▎ 摘　　要

The success of graphene created a new era in materials science, especially for two-dimensional (2D) materials. 2D single-crystal carbon nitride (C3N) is the first and only crystalline, hole-free, single-layer carbon nitride and its controlled large-scale synthesis has recently attracted tremendous interest in thermal transport. Here, we performed a comparative study of thermal transport between monolayer C3N and the parent graphene, and focused on the effect of temperature and strain on the thermal conductivity (kappa) of C3N, by solving the phonon Boltzmann transport equation (BTE) based on first-principles calculations. The kappa of C3N shows an anomalous temperature dependence, and the kappa of C3N at high temperatures is larger than the expected value following the common trend of kappa similar to 1/T. Moreover, the kappa of C3N is found to be increased by applying a bilateral tensile strain, despite its similar planar honeycomb structure to graphene. The underlying mechanism is revealed by providing direct evidence for the interaction between lone-pair N-s electrons and bonding electrons from C atoms in C3N based on the analysis of orbital-projected electronic structures and electron localization function (ELF). Our research not only conduct a comprehensive study on the thermal transport in graphene-like C3N, but also reveal the physical origin of its anomalous properties, which would have significant implications on the future studies of nanoscale thermal transport.