Large-Diameter Single-Wall Carbon Nanotubes Formed Alongside Small-Diameter Double-Walled Carbon Nanotubes

Samples containing a majority of either single-wall carbon nanotubes (SWCNTs) or double-walled carbon nanotubes (DWCNTs) are prepared in the same catalytic chemical vapor deposition conditions but using slightly different catalytic materials, based on alumina impregnated with iron and molybdenum salts. There is a sharp SWCNTs-to-DWCNTs transition. By contrast to the usual findings, the selectivity is not correlated to the size of the iron-based catalyst nanoparticles, nor does the transition occur upon a decreasing carbon/catalyst ratio. The result is attributed to the increasing MoO3 concentration inducing modifications of the gas atmosphere, such as the formation of more reactive C2 species through C2H4 dissociation, which thus favors the nucleation and growth of a DWCNT. In the DWCNT sample, the average diameter of the SWCNTs is higher than the average outer diameter of the DWCNTs, which is uncommon, as many authors stress that SWCNTs show a lower diameter than DWCNTs. The study could provide guidelines for the synthesis of very small diameter DWCNTs

High-throughput and consistent production of aqueous suspensions of Single-Wall Carbon Nanotubes

Understanding how to produce concentrated Carbon Nanotube (CNT) suspensions at high-throughput is key for the production of CNT-based products, as these allow for a straightforward integration of CNT powders in a variety of applications. In this work, we present three important developments for the production of aqueous suspensions using Single-Wall CNT and sodium dodecyl sulfate (SDS) as a dispersing surfactant: a reliable protocol to improve the reproducibility of CNT-SDS suspensions; a model describing how the CNT concentration evolves during sonication; a continuous-flow system allowing to upscale the production of suspensions. Combined, these findings pave the way for a deterministic production of CNT suspensions at high-volume, which is important for the manufacturing of advanced CNT devices

High-throughput and consistent production of aqueous suspensions of Single-Wall Carbon Nanotubes

Understanding how to produce concentrated Carbon Nanotube (CNT) suspensions at high-throughput is key for the production of CNT-based products, as these allow for a straightforward integration of CNT powders in a variety of applications. In this work, we present three important developments for the production of aqueous suspensions using Single-Wall CNT and sodium dodecyl sulfate (SDS) as a dispersing surfactant: a reliable protocol to improve the reproducibility of CNT-SDS suspensions; a model describing how the CNT concentration evolves during sonication; a continuous-flow system allowing to upscale the production of suspensions. Combined, these findings pave the way for a deterministic production of CNT suspensions at high-volume, which is important for the manufacturing of advanced CNT devices

Roll to roll coating of carbon nanotube films for electro thermal heating

Carbon nanotube (CNT) films are gaining traction in applications such as transparent conductive films, electro-magnetic shields and thin film heaters. However, to date, few cost-effective large-area CNT coating methods have been reported. Here, we present a roll-to-roll (R2R) slot-die coating process for thin film CNT heaters. In this process, a CNT suspension is continuously coated on a PET film substrate and subsequently dried and packaged. This process allows for continuous square-meter-size CNT coating. The electrical resistance and thermal map of these samples are measured by high definition infrared (IR) thermography. Anti-/de-icing demonstrations of R2R CNT coated samples are performed inside a cold room and outdoor atmospheric icing conditions. The successful R2R coating of CNTs and anti-/de-icing demonstrations show promise for application of CNTs in large area applications, such as the de-icing of ships, for which strict regulations are put in place for vessels operating in polar waters