▎ 摘　　要

Polymeric graphitic carbon nitride materials exhibit exotic properties superior to graphene which are promising for applications in energy conversion, environment protection, and spintronics devices. We propose a two-dimensional (2D) framework of graphene-like carbon nitride composing of C9N7 units connected by nitrogen atoms. From first-principles, we demonstrate that this 2D carbon nitride has a spin-polarized ground state and exhibits metallic electronic properties, in contrast to commonly studied graphitic carbon nitrides which are nonmagnetic semiconductors. Additionally, half-metallicity can be achieved in this framework by applying tensile strain. The realization will be beneficial for spintronics as a candidate material for a spin-current generator. More importantly, this provides a feasible way to realize half-metallicity in experiments.