▎ 摘　　要

In spintronics field, the spin polarization of large-area graphene has been experimentally observed, yet its reaction to gaseous molecules remains elusive because of the lack of spin-resolved adsorption/mechanistic probe. In this work, we quantified the exchange splitting and magnetic stability of graphene on Ni(111) and found the relationship with its enhanced reactivity toward oxygen molecule in comparison to freestanding graphene and to nitrogen-doped graphene using spin density functional theory calculations with van der Waals corrections. The significant improvement in the reactivity is attributed to the formation of spin-down density of states at the Fermi level (LDOS at E-F) because of the exchange splitting. Interestingly, the LDOS at EF property is maintained on graphene atoms not bound to oxygen. Also, the spin-polarization of graphene is found to be stable under oxygen adsorption. These findings pose a new deviation from the conventional ways of improving reactivity of large-area graphene such as straining, doping, and defects introduction.