▎ 摘　　要

The dihydrogenation effects in the zigzag-edged graphene nanoribbons (ZGNRs) have been systematically investigated by first-principles calculations. Due to the dihydrogenation, the edges effectively turn to the so-called Klein edges, which results in localized edge states in (0, 2/3 pi) and extended bulk states in (2/3 pi, pi). Compared with monohydrogenation, the edge magnetic moment is substantially increased and the edge states get much more delocalized, which results in the most attractive observation that the energy difference between the antiferromagnetic (AFM) and ferromagnetic (FM) configurations is greatly increased by nearly one order of magnitude from the general several meV and thus the AFM ground state of certain ZGNRs becomes stable at room temperature. This suggests that the dihydrogenated ZGNRs are more promising than monohydrogenated ones for spintronic devices. Our finding provides an enlighening hint for stablizing the ground AFM state in ZGNRs.