1
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Luo X, Liang G, Li Y, Yu F, Zhao X. Regulating the Electronic Structure of Freestanding Graphene on SiC by Ge/Sn Intercalation: A Theoretical Study. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27249004. [PMID: 36558135 PMCID: PMC9788586 DOI: 10.3390/molecules27249004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 11/29/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022]
Abstract
The intrinsic n-type of epitaxial graphene on SiC substrate limits its applications in microelectronic devices, and it is thus vital to modulate and achieve p-type and charge-neutral graphene. The main groups of metal intercalations, such as Ge and Sn, are found to be excellent candidates to achieve this goal based on the first-principle calculation results. They can modulate the conduction type of graphene via intercalation coverages and bring out interesting magnetic properties to the entire intercalation structures without inducing magnetism to graphene, which is superior to the transition metal intercalations, such as Fe and Mn. It is found that the Ge intercalation leads to ambipolar doping of graphene, and the p-type graphene can only be obtained when forming the Ge adatom between Ge layer and graphene. Charge-neutral graphene can be achieved under high Sn intercalation coverage (7/8 bilayer) owing to the significantly increased distance between graphene and deformed Sn intercalation. These findings would open up an avenue for developing novel graphene-based spintronic and electric devices on SiC substrate.
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Affiliation(s)
- Xingyun Luo
- State Key Lab of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100, China
| | - Guojun Liang
- State Key Lab of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100, China
| | - Yanlu Li
- State Key Lab of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100, China
- Correspondence: (Y.L.); (X.Z.)
| | - Fapeng Yu
- State Key Lab of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100, China
| | - Xian Zhao
- Center for Optics Research and Engineering of Shandong University, Shandong University, Qingdao 266237, China
- Correspondence: (Y.L.); (X.Z.)
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2
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Nieman R, Aquino AJA, Lischka H. Exploration of Graphene Defect Reactivity toward a Hydrogen Radical Utilizing a Preactivated Circumcoronene Model. J Phys Chem A 2021; 125:1152-1165. [PMID: 33507752 DOI: 10.1021/acs.jpca.0c09255] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A preexisting chemisorbed defect is well-known to increase the reactivity of graphene which is normally chemically inert. Specifically, the presence of chemisorbed hydrogen atoms forming an sp3-hybridized C-H bond is known to increase the reactivity of neighboring carbon atoms toward additional hydrogenation with wide-ranging applications from materials science to astrochemistry. In this work, static DFT and DFT-based direct dynamics simulations are used to characterize the reactivity of a graphene sheet around an existing C-H bond defect. The spin density landscape shows how to guide subsequent H atom additions, always bonding most strongly to the carbon atom with greatest spin density. Molecular dynamics of an impinging H atom under thermal conditions with defect graphene was used to determine the statistics of probable reactions. The most frequent outcome is inelastic scattering (48%) and then Eley-Rideal (ER) abstraction of the chemisorbed H atom as vibrationally hot H2 (40%), while the least likely, but probably most interesting, result is formation of a novel C-H bond (12%). The C-H bonds always form in the β sublattice. The carbon atom in the para position shows to be most reactive toward the incoming H atom, followed by the ortho carbon, in agreement with the spin density computed in the static calculations. Globally, the graphene energy surface is repulsive, but the defects create local channels into this energy surface through which reactants can move locally through and react with the activated surface without a barrier.
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Affiliation(s)
- Reed Nieman
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States.,Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Adelia J A Aquino
- Department of Mechanical Engineering, Texas Tech University, Lubbock, Texas 79409, United States.,School of Pharmaceutical Sciences and Technology, Tianjin University, Tianjin 300072, P. R. China
| | - Hans Lischka
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States.,School of Pharmaceutical Sciences and Technology, Tianjin University, Tianjin 300072, P. R. China
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3
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Uemura S, Vantasin S, Kitahama Y, Tanaka YY, Suzuki T, Doujima D, Kaneko T, Ozaki Y. Interactions Between Epitaxial Graphene Grown on the Si- and C-Faces of 4H-SiC Investigated Using Raman Imaging and Tip-Enhanced Raman Scattering. APPLIED SPECTROSCOPY 2020; 74:1384-1390. [PMID: 32627577 DOI: 10.1177/0003702820944247] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Interactions between epitaxial graphene grown on Si- and C-faces were investigated using Raman imaging and tip-enhanced Raman scattering (TERS). In the TERS spectrum, which has a spatial resolution exceeding the diffraction limit, a D band was observed not from graphene surface, but from the edges of the epitaxial graphene ribbons without a buffer layer, which interacts with SiC on the Si-face. In contrast, for a graphene micro-island on the C-face, the D band disappeared even on the edges where the C atoms were arranged in armchair configurations. The disappearance of the edge chirality via combination between the C atoms and SiC on the C-face is responsible for this phenomenon. The TERS signals from the C-face were weaker than those from the Si-face without the buffer layer. On the Si-face with a buffer layer, the graphene TERS signal was hardly observed. TERS enhancement was suppressed by interactions on the edges or by the buffer layer between the SiC and graphene on the C- or Si-face, respectively.
