P-Superdoped Graphene: Synthesis and Magnetic Properties.

Phosphorus (P)-doping in vacancies of graphene sheets can significantly change graphene's physical and chemical properties. Generally, a high P-doping level is difficult due to the low concentration of vacancy, but is needed to obtain graphene with the desired properties. Here, we report the synthesis of P-superdoped graphene (PG) with the very high P content of 6.40 at.% by thermal annealing of fluorographite (FGi) in P vapour. Moreover, we show that the P-doping level can be tuned in the wide range from 2.86 to 6.40 at.% by changing the mass ratio of red phosphorus to FGi. The magnetic results show that (i) P-doping can effectively create localized magnetic moments in graphene; (ii) the higher doping level of sp3-type POx groups, the higher magnetization of PG; and (iii) the high P-doping levels can lead to the coexistence of antiferromagnetic and ferromagnetic behavior. It is proposed that the sp3-type POx groups are the major magnetic sources.