Temperature Dependence of the Reconstruction of Zigzag Edges in Graphene

He, Kui; Robertson, Alex W.; Fan, Ye; Allen, Christopher S.; Lin, Yung‐Chang; Suenaga, Kazu; Kirkland, Angus I.; Warner, Jamie H.

doi:10.1021/acsnano.5b01130

Cited by 72 publications

(87 citation statements)

References 43 publications

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“…5a), especially at a high temperature (above 600°C). 41,42 This reconstructed ZZ57 structure is theoretically considered to be the most stable edge of graphene. [43][44][45] Nevertheless, these ZZ57 edges would lead to the loss of the edge states magnetism.…”

Section: Discussionmentioning

confidence: 97%

Magnetism of graphene quantum dots

et al. 2017

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Graphene quantum dots with the high edge-to-area ratio have possibly substantial spin polarized edge states, which theoretically can generate fascinating magnetic properties. The magnetism of well-defined graphene quantum dots is relevant with both fundamental physics and potential applications in spintronics. In this article, we report the intrinsic magnetism of graphene quantum dots. Our graphene quantum dots with the average diameter of ca. 2.04 nm show the purely Curie-like paramagnetism with the local moment of 1.2 μ B at 2 K. It is proposed that the magnetic moment of graphene quantum dots may mainly origin from the residual zigzag edges passivated by hydroxyl groups. The ratio of nonmagnetic graphene quantum dots is approximately 6/7, with most of the magnetic edge states suppressed by edge defects and/or edge reconstruction arising from the high-temperature annealing. Our study experimentally unveils the intrinsic magnetism of graphene quantum dots.

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Section: Discussionmentioning

confidence: 97%

Magnetism of graphene quantum dots

et al. 2017

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“…In principle, both sp 2 and sp 3 terminations can be formed at the edges of zGNRs during the process of edge-saturations with hydrogen atoms in experiments [21][22][23]. Careful computational studies of hydrogen terminated ribbons [20,24] have demonstrated that the H2-terminated zGNRs (H2-zGNRs), with sp 3 edges, are more stable than the H-terminated zGNRs (H-zGNRs), with sp 2 edges.…”

Section: Introductionmentioning

confidence: 99%

Conductance gap induced by orbital symmetry mismatch in inhomogeneous hydrogen-terminated zigzag graphene nanoribbons

Chen

Wang

Zhang

et al. 2015

Organic Electronics

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“…Because the edge configuration of graphene are known to have significant influences to the electromagnetic property of graphene (Nakada et al, 1996;Son et al, 2006;Kim & Kim, 2008;Jung & MacDonald, 2009;Magda et al, 2014), the edge configuration and its stableness become one of major interests in studies of graphene hole defect. Direct atomic imaging at the graphene edges using aberration-corrected TEM gave the insight on the stability of edge configurations (Girit et al, 2009;Song et al, 2011;Kim et al, 2013a;He et al, 2015). Recently, He et al (2015) reported the temperature dependence of graphene edge configuration through in situ heating experiment using aberration-corrected TEM.…”

Section: Introductionmentioning

confidence: 99%

“…edges using aberration-corrected TEM gave the insight on the stability of edge configurations (Girit et al, 2009;Song et al, 2011;Kim et al, 2013a;He et al, 2015). Recently, He et al (2015) reported the temperature dependence of graphene edge configuration through in situ heating experiment using aberration-corrected TEM.…”

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Hole Defects on Two-Dimensional Materials Formed by Electron Beam Irradiation: Toward Nanopore Devices

Park

Ryu

Lee

2015

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Two-dimensional (2D) materials containing hole defects are a promising substitute for conventional nanopore membranes like silicon nitride. Hole defects on 2D materials, as atomically thin nanopores, have been used in nanopore devices, such as DNA sensor, gas sensor and purifier at lab-scale. For practical applications of 2D materials to nanopore devices, researches on characteristics of hole defects on graphene, hexagonal boron nitride and molybdenum disulfide have been conducted precisely using transmission electron microscope. Here, we summarized formation, features, structural preference and stability of hole defects on 2D materials with atomic-resolution transmission electron microscope images and theoretical calculations, emphasizing the future challenges in controlling the edge structures and stabilization of hole defects. Exploring the properties at the local structure of hole defects through in situ experiments is also the important issue for the fabrication of realistic 2D nanopore devices.Key Words: Two-dimensional materials, Hole defect, Nanopore, Transmission electron microscope, Defect structure Park HJ et al. 108consists of mono element of carbon, but hBN contains two elements of boron (B) and nitrogen (N) alternatively in plane, and each molybdenum and sulfur in MoS 2 are bound to each other with a ratio of 1:2 in a trigonal prism unit cell wherein Mo layer is sandwiched between sulfur layers (Fig. 1). Each material has its own composition, thus, it shows all different features such as formation process, edge structure, stability and consequential properties of hole defects on graphene, hBN, and MoS 2 , which are described below. Among various methods to make holes on 2D materials (Bieri et al., 2009; Girit et al., 2009; Bai et al., 2010;Kim et al., 2010;Koenig et al., 2012;Russo & Golovchenko, 2012), electron beam in transmission electron microscope (TEM) is good at size control at atomic scale, which is the most important issue for the sensitivity and selectivity of nanopore devices. If electron beam irradiation on a 2D specimen with a high electron energy breaks the atomic bonds within the material, which is called knock-on voltage, atoms are ejected from the lattice leaving holes on the materials. The atom displacement, knock-on thresholds and other structural information of graphene (Smith & Luzzi, 2001), hBN (Kotakoski et al., 2010), and MoS 2 (Komsa et al., 2012) are summarized in Table 1. Fig. 2A shows the hole defects of graphene by the electron beam irradiation at 80 kV. To make hole defects in graphene, over 86 kV of electron beam energy, the knock-on threshold voltage of graphene, needs to be irradiated on the sample. But some studies showed the existence of oxygen or other chemicals on the sheet or inside TEM chamber can lower the knock-on threshold of graphene by chemical etching effect . Inherent defects created from the synthesizing process of graphene also lower the knockon threshold voltage (Crespi et al., 1996). Once a vacancy is formed, it continuously grows as electron beam ...

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Temperature Dependence of the Reconstruction of Zigzag Edges in Graphene

Cited by 72 publications

References 43 publications

Magnetism of graphene quantum dots

Magnetism of graphene quantum dots

Conductance gap induced by orbital symmetry mismatch in inhomogeneous hydrogen-terminated zigzag graphene nanoribbons

Hole Defects on Two-Dimensional Materials Formed by Electron Beam Irradiation: Toward Nanopore Devices

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