Surface Monocrystallization of Copper Foil for Fast Growth of Large Single-Crystal Graphene under Free Molecular Flow
Surface Monocrystallization of Copper Foil for Fast Growth of Large Single-Crystal Graphene under Free Molecular Flow
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自由分子流下铜箔表面单晶化快速生长大单晶石墨烯
DOI：
10.1002/adma.201603579
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发表时间：
2016-10-26
影响因子：
29.4
通讯作者：
Liu, Zhongfan
中科院分区：
文献类型：
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作者：
Wang, Huan;Xu, Xiaozhi;Liu, Zhongfan
DOI: 10.1002 / adma。201603579优质单晶薄膜。第一种方法包括精确控制畴的取向，使相邻畴在单晶衬底上的石墨烯外延生长过程中实现无晶界缺陷的无缝接合。第二种方法是抑制石墨烯生长过程中的成核密度，以避免可能形成的畴边界。近年来，人们在这些方向上做出了巨大的努力，包括使用昂贵的单晶生长衬底，[23-25]通过局部喂入碳前体[26]来抑制成核密度，以及对铜衬底进行耗时的预处理（例如，引入氧气、长时间退火、熔融再凝固、平滑、氧化蚀刻辅助等）。[27-32]由于抑制成核主要是通过在生长过程中降低原料浓度来实现的，因此这些方法的生长速率和产率通常很低（通常在1.8-24µm min - 1范围内，生长时间为数小时至数天）。[27-32]在此，我们提出了一种实际可扩展的方法，用于商业铜箔的表面单晶化和大型单晶石墨烯阵列的快速生长。商用多晶铜（Cu）箔在CO 2电还原、[1,2]变压器、[3]电池、[4,5]电路、[6,7]等电子工业中有着广泛的应用。[8,9]特别是，铜箔最近成为化学气相沉积（CVD）技术大批量生产高质量石墨烯薄膜的最有前途的催化衬底。[10-14]然而，商业多晶铜箔表面粗糙，缺陷、台阶和晶界丰富，这些缺陷和晶界是石墨烯成核的活性位点，导致成核密度高，取向随机。[15-18]因此，石墨烯的单晶畴尺寸是非常有限的。此外，当取向错误的畴合并在一起形成连续薄膜时，会出现降低其电学和机械性能的畴边界。因此，大规模CVD石墨烯薄膜的质量比机械剥离的石墨烯薄膜差得多。在概念和实际应用的石墨烯薄膜之间存在很大的差距。[19-22]为了最大限度地减少畴边界的不利影响，在大多数应用中，高质量的单晶石墨烯薄膜是非常理想的。为此，提出了两种可能的方法，包括在CVD过程中控制石墨烯的成核和生长，以实现大的
DOI: 10.1002/adma. 201603579 high-quality single-crystal films. The first approach involves a precise control of domain orientations, enabling a seamless coalescence of adjacent domains without grain boundary defects during the epitaxial growth of graphene on a singlecrystal substrate. The second approach involves the suppression of nucleation density in the graphene growth to avoid the possible formation of domain boundaries. Great efforts have recently been made along these directions, including the use of expensive single-crystal growth substrates,[23–25] the suppression of nucleation density via locally feeding carbon precursors [26] and the time-consuming pretreatments of Cu substrates (eg, introducing oxygen, long-time annealing, melting-resolidification, smoothing, oxidative etching-assisted etc.).[27–32] As the nucleation suppression is mostly achieved by lowering the feedstock concentration during growth, the growth rate and yield in these approaches are usually very low (typically in the range of 1.8–24 µm min− 1 and the growth time of hours to days).[27–32] Herein, we present a practically scalable approach for surface monocrystallization of commercial Cu foils and very fast growth of large single-crystalline graphene arrays. With a simple stacking structure of Cu foils, the entire surface of polycrystalline Cu foils was readily converted into inch-sizedCommercial polycrystalline copper (Cu) foil has broad applications in CO 2 electro-reduction,[1, 2] transformers,[3] batteries,[4, 5] circuitry,[6, 7] and other electronics industry.[8, 9] In particular, Cu foil has recently become the most promising catalytic substrate for mass production of high-quality graphene films via chemical vapor deposition (CVD).[10–14] However, the commercial polycrystalline Cu foil has rough surface rich of defects, steps, and grain boundaries, which function as active sites for graphene nucleation and result in high nucleation density and random orientations.[15–18] The single-crystalline domain size of graphene is hence very limited. In addition, the domain boundaries that degrade their electrical and mechanical properties appear when misoriented domains merge together toward a continuous film. Consequently, the quality of large-scale CVD graphene films is much worse than the mechanically exfoliated counterpart. There is a big gap between conceptual and practically available graphene films for applications.[19–22] To minimize the adverse impact of the domain boundaries, large high-quality single-crystal graphene films are highly desirable for most applications. To this end, two possible approaches involving the control over the nucleation and growth of graphene during the CVD process are proposed to achieve large