Diameter‐Selective Density Enhancement of Horizontally Aligned Single‐Walled Carbon Nanotube Arrays by Temperature‐Mediated Method

Abstract

High-density single-walled carbon nanotube (SWNT) arrays with specific diameters are pursued as potential building blocks in future nanoelectronic devices. The direct growth of SWNT arrays on the single-crystal substrate has proved offering densely packing high-quality SWNTs. However, further increase of SWNT density is limited by the deactivation of the catalyst nanoparticles during chemical vapor deposition process. Moreover, an increase of array density without any structure control of SWNTs would make the benefit effect very limited. Here, a temperature-mediated method is proposed to achieve a highdensity SWNT array with a specific diameter via continual growth of SWNTs after reactivating poisoned catalysts with high carbon capacity and appropriate size. The density of obtained SWNT array on the quartz substrate is increased by more than three times, with diameter distribution controlled ≈2 nm. This approach paves the way for the integration of SWNTs into nanodevices.

Pulsed Current for Diameter-Controlled Carbon Nanotubes and Hybrid Carbon Nanostructures in Electrolysis of Captured Carbon Dioxide

“…6,7 However, the diameter of a nanotube has a major impact on both its mechanical and electrical characteristics, 5,8 with small-diameter MWCNTs (<30 nm) being the most valuable for many of these applications, but with the challenge of smaller MWCNTs involving more precise and difficult synthesis methods. 9−12 In this regard, a large number of efforts have been made using different CNT synthesis methods, such as chemical vapor deposition, 13−15 to control properties of MWCNTs using different catalysts, 16−18 temperatures, 19 and reaction gas mixtures. 20 One difficulty of conventional methods in influencing diameters and properties of nanotubes is the impact of secondary gas reactions that can occur, which complicate a simple picture between the carbon flux into the reactor and the MWCNT yield coming out.…”

“…Multiwalled carbon nanotubes (MWCNTs) are remarkable nanostructured materials with excellent electrical conductivity, high thermal conductivity, and exceptional mechanical properties . These properties, among others, make MWCNT attractive for a range of applications, including electronics, energy storage, and biological systems. , However, the diameter of a nanotube has a major impact on both its mechanical and electrical characteristics, , with small-diameter MWCNTs (<30 nm) being the most valuable for many of these applications, but with the challenge of smaller MWCNTs involving more precise and difficult synthesis methods. − In this regard, a large number of efforts have been made using different CNT synthesis methods, such as chemical vapor deposition, − to control properties of MWCNTs using different catalysts, − temperatures, and reaction gas mixtures . One difficulty of conventional methods in influencing diameters and properties of nanotubes is the impact of secondary gas reactions that can occur, which complicate a simple picture between the carbon flux into the reactor and the MWCNT yield coming out. , Additionally, scaling these traditional methods involves large capital equipment, complex secondary chemistries, and hence higher cost than other conventional carbons, limiting applications for carbon nanotubes. , …”

Anisotropic Optical Properties of Monolayer Aligned Single‐Walled Carbon Nanotubes

“…In this regard, singlewalled carbon nanotubes (SWCNTs) are the perfect candidates to form anisotropic monolayer film with a centimeter-scale required for the majority of applications. [29][30][31] Nevertheless, even for SWCNTs, the standard growth process [32,33] also produces random orientation of nanotubes resulting in effectively isotropic media. [34,35] Previously, the most common strategy to obtain aligned SWCNTs was performing the post synthesis processing that requires suspending of nanotubes leading in example to reduction of their average length.…”