The Study Of Magnetic Properties Of Hydrogenated Graphene

Graphene,a two-dimensional sp~2 carbon material,has received immense attention for its potential application in next-generation electronic devices,energy storage devices,spintronics devices,etc.owning to its special structure and electornic properties.These properties of graphene may drastically change by adsorption of atoms like hydrogen(H)on its surface.H atom destroy the conelike dispersion of graphene and open a band gap.Hydrogenation gives us a new way for tuning the properties of graphene with unprecedented potential for applications.From graphene to semihydrogenated graphene and to fully hydrogenated graphene,the system evolves from a nonmagnetic conductor to a ferromagnetic semiconductor and to a nonmagnetic insulator.First-principles theoretical studies have predicted that adsorption of H atoms(chemisorption defects)or carbon vacancy defects in graphene can induce magnetic moments and a long-range magnetic ordering.In partically hydrogenated graphene,the breaking of the π network by absorption of H causes the formation of unpaired electrons in the oppsite sublattice which give rise to the formation of local magnetic moments.In the recent STM research,Gonzales-Herrero et al.deposited a single H atom on top of graphene and detected the spin polaration on the oppsite sublattice.However,there are rarely research on the magnetism of partial hydrogenated graphene prepared by wet chemical method.The main contents and results of our work are as follows:1.The magnetic properties of hydrogenated graphene were studied by measuring and characterizing the graphene prepared by wet chemical hydrogenation.The results showed that hydrogenated graphene presented pure Curie paramagnetism at 2 K and pure diamagnetism at 300 K,and there was no obvious ferromagnetic signal.Hydrogenation could effectively improve the saturation magnetic moment,but the magnetic induction efficiency of hydrogen was low.2.Defective graphene was prepared from fluorinated graphite and hydrogenated to improve magnetic induction efficiency.The results show that the vacancy defect can improve the magnetic induction efficiency of hydrogen to a certain extent,and the hydrogenation in a short time can improve the saturation magnetic moment,but the saturation magnetic moment decreases with increasing the hydrogenation time.