The effect of doped nitrogen and vacancy on thermal conductivity of graphenenanoribbon from nonequilibrium molecular dynamics

Abstract

Graphene has become one of the most exciting topics of nano-material research in recent years because of its unique thermal properties. Nitrogen doping and vacancy defects are utilized to modify the characteristics of graphene in order to understand and control the heat transfer process of graphene. We use nonequilibrium molecular dynamics to calculate the thermal conductivity of armchair graphenenanoribbon affected by nitrogen doping concentration and nitrogen doping location, and analyze theoretically the cause of the change of thermal conductivity. The research shows that the thermal conductivity drops sharply when graphenenanoribbon is doped by nitrogen. When nitrogen doping concentration is up to 30%, the thermal conductivity drops by 75.8%. When the location of nitrogen doping moves from the cold bath to the thermal bath, the thermal conductivity first decreases and then increases. And it is also found that the structure of triangular single-nitrogen-doped graphenenanoribbon is inhibited more strongly in the heat transfer process than that of parallel various-nitrogen-doped graphenenanoribbon. Vacancy defects reduce the thermal conductivity of graphenenanoribbon. When the location of vacancy moves from the cold bath to thermal bath, the thermal conductivity first decreases and then increases. When the vacancy position is located at 3/10 of the entire length relative to the edge of the cold bath, the thermal conductivity reaches a minimum value. This is because of the phonon velocity and phonon mean free path varying with the concentration and the location of nitrogen doping and the location of vacancy defect. These results are useful to control the heat transfer process of nanoscalegraphene and provide theoretical support for the synthesis of new materials.