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Affiliation(s)
- Shohei Uemura
- School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo, Japan
| | - Sanpon Vantasin
- School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo, Japan
| | - Yasutaka Kitahama
- School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo, Japan
| | | | | | - Daichi Doujima
- School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo, Japan
| | - Tadaaki Kaneko
- School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo, Japan
| | - Yukihiro Ozaki
- School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo, Japan
- 226492Toyota Physical and Chemical Research Institute, Nagakute, Japan
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4
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Lim H, Park Y, Lee M, Ahn JG, Li BW, Luo D, Jung J, Ruoff RS, Kim Y. Centimeter-Scale and Highly Crystalline Two-Dimensional Alcohol: Evidence for Graphenol (C 6OH). NANO LETTERS 2020; 20:2107-2112. [PMID: 32053385 DOI: 10.1021/acs.nanolett.0c00103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report a chemical route to synthesize centimeter-scale stoichiometric "graphenol (C6OH1)", a 2D crystalline alcohol, via vapor phase hydroxylation of epitaxial graphene on Cu(111). Atomic resolution scanning tunneling microscopy revealed this highly-ordered configuration of graphenol and low energy electron diffraction studies on a large-area single crystal graphene film demonstrated the feasibility of the same superstructure being achieved at the centimeter length scale. Periodic density functional theory (DFT) calculations about the formation of C6(OH)1 and its electronic structure are also reported.
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Affiliation(s)
- Hyunseob Lim
- Department of Chemistry, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
- Surface and Interface Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Younghee Park
- Department of Chemistry, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Minhui Lee
- Surface and Interface Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Department of Chemistry, University of Ulsan, Ulsan 44776, Republic of Korea
| | - Jong-Guk Ahn
- Department of Chemistry, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Bao Wen Li
- Center for Multidimensional Carbon Materials, Institute of Basic Science, UNIST-gil 50, Ulsan 689-798, Republic of Korea
| | - Da Luo
- Center for Multidimensional Carbon Materials, Institute of Basic Science, UNIST-gil 50, Ulsan 689-798, Republic of Korea
| | - Jaehoon Jung
- Surface and Interface Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Department of Chemistry, University of Ulsan, Ulsan 44776, Republic of Korea
| | - Rodney S Ruoff
- Center for Multidimensional Carbon Materials, Institute of Basic Science, UNIST-gil 50, Ulsan 689-798, Republic of Korea
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan 689-798, Republic of Korea
| | - Yousoo Kim
- Surface and Interface Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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5
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Yuan G, Lin D, Wang Y, Huang X, Chen W, Xie X, Zong J, Yuan QQ, Zheng H, Wang D, Xu J, Li SC, Zhang Y, Sun J, Xi X, Gao L. Proton-assisted growth of ultra-flat graphene films. Nature 2020; 577:204-208. [DOI: 10.1038/s41586-019-1870-3] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 09/30/2019] [Indexed: 11/09/2022]
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6
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Mazza AR, Miettinen A, Daykin AA, He X, Charlton TR, Conrad M, Guha S, Lu Q, Bian G, Conrad EH, Miceli PF. Revealing interfacial disorder at the growth-front of thick many-layer epitaxial graphene on SiC: a complementary neutron and X-ray scattering investigation. NANOSCALE 2019; 11:14434-14445. [PMID: 31334737 DOI: 10.1039/c9nr03504d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Epitaxial graphene on SiC provides both an excellent source of high-quality graphene as well as an architecture to support its application. Although single-layer graphene on Si-face SiC has garnered extensive interest, many-layer graphene produced on C-face SiC could be significantly more robust for enabling applications. Little is known, however, about the structural properties related to the growth evolution at the buried interface for thick many-layer graphene. Using complementary X-ray scattering and neutron reflectivity as well as electron microscopy, we demonstrate that thick many-layer epitaxial graphene exhibits two vastly different length-scales of the buried interface roughness as a consequence of the Si sublimation that produces the graphene. Over long lateral length-scales the roughness is extremely large (hundreds of Å) and it varies proportionally to the number of graphene layers. In contrast, over much shorter lateral length-scales we observe an atomically abrupt interface with SiC terraces. Graphene near the buried interface exhibits a slightly expanded interlayer spacing (∼1%) and fluctuations of this spacing, indicating a tendency for disorder near the growth front. Nevertheless, Dirac cones are observed from the graphene while its domain size routinely reaches micron length-scales, indicating the persistence of high-quality graphene beginning just a short distance away from the buried interface. Discovering and reconciling the different length-scales of roughness by reflectivity was complicated by strong diffuse scattering and we provide a detailed discussion of how these difficulties were resolved. The insight from this analysis will be useful for other highly rough interfaces among broad classes of thin-film materials.
