▎ 摘　　要

The mechanism of spontaneous doping of boron atoms into graphene is proposed from ab-initio calculations. When boron and oxygen atoms are placed beside the graphene plane, boron can substitute spontaneously carbon atom in graphene without any energy barrier. More interestingly, the mechanism of spontaneous boron doping is reversible, i.e., the boron dopant also can be removed by the similar barrier-free process. Therefore, the mechanism of doping and contra-doping in this paper should be very useful to control boron doping of graphene. (C) 2012 Elsevier B.V. All rights reserved.