Enhanced In-Plane Thermal Conductance of Thin Films Composed of Coaxially Combined Single-Walled Carbon Nanotubes and Boron Nitride Nanotubes

Abstract

Carbon nanotubes (CNTs) and boron nitride nanotubes (BNNTs) are one-dimensional materials with high thermal conductivity and similar crystal structures. Additionally, BNNTs feature higher thermal stability in air than CNTs. In this work, a single-walled carbon nanotube (SWCNT) film was used as a template to synthesize a BNNT coating by the chemical vapor deposition (CVD) method to form a coaxial heterostructure. Then, a contact-free steady-state infrared (IR) method was adopted to measure the in-plane sheet thermal conductance of the as-synthesized film. The heterostructured SWCNT− BNNT film demonstrates an enhanced sheet thermal conductance compared with the bare SWCNT film. The increase in sheet thermal conductance shows a reverse relationship with SWCNT film transparency. An enhancement of over 80% (from ∼3.6 to ∼6.4 μW•K −1 •sq −1 ) is attained when the BNNT coating is applied to an SWCNT film with a transparency of 87%. This increase is achieved by BNNTs serving as an additional thermal conducting path. The relationship between the thermal conductance increase and transparency of the SWCNT film is studied by a structured modeling of the SWCNT film. We also discuss the effect of annealing on the thermal conductance of SWCNTs before BNNT growth. Along with the preservation of high electrical conductance, the enhanced thermal conductance of the heterostructured SWCNT−BNNT films makes them a promising building block for thermal and optoelectronic applications. KEYWORDS: single-walled carbon nanotube film, boron nitride nanotube, van der Waals heterostructure, in-plane sheet thermal conductance, chemical vapor deposition, infrared thermography

Nanotube‐Based 1D Heterostructures Coupled by van der Waals Forces

“…Compressive strength and shape recoverability of CNT forests can be enhanced, owing to the synergistic effect between the CNTs and outer BNNT coating, [153] while thermal conductance of drydeposited SWCNT films was enhanced without much sacrificing their electrical conductance (Figure 9g). [154] As graphene-based electronics and physics have been fueled by h-BN as a support, the same should be expected for the 1D heterostructures consisting of CNTs and BNNTs. Several challenges are, however, still to be resolved for device applications of such materials: such as a uniform BN coating over the entire length of the CNTs and a good electrical contact between the metal and the inner CNTs through the BN layers.…”

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

“…Using nanotubes ( e.g ., CNTs, BN or WS 2 ) as templates can greatly boost the synthesis of new phase 1D materials from 2D materials. [ 47 ]…”

“…For example, the BN wrapped CNTs were used as a high power‐tolerant saturable absorber and are believed to have a significantly higher optical damage threshold as well as a great potential for various high‐power optical applications. [ 47‐49 ] The isolated molybdenum sulfide nanowires are believed to exhibit torsional motion not seen in the bulk, and thereby change their bandgap depending on their torsional angle, allowing potential applications in electro‐mechanical switching devices. [ 50 ]…”

Synthesis, characterisation and applications of core–shell carbon–hexagonal boron nitride nanotubes

“…The h-BN proved an effective inltrating material for the CNT array since (i) it can reduce the array air fraction because of radial thickening from the h-BN coating, (ii) the CNT maintains its original thermal conductance and (iii) the h-BN itself is equally an excellent heat conductor that adds additional pathways for heat conduction. 23,104 CNT@BN heteronanotubes offer a highly promising alternative to pure CNT assemblies as TIMs. However, although Jing et al, demonstrated a $50% improvement in thermal conductivity of their VA-CNTs subsequent to h-BN coating, a much greater increase on the order of several magnitudes is still necessary to meet the urgent demands of the electronics industry.…”

“…20 h-BN sheaths may also enhance the mechanical robustness and provide additional thermal conduction pathways along the CNT axis. [21][22][23] The emergent properties of CNT@BN heteronanotubes lend to their proposed applications as reinforcement llers in high temperature ceramic/metal matrix composites, energy dissipating devices, nanocables, high density interconnects, thermal interface materials, thermal management polymer composites and eld emitters.…”