▎ 摘　　要

Chemical doping is an effective method to intrinsically modify the chemical and electronic property of graphene. We propose a novel approach to synthesize the nitrogen-doped graphene via thermal annealing graphene with urea, in which the nitrogen source can be controllably released from the urea by varying the annealed temperature and time. The doped N content and the configuration N as well as the thermal stabilities are also evaluated with X-ray photoelectron spectroscopy and Raman spectra. Electrical measurements indicate that the conductivity of doped graphene can be well regulated with the N content. The method is expected to produce large scale and controllable N-doped graphene sheets for a variety of potential applications.