Thermal conductivity and thermal rectification of nanoporous graphene: A molecular dynamics simulation

TL;DR

This study uses molecular dynamics simulations to analyze the thermal conductivity and rectification properties of nanoporous graphene, revealing size, edge, and porosity effects, and demonstrating potential for thermoelectric applications.

Contribution

It provides new insights into how nanoporous graphene's thermal properties can be tuned and exhibits significant thermal rectification due to interface effects.

Findings

Thermal conductivity of NPG is about two orders smaller than pristine graphene.

Porosity concentration effectively tunes thermal conductivity.

Large thermal rectification factor observed at interfaces.

Abstract

Using non-equilibrium molecular dynamics (NEMD) simulation, we study thermal properties of the so-called nanoporous graphene (NPG) sheet which contains a series of nanoporous in an ordered way and was synthesized recently (Science 360 (2018), 199). The dependence of thermal conductivity on sample size, edge chirality, and porosity concentration are investigated. Our results indicate that the thermal conductivity of NPG is about two orders smaller compared with of pristine graphene. Therefore this sheet can be used as a thermoelectric material. Also, the porosity concentration helps us to tune the thermal conductivity. Moreover, the results show that the thermal conductivity increases with growing sample length due to ballistic transport. On the other hand, along the armchair direction, the thermal conductivity is larger than zigzag direction. We also examined the thermal properties of the interface of NPG and graphene. The temperature drops significantly through the interface leading to the thermal resistance. The thermal resistance changes with imposed heat flux direction, and this difference cause significantly large thermal rectification factor, and heat current prefers one direction to another. Besides, to investigate those quantities fundamentally, we study the phonon density of states and scattering of them.