▎ 摘　　要

Motivated by the development of transition-metal-nitrogen-carbon (TM-N-C) materials for catalysts and molecular electronics, we investigated the electronic and magnetic properties of TMN4-graphene materials with different central atoms (TM=Ti, V, Cr, Mn, Fe, Co, Ni and Cu) and different concentrations. The first-principles results show that a widely tunable magnetic moment in the range from 0 to 4 mu(B) can be obtained in this kind of material by varying the central TM atom, and a regular transition of the electronic property from metallic to half-metallic and to semiconducting characteristics is observed in MnN4-graphene upon changing the concentration. We find that the peculiar relationship between the electronic characteristics of graphene and its lattice parameters plays a decisive role in determining the electronic and magnetic properties. Our findings are useful for the design of TM-N-C materials for catalysis, spintronics, and molectronics.