LAUSR

Abstract Penta-graphene (PG), composed of carbon pentagons, has attracted considerable attention because of its unique atomic configuration and novel properties. Here, for the first time, we study the effect of grain boundaries (GBs) on the thermal transport properties of PG by using non-equilibrium molecular dynamics simulations. Compared with pristine PG, the thermal conductivity of grains in polycrystalline penta-graphenes (PPGs) decreases by about 20%. The boundary conductance of PPGs with different GBs is in a small range of 0.43 × 1010 to 0.57 × 1010 W/mK, which differs from the situation of polycrystalline graphene where the boundary conductance decreases dramatically with the increase of grain orientation angles. The critical size of the grains is found to be about 25 nm, below which the contribution from GBs to the thermal conductivity is comparable to that from the grains. This critical size is much smaller than that of polycrystalline graphene (100 nm). A detailed analysis of the phonon group velocity and vibrational density of states reveals that the geometric anisotropy and the phonon scattering induced by the GBs in PPG are the main reasons for the reduction of thermal conductivity. Our study sheds lights on tuning thermal conductivity via GB engineering in 2D materials.