In recent years, graphene as a new type of carbon material has attracted people's attention and great interest because of its unique and outstanding properties. The controllable preparation of graphene is a precondition for the basic research and application development of graphene, and it is one of the major scientific issues to be solved urgently. Among many methods for preparing graphene, chemical vapor deposition (CVD) has become one of the most important methods for the growth of graphene because it combines the advantages of high quality and macro-preparation.
Recently, the key laboratory of organic solids of the Institute of Chemistry, Chinese Academy of Sciences, and related researchers of Peking University, Beijing Normal University, and Tsinghua University have made important series of advances in the controlled preparation of high-quality graphene using CVD methods. The results of the research are published in Adv. Mater. and Adv. Funct. Mater.
Graded-Grade Graphene Laminated Growth: Using a CVD method with liquid copper as a catalyst and methane as a carbon source, a series of graphene complexes with three-dimensional structures were obtained by adjusting the ratio of Ar and H2 flow rates (Figure 1). left). The complex has a high degree of sixfold symmetry and has a pronounced hierarchical stacking structure. For the first time, the three-dimensional growth and morphological regulation of graphene is organically combined with the dynamic regulation of non-equilibrium systems, which can in principle be extended to other two-dimensional atomic crystal materials. In addition, the graphene composites of this order structure have anisotropic electrical properties. The relevant research results were published in "Advanced Materials" (Adv. Mater. 2014, 26, 3218.) and were selected as the inner cover (right of Figure 1).
Preparation of Single Crystal Graphene Arrays: The CVD method was used to control the preparation of large-area hexagonal single crystal graphene arrays by adjusting the ratio of CH4 and H2 flow rates (Figure 2 left). Optimized growth conditions can effectively regulate monocrystalline graphene The density and size of the array are closely related to the surface fluidity of the liquid copper catalyst at high temperatures. In addition, single-crystal graphene-based field effect transistor devices show good electrical performance, laying the foundation for large-scale application of graphene. Large-area self-assembled single-crystal graphene arrays will promote the development of large-scale, high-quality graphene preparation fields, and are expected to play an important role in the future application of graphene devices. The results of the study were published in Advanced Functional Materials (Adv. Funct. Mater. 2014, 24, 1664.) and were selected as the cover article (Figure 2, right).
Controlled growth of single-crystal dodecagonal graphene: With CVD, controlled growth of dodecagonal graphene was achieved for the first time (Figure 3 left). The systematic characterization method confirmed the single-layer single-crystal characteristics of this type of graphene. For the growth mechanism of dodecagonal graphene on liquid copper, a growth model of boundary diffusion control was proposed based on experimental results. Detailed analysis shows that the boundary type of the dodecagonal graphene exhibits alternating sawtooth and armchair types. This special boundary structure is conducive to the further study of graphene spin characteristics. As a new type of monocrystalline graphene morphology, the emergence of dodecagonal graphene has added a new member to the graphene morphology family. It also provides a good object and basis for further study of the growth mechanism of graphene. The special type of boundary structure also facilitates the study of the electrical and magnetic properties of graphene. The results of the study were published in "Advanced Materials" (Adv. Mater. 2014, 26, 6423) and were selected as the inner cover (Figure 3, right).
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