Oxygen-assisted enhancing magnetism of cobalt-doped MoS2 and MoS2/graphene by first-principles calculation

[Display omitted] •There are discussions of magnetic performance of FM and AFM for all doping models.•Hybridization exist between Co-3d and S-3p, Mo-4d and S-3p of MoS2-Co and MoS2/Gr-Co.•The transition from half-metal to metal occurs after the introduction of graphene layer.•The O atom enhanced the magnetism of MoS2-2Co and MoS2/Gr-2Co systems.•The hybridization between Co-3d and O-2p is stronger than that between Co-3d and S-3p. The electronic structure and the magnetic properties are performed on Co doped MoS2 (MoS2-Co) and Co doped MoS2/graphene (MoS2/Gr-Co) systems based on the first principles calculations. When two Mo atoms are substituted by two Co atoms, the magnetic moments of two Co co-doped MoS2 (MoS2-2Co) and MoS2/Gr (MoS2/Gr-2Co) are 5.96 µB and 6.40 µB. The magnetic moment of MoS2-2Co increases by 0.44 µB and the transition from half-metal to metal occurs after introducing the graphene layer. Further introducing an O atom in MoS2-2Co and MoS2/Gr-2Co, the hybridization between Co-3d and O-2p is significantly stronger than that between Co-3d and S-3p.