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Affiliation(s)
- A R Mazza
- Department of Physics and Astronomy, University of Missouri, Columbia, Missouri, USA.
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7
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Feng Y, Chen J, Fang W, Wang EG, Michaelides A, Li XZ. Hydrogenation Facilitates Proton Transfer through Two-Dimensional Honeycomb Crystals. J Phys Chem Lett 2017; 8:6009-6014. [PMID: 29185752 DOI: 10.1021/acs.jpclett.7b02820] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Recent experiments have triggered a debate about the ability of protons to transfer easily through individual layers of graphene and hexagonal boron nitride (h-BN). However, state-of-the-art computer calculations have shown that the barriers to proton penetration can, at >3 eV, be excessively high. Despite considerable interest the origin of this apparent anomaly between experiment and simulation remains unclear. We offer a new perspective on this debate and show on the basis of first-principles calculations that the barrier for proton penetration is significantly reduced, to <1 eV, upon hydrogenation, even in the absence of pinholes in the lattice. Although hydrogenation has not been offered as an explanation before, analysis reveals that the barrier is reduced because hydrogenation destabilizes the initial state (a deep-lying chemisorption state) and expands the honeycomb lattice through which the protons penetrate. This study offers a rationalization of the fast proton transfer observed in experiments and highlights the ability of proton transport through single-layer materials in hydrogen-rich solutions.
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Affiliation(s)
- Yexin Feng
- School of Physics and Electronics, Hunan University , Changsha 410082, P. R. China
| | - Ji Chen
- Thomas Young Centre, University College London , London WC1E 6BT, United Kingdom
- London Centre for Nanotechnology, University College London , London WC1E 6BT, United Kingdom
- Department of Physics and Astronomy, University College London , London WC1E 6BT, United Kingdom
| | - Wei Fang
- Thomas Young Centre, University College London , London WC1E 6BT, United Kingdom
- London Centre for Nanotechnology, University College London , London WC1E 6BT, United Kingdom
- Department of Chemistry, University College London , London WC1E 6BT, United Kingdom
| | - En-Ge Wang
- School of Physics, ICQM, and Collaborative Innovation Center of Quantum Matter, Peking University , Beijing 100871, P. R. China
| | - Angelos Michaelides
- Thomas Young Centre, University College London , London WC1E 6BT, United Kingdom
- London Centre for Nanotechnology, University College London , London WC1E 6BT, United Kingdom
- Department of Physics and Astronomy, University College London , London WC1E 6BT, United Kingdom
| | - Xin-Zheng Li
- School of Physics, ICQM, and Collaborative Innovation Center of Quantum Matter, Peking University , Beijing 100871, P. R. China
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8
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Liu K, Yan P, Li J, He C, Ouyang T, Zhang C, Tang C, Zhong J. Effect of hydrogen passivation on the decoupling of graphene on SiC(0001) substrate: First-principles calculations. Sci Rep 2017; 7:8461. [PMID: 28814766 PMCID: PMC5559521 DOI: 10.1038/s41598-017-09161-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 07/21/2017] [Indexed: 11/09/2022] Open
Abstract
Intercalation of hydrogen is important for understanding the decoupling of graphene from SiC(0001) substrate. Employing first-principles calculations, we have systematically studied the decoupling of graphene from SiC surface by H atoms intercalation from graphene boundary. It is found the passivation of H atoms on both graphene edge and SiC substrate is the key factor of the decoupling process. Passivation of graphene edge can weaken the interaction between graphene boundary and the substrate, which reduced the energy barrier significantly for H diffusion into the graphene-SiC interface. As more and more H atoms diffuse into the interface and saturate the Si dangling bonds around the boundary, graphene will detach from substrate. Furthermore, the energy barriers in these processes are relatively low, indicating that these processes can occur under the experimental temperature.
