Intercalation Chemistry and Electronic Structure of Graphite-Like Layered Material BC[sub 2]N

A graphite-like layered material of composition BC x N y ͑x = 2.0-2.4,y = 0.8-0.9͒,which is called BC 2 N in this paper, was prepared by a chemical vapor deposition method at 1770-2220 K. Lithium ͑Li͒ and potassium ͑K͒ were intercalated into BC 2 N by an electrochemical method and a vapor-phase reaction, respectively, to make the first-stage compounds with interlayer spacings similar to those of the first-stage graphite intercalation compounds.Sodium ͑Na͒ was intercalated into BC 2 N by the electrochemical method as well as the vapor-phase reaction, whereas Na was hardly intercalated into graphite.The X-ray diffraction analysis and an electrochemical capacity suggested that the Na-intercalated BC 2 N was a mixture of the first-and second-stage compounds.X-ray absorption spectroscopy indicated that an unoccupied ‫ء‬ orbital of BC 2 N showed a relatively strong intensity, and the bottom of the orbital was at an energy lower than each bottom of graphite, noncrystalline carbon, and BC 6 N.These results suggested that alkali metals including Na could donate electrons to BC 2 N more efficiently than the other host materials.Thus, the intercalation of alkali metal into BC 2 N proceeds more effectively than the other host materials.