Substrate effects on the thermal performance of in-plane graphene/hexagonal boron nitride heterostructures

Interfacial thermal conductance G and effective thermal conductivity k of both freestanding and silica supported in-plane graphene/hexagonal boron nitride (Gr/h-BN) heterostructures are investigated via molecular dynamics simulations. The predicted G values (similar to 10(10) Wm(-2)K(-1)) are 3-4 orders larger than that of the van der Waals interfaces. Thermal rectification is found in such Gr/h-BN heterostructures for both freestanding and supported ones due to the mismatch of phonon spectra interrelated with temperature. Compared to the freestanding Gr/h-BN, an enhancement in the interfacial thermal transport is observed in supported ones and G becomes larger with increased substrate coupling. The calculated k is about 116-130 Wm(-1)K(-1) for both freestanding and supported Gr/h-BN heterostructures in the temperature range from 200 to 600 K. A weaker temperature dependence is found in the k values compared with that of G, which is resulted from the inconsistent variation of thermal transport in single materials and across the interface with temperature. Our study offers perspectives of modulating thermal properties of two-dimensional heterostructures through surface interactions with the substrate, which can contribute to promoting its potential applications. (c) 2018 Elsevier Ltd. All rights reserved.