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石墨烯由于具有奇异的电子性质而成为多个学科研究的热门材料,其在各个领域的潜在应用也逐渐被实现.而石墨烯工业化应用的前提之一是大面积高质量石墨烯的合成.在合成石墨烯的众多方法中,过渡金属表面化学气象沉积法(CVD)作为制备大面积高质量石墨烯的主要方法而被深入研究和广泛使用.作为二维晶体的石墨烯,其生长过程应该遵循经典的晶体生长理论,因此本文从经典的晶体生长理论出发,结合密度泛函理论(DFT)对石墨烯CVD生长过程的具体计算,来介绍石墨烯的微观生长机制.主要从三个方面系统地介绍了石墨烯的CVD生长机理:(1)石墨烯在金属催化剂表面的成核过程,包括二维碳团簇在金属平台和台阶附近的成核过程和成核速率,并据此提出石墨烯在成核生长过程中的种子生长法.(2)经典的Wulff构造理论在石墨烯CVD生长中的应用,通过研究不同石墨烯边界结构在金属表面的稳定性和边界能来获得不同催化剂金属表面石墨烯晶粒的平衡态形状或能量最低结构.(3)动力学Wulff构造理论在石墨烯生长中的应用,通过研究金属原子钝化石墨烯边的稳定结构和不同边界的生长过程来研究石墨烯的生长动力学.金属原子钝化的扶手型(armchair,AC)石墨烯边界的存在大大地降低了碳原子加入到边界形成六元环所需要克服的势垒,导致了AC石墨烯边界的生长速度较快最后消失,而留下生长较慢的锯齿型(zigzag,ZZ)石墨烯边界.以上在原子尺度上对石墨烯CVD生长过程中成核和连续生长过程的微观机制研究对实验上生长大面积高质量的石墨烯材料提供了有价值的理论参考.
Graphene has become a popular material for many disciplines because of its singular electronic properties, and its potential applications in various fields are also gradually realized.One of the preconditions for the industrial application of graphene is the synthesis of large-area and high-quality graphene. Among the many methods of synthesizing graphene, chemical vapor deposition (CVD) of transition metal surface is widely studied and widely used as the main method for preparing large-area and high-quality graphene.As the two-dimensional graphene, the growth process should follow Therefore, in this paper, based on the classical theory of crystal growth, this paper introduces the mechanism of graphene’s microscopic growth by combining the density functional theory (DFT) with the specific calculation of the CVD growth process of graphene, mainly from three aspects The mechanism of CVD growth of graphene is introduced. (1) The nucleation process of graphene on the surface of metal catalyst, including the nucleation process and the nucleation rate of two-dimensional carbon clusters around the metal platform and the step, (2) The application of the classical Wulff tectonic theory in the graphene CVD growth, through the study of different graphene boundaries The stability of the metal surface and the boundary can be used to obtain the equilibrium state or the lowest energy structure of the graphene grains on different metal surfaces. (3) The application of dynamics Wulff tectonics in the growth of graphene, The graphene growth kinetics was studied by the graphene-based graphene structure and the growth of graphene at different boundaries.The existence of graded armchair (AC) graphene with metal atom passivation greatly reduced the carbon atoms added to the boundary to form hexa The potential barrier to be overcome by the ring causes the growth of the AC graphene boundary to disappear at a faster rate and leave a slower growing zigzag (ZZ) graphene boundary. The microscopic mechanism of nucleation and continuous growth during growth provides valuable theoretical references for the experimental development of large-area and high-quality graphene materials.