Stable thermal transport in reduced graphene-oxide aerogel at elevated temperatures

Abstract

We investigate thermal transport in three-dimensional graphene aerogel networks at elevated temperatures. The aerogels are solution-processed from graphene-oxide flakes using amine-based linkers and then partially reduced to impart stability in the chemical structure at elevated temperatures. Thermal conductivity of the system is estimated using steady-state electrothermal technique in vacuum in the temperature interval from 30 to 200 °C. The thermal conductivity value is κ ∼ 0.2 W/mK at room temperature, and is found to be weakly dependent on temperature across the entire temperature interval. To examine the microscopic origin of this stable response, the thermal conductivity estimates are complemented with insights from temperature-dependent transient electrothermal response. We show that the temperature stable thermal insulation behaviour observed in this system can be attributed to two factors: point-defect scattering at the flake level from the remnant oxygen-functionalities which dominates over Umklapp scattering processes, and another contribution that arises from interfacial thermal resistance between flakes. The partial reduction thus achieves a delicate balance between imparting chemical stability while also retaining the dominance of point-defect phonon scattering, where the latter contributes to temperature stable thermal conductivity.