Mechanism of large tunable thermal transport in graphene with oxygen functional groups

Abstract

Tuning thermal transport in low-dimensional systems such as nanowires and graphene is crucial for both conventional electronic device cooling and nanoscale energy conversion. Here, we explore a connection between surface functionalization and heat transport in functionalized graphene by oxygen functional groups from the first-principles approach. Compared to the high thermal conductivity of pristine graphene, our calculation demonstrates that the thermal conductivity of functionalized graphene has remarkably decreased by more than one order of magnitude, which is consistent with the experimental observations. Our analysis of phonon modes confirms that highly suppressed phonon lifetimes are responsible for this great reduction of thermal conductivity in functionalized graphene. We elucidate that the greatly shortened phonon lifetimes mainly result from the expanded phase space for phonon scatterings, while contributions from lattice anharmonicity may be negligible. Our findings shed light on the mechanism of thermal transport in oxygen-functionalized graphene and offer some valuable insights into a new strategy for tuning thermal conductivity and the exploration of new thermoelectric devices.