Study On The Related Properties Of Nitrogen-Doped Graphene And Its Composites

Since its first preparation in 2004, graphene has become a hotspot in the field of materials science in just a few years. Because of its excellent physical and chemical properties graphene is applied to such as energy storage, chemical, photoelectric and many other areas,graphene industries are also in the process of rapid development and maturity. With the further development of the application, unmodified pure graphene has been difficult to meet the demand, such as: the zero band gap of graphene is limiting its application in the semiconductor field; its own electrochemical performance can not fully meet the requirements of the new generation of energy storage devices and it needs to be compounded with specific materials to improve the overall performance. In this paper, the effects of nonmetallic atoms, including nitrogen atom, intercalating in graphene were studied theoretically. The composite material of nitrogen-doped graphene and SnO2 nanocrystals, and the composite material of nitrogen-doped and Li3V2(PO4)3 nanoparticles were prepared. The electrochemical properties of the composites were tested.The main research contents are as follows:1) We have investigated the band engineering and interface magnetism of epitaxial graphene on SiC(0001) by nonmetal atom doping. For the sake of comparison, we first studied the possible intercalation models of fluorine, chlorine, oxygen and nitrogen atoms, and the changes of energy band and interface magnetic after intercalation, and then summarized with the horizontal comparison. A fine tuning of the doping behavior from intrinsic n-type to charge neutrality to p-type and interface magnetism is achieved via increasing the adsorption concentration of F atoms on buffer layer. Cl doping has similar to F doping. In addition, N decoration is also a good way to induce the metal-semiconductor transition with the Dirac point moving but not disappearing, while O modification can induce a p-type doping behavior.2) The composites of Sn02 nanocrystals and nitrogen-doped graphene were prepared by hydrazine hydrate vapor reduction. The morphology, microstructure and composition of the composites were studied. In order to investigate the effects of nitrogen-doped graphene on the electrochemical properties of SnO2 nanocrystals, we made the electrochemical performance tests on the composites anode and compared with the performance of SnO2 anode.3) The composites of nitrogen-doped graphene and carbon-coated Li3V2(PO4)3 nanoparticles were prepared by an efficient method. For comparison, G-Li3V2(PO4)3/C and Li3V2(PO4)3/C were prepared by the same way. The morphology, microstructure and composition of the three samples were characterized. The electrochemical performance tests were carried out to investigate the performance improvement due to nitrogen-doped graphene.