Uniform hexagonal graphene flakes and films grown on liquid copper surface.

Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 04/2012; 109(21):7992-6. DOI: 10.1073/pnas.1200339109
Source: PubMed

ABSTRACT Unresolved problems associated with the production of graphene materials include the need for greater control over layer number, crystallinity, size, edge structure and spatial orientation, and a better understanding of the underlying mechanisms. Here we report a chemical vapor deposition approach that allows the direct synthesis of uniform single-layered, large-size (up to 10,000 μm(2)), spatially self-aligned, and single-crystalline hexagonal graphene flakes (HGFs) and their continuous films on liquid Cu surfaces. Employing a liquid Cu surface completely eliminates the grain boundaries in solid polycrystalline Cu, resulting in a uniform nucleation distribution and low graphene nucleation density, but also enables self-assembly of HGFs into compact and ordered structures. These HGFs show an average two-dimensional resistivity of 609 ± 200 Ω and saturation current density of 0.96 ± 0.15 mA/μm, demonstrating their good conductivity and capability for carrying high current density.

  • [Show abstract] [Hide abstract]
    ABSTRACT: In the past decade, graphene and graphene-like 2D materials have drawn more and more attention in both academia and industry due to their fascinating properties. As an atomically thin 2D layered material, graphene has extremely high environmental susceptibility, that is, its properties are strongly affected by its surroundings. In this review, the current status and progress in graphene interface engineering are systematically discussed, including the interface between graphene (carbon sources) and an underlying growth substrate (catalyst), the interface between graphene and a supporting layer during a transfer process, as well as the interface between graphene and a modified substrate from the viewpoint of device applications. These key techniques involved in graphene synthesis, transfer, and device substrates can be further applied to other related 2D layered materials such as MoS2. Moreover, by combining 2D crystals in one particular stack, 2D-based heterostructures with desired functionalities can be achieved, which opens up a new avenue for the future applications of 2D layered materials.
    Small 08/2014; · 7.82 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Grain boundaries (GBs) in graphene prepared by chemical vapor deposition (CVD) greatly degrade the electrical and mechanical properties of graphene and thus hinder the applications of graphene in electronic devices. The seamless stitching of graphene flakes can avoid GBs, wherein the identical orientation of graphene domain is required. In this letter, the graphene orientation on one of the most used catalyst surface - Cu(100) surface, is explored by density functional theory (DFT) calculations. Our calculation demonstrates that a zigzag edged hexagonal graphene domain on a Cu(100) surface has two equivalent energetically preferred orientations, which are 30 degree away from each other. Therefore, the fusion of graphene domains on Cu(100) surface during CVD growth will inevitably lead to densely distributed GBs in the synthesized graphene. Aiming to solve this problem, a simple route, that applies external strain to break the symmetry of the Cu(100) surface, was proposed and proved efficient.
    Scientific reports. 01/2014; 4:6541.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Here we report a three-step growth method for high-quality mono-layer, bi-layer and tri-layer graphene with coverage ∼90% at atmospheric pressure. The growth temperature and gas flow rate have been found to be the key factors. This method would be of great importance for the large scale production of graphene with defined thickness.
    Chemical Communications 08/2014; · 6.38 Impact Factor


Available from