▎ 摘　　要

First-principles computations revealed that iodine (I) is an ideal terminal group for zigzag graphene nanoribbons (zGNRs) in terms of stabilizing the pure sp (2) coordinated edges and preserving the edge magnetism. Due to the strong steric effect of I atoms, the unfavorable sp (3) coordination can be efficiently suppressed and the pure sp (2) coordinated edges can be stabilized at rather feasible experimental conditions. Interestingly, the electronic structures of I-terminated zGNRs (I-zGNRs) with different edge configurations can be well rationalized by employing the Clar's model. I-zGNRs can well reproduce the electronic and magnetic properties of those hydrogen-terminated zGNRs. Remarkably, I termination can significantly lower the critical electric field required to induce the half-metallic behavior. These results open new opportunities in fabricating spintronics devices based on zGNRs.