Origins of low lattice thermal conductivity in 2D carbon allotropes

Carbon allotropes occupy significant roles in heat conduction fields. The thermal transmission in most allotropes is determined by phonons, and ultimately, fundamentally is dependent on the properties of chemical bonds. In this paper, thermal transmission in four novel 2D carbon allotropes has been studied, including penta-graphene, Psi-graphene, popgraphene and net-W by using non-equilibrium molecular dynamic (NEMD) simulations and time domain normal mode analysis (TDNMA). Graphene, the standard 2D carbon allotrope, has also been examined for comparison. Our NEMD simulated results indicate that despite of the same dimension, they possess significantly different thermal properties than that of graphene: their thermal conductivities show about 85%-95% reduction of that for graphene at room temperature. TDNMA shows that the lower thermal conductivity of penta-graphene, Psi-graphene, pop-graphene and net-W is caused by the combined action of their reduced phonon group velocities and relaxation time. Moreover, the bond difference parameter has also been applied to describe the relationship between bond properties and thermal transmission in sp(2) composed carbon allotropes. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).