▎ 摘　　要

We investigate by means of ab-initio simulations the formation energy and the electronic properties of substitutional N doping in graphene with distinct grain boundary defects as a function of the N concentration. Our results show that the presence of substitutional N atoms along the defective regions is quite likely for several N concentrations. Also, we find either semiconducting or metallic structures, depending on the N concentration. Confinement effects were also investigated for the semiconducting structures. We find that the distance between the defect lines can modulate the band structure of those semiconducting N doped lines. This opens an interesting possibility to produce two-dimensional heterojunctions composed by N doped grain boundaries with different distances between the defect lines.