 nm and the tube length of 1-5 μm. [27] The film thickness was estimated to be approximately 40 nm according to Qian et al [20] The degrees of the p-doping capability of the four natural acids were measured by the four-probe van der Paw method, Raman and visible to near-infrared (vis-NIR) spectroscopy, photoelectron yield spectroscopy (PYS), and X-ray photoelectron spectroscopy (XPS).…”

Precise Synthesis of Carbon Nanotubes and One‐Dimensional Hybrids from Templates†

“…[ 52,65,127 ] The (2 n , n ) and ( n , n –1) SWCNTs with the preferential growth kinetics were prepared assisted with the catalyst structure and symmetry. [ 128,241‐242 ] These fast‐growing chirality SWCNTs could be explained by the interface thermodynamics and kinetic growth theory mechanism. These findings give us new insights into the chirality‐controlled growth of SWCNTs, i.e ., the highly selective growth of SWCNTs can only be achieved when using right catalyst structural matching presents thermodynamic ascendancy together with proper growth kinetics.…”