Diameter Refinement of Semiconducting Arc Discharge Single-Walled Carbon Nanotubes via Density Gradient Ultracentrifugation

Abstract

Arc discharge single-walled carbon nanotubes (SWCNTs) possess superlative optical and electronic properties that are of high interest for technologically important applications including fiber optic communications, biomedical imaging, and field-effect transistors. However, as-grown arc discharge SWCNTs possess a mixture of metallic and semiconducting species in addition to a wide diameter distribution (1.2 to 1.7 nm) that limit their performance in devices. While previous postsynthetic sorting efforts have achieved separation by electronic type and diameter refinement for metallic arc discharge SWCNTs, tight diameter distributions of semiconducting arc discharge SWCNTs have not yet been realized. Herein, we present two advances in density gradient ultracentrifugation that enable the isolation of high purity (>99%) semiconducting arc discharge SWCNTs with narrow diameter distributions centered at ∼1.6 and ∼1.4 nm. The resulting diameter-refined populations of semiconducting arc discharge SWCNTs possess monodisperse characteristics that are well-suited for high-performance optical and electronic technologies.

Thickness sorting of two-dimensional transition metal dichalcogenides via copolymer-assisted density gradient ultracentrifugation

“…Originally used for biomolecule separations 24 , DGU has emerged as one of the leading techniques for isolating structurally and electronically monodisperse populations of carbon nanotubes [25][26][27] and graphene 28 . The physical structure of carbon nanomaterials coupled with their surrounding hydrated amphiphilic surfactants in aqueous solution leads to subtle buoyant density differences that drive separation to their respective isopycnic points when subjected to ultracentrifugation in a density gradient medium.…”

Assembly and Electronic Applications of Colloidal Nanomaterials

“…[159] In the best case, semiconducting SWCNTs with greater than 99% purity have been isolated by this approach. [119,125,132,170] Stepwise or nonlinear density gradients have also been successfully employed. [163,164] Following sorting, it is necessary to strip the poorly conductive conjugated polymers from the tube walls to improve the charge transport, but their strong affinity for SWCNTs defies effective removal through rinsing at low temperatures.…”

“…[157,161] In addition, single-handedness SWCNT enantiomers have been separated using conjugated polymers with chiral moieties. [170,171] DGU approaches can be classified into two categories: rate-zonal DGU (sometimes referred to as transient DGU) and isopycnic DGU (sometimes referred to as equilibrium DGU). [165] One method for releasing these polymers is to trigger their conformation change by acids [166] or chelating agents.…”

Characterization of carbon nanotubes and analytical methods for their determination in environmental and biological samples: A review

“…Metallic and semiconductive SWNTs with different chirality dispersed with sodium cholate (a biliary acid derivative) were successfully separated by DGU [141]. Recently, Seo et al [142] described the isolation of high purity arc discharge SWCNTs (>99%) with narrow diameter distributions centered at 1.6 and 1.4 nm.…”