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Zigzag bilayer graphene nanoribbons are gapless, which is not good at the design of graphene field effect transistors. The edge line defects can open the band gap and the edge state localized on both sides may be tuned on one side, which provides theoretical support for the design of bilayer graphene nanodevices. The energy spectrum and lattice wave function of bilayer zigzag graphene nanoribbons are calculated by using the tight-binding model. The numerical results show that the hopping between edge line defects can open the AA stacking gap, and the on-site energy of edge line defects can open the AB stacking gap. The weak localization behavior in the bilayer zigzag graphene nanoribbons is different from that of single layer. The defect on-site energy and interlayer hopping can change the localized edge state, respectively. Appropriate defect on-site energy can make the electrons dominant in the upper layer (or lower layer). The electron transport of two-terminal bilayer zigzag graphene nanoribbons was investigated by using the non-equilibrium Green's function method, and the local state density and transmission probability of the system with edge defect were calculated. [ABSTRACT FROM AUTHOR]

To address the disadvantages of poor electrical conductivity, low ion mobility and excessive volume expansion of CogC)4, this thesis modified CO3O4 by preparing nanoscale composites by means of composite with graphene nanoribbons(GNRs), using the characteristics of large specific surface area, high aspect ratio and many oxygen containing groups of GNRs. The composite Co$04@GNRs was prepared by precipitating the cobalt source with ammonia in one step. The microscopic morphology and crystal structure were characterized by SEM, XRD, TEM, Raman and XPS for the composites. The results showed that the size of C03O4 particles in the nanocomposites was about 5 8 nm, attached to the edges and surfaces of GNRs, The carbon content of Co304@GNRs is about 10. 41 %, with better electrochemical properties. The electrochemical performance was obtained by assembling into Li ion half batteries, and the capacity was maintained at 787. 1 mAh/g for 100 cycles, and the discharge capacity could reach 151. 1 mAh/g when the current density was 8 000 mA/g. The improved electrochemical performance was mainly attributed to the unique nanostructure of the composite Co304 @GNRs. In the conversion type reaction, Co304 usually forms metal monomers during the charging and discharging process, causing the problem of material volume expansion. In this study, GNRs with large specific surface area, high aspect ratio and more oxygen containing groups can load more Co304 particles to improve the electrical conductivity and ion mobility of the material and moderate the volume expansion effect, thus increasing the material transport capacity and contributing to the improvement of the energy storage performance of the anode material. [ABSTRACT FROM AUTHOR]

The mass production of graphene is the core of the industrialization of graphene. One of the key issues is the preparation of graphene. The existing preparation methods can be mainly divided into four types: physical, chemical, organic chemical bonding, and doping. The latest research progress of these four types is introduced in detail, and the research mechanism and preparation process of various methods are described. The current status of research at home and abroad is reported, the relevant research results are enumerated, and the performance and growth characteristics of graphene products prepared by different methods are separately described. By discussing the differences between different research methods and the quality of the product graphene, it is concluded that the doping method with elements is the most likely method for industrialization of graphene. Finally, the general application scope of different methods is summarized. It is proposed that the doping method with elements is the most promising preparation method for realizing the industrialization of graphene. It also gives a perspective on continuing the in-depth research and exploring the potential of this method. [ABSTRACT FROM AUTHOR]