Doping Nanoscale Graphene Domains Improves Magnetism in Hexagonal Boron Nitride

Carbon doping can induce unique and interesting physical properties in hexagonal boron nitride (h-BN). Typically, isolated carbon atoms are doped into h-BN. Herein, however, the insertion of nanometer-scale graphene quantum dots (GQDs) is demonstrated as whole units into h-BN sheets to form h-CBN. The h-CBN is prepared by using GQDs as seed nucleations for the epitaxial growth of h-BN along the edges of GQDs without the assistance of metal catalysts. The resulting h-CBN sheets possess a uniform distrubution of GQDs in plane and a high porosity macroscopically. The h-CBN tends to form in small triangular sheets which suggests an enhanced crystallinity compared to the h-BN synthesized under the same conditions without GQDs. An enhanced ferromagnetism in the h-CBN emerges due to the spin polarization and charge asymmetry resulting from the high density of CN and CB bonds at the boundary between the GQDs and the h-BN domains. The saturation magnetic moment of h-CBN reaches 0.033 emu g^-1 at 300 K, which is three times that of as-prepared single carbon-doped h-BN.