Manipulating thermal conductance of supported graphene via surface hydroxylation of substrates

Abstract

Surface functionalization of substrates is a promising strategy to tune thermal transport in supported graphene. In this work, we have conducted molecular dynamics simulations to investigate how the surface hydroxylation of amorphous SiO2 substrate affects heat conduction in supported graphene. The results show that the thermal conductivity of supported graphene is decreased by introducing hydroxyl groups on the substrate surface. The underlying physics of thermal conductivity suppression is explained by analyzing the phonon spectral energy density, lifetime, and participation ratio. We have observed that the surface hydroxylation decreases the phonon lifetime and causes remarkable damping of out-of-plane flexural phonons. Moreover, the hydroxyl groups induce modifications of the graphene configuration, which result in the phonon localization and, correspondingly, the low thermal conductivity. Our findings highlight the importance of the substrate surface on thermal conductivity of supported graphene and provide guidance on the design of substrates to control heat transport in graphene.