Thermal Transport in Pentagonal CX₂ (X = N, P, As, and Sb)

Two-dimensional (2D) materials with a pentagonal structure have many unique physical properties and great potential for applications in electrical, thermal, and optical fields. In this paper, the intrinsic thermal transport properties of 2D pentagonal CX₂ (X = N, P, As, and Sb) are comparatively investigated. The results show that penta-CN₂ has a high thermal conductivity (302.7 W/mK), while penta-CP₂, penta-CAs₂, and penta-CSb₂ have relatively low thermal conductivities of 60.0, 36.9, and 11.8 W/mK, respectively. The main reason for the high thermal conductivity of penta-CN₂ is that the small atomic mass of the N atom is comparable to that of the C atom, resulting in a preferable pentagonal structure with stronger bonds and thus a higher phonon group velocity. The reduction in the thermal conductivity of the other three materials is mainly due to the gradually increased atomic mass from P to Sb, which reduces the phonon group velocity. In addition, the large atomic mass difference does not result in a huge enhancement of the anharmonicity or weakening of the phonon relaxation time. The present work is expected to deepen the understanding of the thermal transport of main group V 2D pentagonal carbons and pave the way for their future applications, also, providing ideas for finding potential thermal management materials.