Ultra-high thermal conductivity of two-dimensional C 23 .

High thermal conductivity is of great interest due to the novel applications in high-performance heat dissipation for microelectronic devices. Two-dimensional (2D) materials with graphene as a representative have attracted tremendous interest due to the excellent properties, where C 23 is an emerging 2D allotrope of carbon with a large bandgap. In this paper, by solving the Boltzmann transport equation based on state-of-the-art first-principles calculations, the C 23 is predicted to have an ultrahigh thermal conductivity of 2051.47 Wm -1 K -1 , which is on the same order of magnitude as graphene. Based on the comparative analysis among C 23 , graphene, and penta-graphene, it is shown that the unique spatial structure and the orbital hybridization of C 23 lead to weak anharmonicity, which results in the large relaxation time of phonons and finally results in ultrahigh thermal conductivity. Our study is expected to promote the comprehensive understanding of thermal transport in C 23 and shed light on future exploration of novel materials with high thermal conductivity.