Professor Zhang Jin and academician Liu Zhongfan of Peking University have made important progress in the preparation of graphene film

The exploration and preparation of new low dimensional carbon materials is an important challenge in the field of nano carbon materials Graphiyne is a kind of two-dimensional (2D) carbon allotrope material, which is composed of two hybrid carbon atoms SP and SP 2 It has a well distributed pore structure in the two-dimensional plane, so it has the same structure with fullerene (0d), carbon nanotubes (1D) and graphene (2D ）At the same time, the existence of alkyne bond endows graphite alkyne with different physical and chemical properties from carbon materials only composed of SP 2 carbon atoms For example, scientists predict that graphene (GDY) is a potential nanoelectronic material with a band gap of 0.44ev-1.47 EV, and can maintain a high carrier mobility of 104-105cm 2 v-1s-1 at room temperature In addition, the large π conjugated system and ordered porous topological structure make it show great application prospects in the fields of catalysis, energy and gas separation The controlled synthesis of single-layer or few-layer graphene film is the premise of obtaining its intrinsic structure and physical properties, and it is also the core issue of the development of graphene materials Since 2010, Li Yuliang, academician of the Institute of chemistry, Chinese Academy of Sciences, has used wet chemical method to synthesize graphene film for the first time (with a thickness of about 1 μ M ）Since then, a series of methods based on wet chemistry have been developed to try to further improve the quality of graphene film, but the key scientific problems in the synthesis process still need to be solved urgently: how to restrain the free rotation of the single bond connecting the benzene ring and the alkyne bond in the monomer; how to meet the lattice matching between the substrate surface and graphene; how to control the monomer molecules on the substrate surface Aggregation and nucleation In view of the above problems, Professor Zhang Jin's research group and academician Liu Zhongfan's research group of Peking University proposed the liquid-phase van der Waals epitaxial growth method of a few layers of graphene film with graphene as the template Based on the two-dimensional graphene of atomic level, the coupling reaction was carried out at room temperature with very low monomer concentration (0.04mm) By the method of van der Waals epitaxy in solution phase, a large area of uniform and continuous high-quality and few layers of graphene film was successfully prepared The high-quality single crystal structure was confirmed by high-resolution transmission electron microscopy and spectroscopic characterization Based on the theoretical analysis, it is confirmed that the film is a three-layer structure of ABC stack The electron diffraction shows that the film has two sets of single crystal diffraction points, which correspond to the single crystal diffraction patterns of graphene and graphene respectively The results show that the angle between the lattice orientation of graphene and the growth of graphene is 14 ° The results of high resolution transmission electron microscopy (source: SCI Adv.) the method of epitaxial growth of GDN on graphene by van der Waals can be extended to other two-dimensional materials In order to study the electrical properties of the graphene film, they tried to synthesize the graphene film on the hexagonal boron nitride substrate, and preliminarily determined the electrical properties of the obtained graphene film The experimental results show that the graphene film has good conductivity (the calculated conductivity is 3180s m-1), and shows some semiconductor properties This work provides strong evidence for the stable existence of the structure of graphene, and provides a basis for the study of the basic properties of graphene and the application of graphene film The work was published in SCI Adv (DOI: 10.1126 / sciadv Aat6378) The work is supported by NSFC, national key R & D plan of the Ministry of science and technology, Beijing Science and Technology Commission and other supporting projects.