Functionalization mediates heat transport in graphene nanoflakes

Abstract

The high thermal conductivity of graphene and few-layer graphene undergoes severe degradations through contact with the substrate. Here we show experimentally that the thermal management of a micro heater is substantially improved by introducing alternative heat-escaping channels into a graphene-based film bonded to functionalized graphene oxide through amino-silane molecules. Using a resistance temperature probe for in situ monitoring we demonstrate that the hotspot temperature was lowered by ∼28 °C for a chip operating at 1,300 W cm−2. Thermal resistance probed by pulsed photothermal reflectance measurements demonstrated an improved thermal coupling due to functionalization on the graphene–graphene oxide interface. Three functionalization molecules manifest distinct interfacial thermal transport behaviour, corroborating our atomistic calculations in unveiling the role of molecular chain length and functional groups. Molecular dynamics simulations reveal that the functionalization constrains the cross-plane phonon scattering, which in turn enhances in-plane heat conduction of the bonded graphene film by recovering the long flexural phonon lifetime.

Molecular junctions for thermal transport between graphene nanoribbons: Covalent bonding vs. interdigitated chains

“…Table 1 reports Gchain values calculated from Equation 3 for all the cross-linkers schemes and chain lengths. Gchain values are found independent on the grafting scheme and therefore reflect the contribution of single chains to the interface between two nanoribbons, confirming the additive effect of the single linker reported in previous works 10,22 . Quantitatively, conductance values are aligned with results previously reported in the literature.…”

“…In an experimental and computational work, Han et al 10 exploited silane functionalization to reduce thermal resistance between substrate and supported graphene nanoflakes. Both computational and experimental results agree that the bridging molecule density tuned the thermal conductivity leading to an heat conduction enhancement.…”

A Review on Nanofluids: Fabrication, Stability, and Thermophysical Properties

“…On the other hand, the TCNTs nanofluids, of similar vol%, maintained a long-term stability (many months) with no visible precipitation at the bottom of the test vial. It is worth mentioning that surface modification technique via functionalization is not a special method used only for nanofluid but can also be employed in other applications (e.g., functionalizing graphene oxide bonded to a graphene-based film to improve thermal management) [153].…”

Improving Thermal Transport at Carbon Hybrid Interfaces by Covalent Bonds

“…However, this 1D thermal transfer cannot effectively decrease the heat density due to weak thermal conductivity and poor contact of CNT in the radial direction . On the other hand, although 2D carbon materials like graphene can be able to dilute the heat density to a certain extent, graphene cannot provide as huge surface areas for convection as 1D CNT structures. Moreover, the cross‐planar thermal conductivity of few‐layer graphene is only around 0.7 W m −1 K −1 .…”