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Affiliation(s)
- Kang Liu
- Hunan Key Laboratory of Micro-Nano Energy Materials and Devices, Xiangtan University, Hunan, 411105, P. R. China.,Laboratory for Quantum Engineering and Micro-Nano Energy Technology and School of Physics and Optoelectronics, Xiangtan University, Hunan, 411105, P. R. China
| | - Pinglan Yan
- Hunan Key Laboratory of Micro-Nano Energy Materials and Devices, Xiangtan University, Hunan, 411105, P. R. China.,Laboratory for Quantum Engineering and Micro-Nano Energy Technology and School of Physics and Optoelectronics, Xiangtan University, Hunan, 411105, P. R. China
| | - Jin Li
- Hunan Key Laboratory of Micro-Nano Energy Materials and Devices, Xiangtan University, Hunan, 411105, P. R. China. .,Laboratory for Quantum Engineering and Micro-Nano Energy Technology and School of Physics and Optoelectronics, Xiangtan University, Hunan, 411105, P. R. China.
| | - Chaoyu He
- Hunan Key Laboratory of Micro-Nano Energy Materials and Devices, Xiangtan University, Hunan, 411105, P. R. China.,Laboratory for Quantum Engineering and Micro-Nano Energy Technology and School of Physics and Optoelectronics, Xiangtan University, Hunan, 411105, P. R. China
| | - Tao Ouyang
- Hunan Key Laboratory of Micro-Nano Energy Materials and Devices, Xiangtan University, Hunan, 411105, P. R. China.,Laboratory for Quantum Engineering and Micro-Nano Energy Technology and School of Physics and Optoelectronics, Xiangtan University, Hunan, 411105, P. R. China
| | - Chunxiao Zhang
- Hunan Key Laboratory of Micro-Nano Energy Materials and Devices, Xiangtan University, Hunan, 411105, P. R. China.,Laboratory for Quantum Engineering and Micro-Nano Energy Technology and School of Physics and Optoelectronics, Xiangtan University, Hunan, 411105, P. R. China
| | - Chao Tang
- Hunan Key Laboratory of Micro-Nano Energy Materials and Devices, Xiangtan University, Hunan, 411105, P. R. China. .,Laboratory for Quantum Engineering and Micro-Nano Energy Technology and School of Physics and Optoelectronics, Xiangtan University, Hunan, 411105, P. R. China.
| | - Jianxin Zhong
- Hunan Key Laboratory of Micro-Nano Energy Materials and Devices, Xiangtan University, Hunan, 411105, P. R. China.,Laboratory for Quantum Engineering and Micro-Nano Energy Technology and School of Physics and Optoelectronics, Xiangtan University, Hunan, 411105, P. R. China
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9
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Nieman R, Das A, Aquino AJ, Amorim RG, Machado FB, Lischka H. Single and double carbon vacancies in pyrene as first models for graphene defects: A survey of the chemical reactivity toward hydrogen. Chem Phys 2017. [DOI: 10.1016/j.chemphys.2016.08.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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10
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Gao L, Pal PP, Seideman T, Guisinger NP, Guest JR. Current-Driven Hydrogen Desorption from Graphene: Experiment and Theory. J Phys Chem Lett 2016; 7:486-494. [PMID: 26787160 DOI: 10.1021/acs.jpclett.5b02471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Electron-stimulated desorption of hydrogen from the graphene/SiC(0001) surface at room temperature was investigated with ultrahigh vacuum scanning tunneling microscopy and ab initio calculations in order to elucidate the desorption mechanisms and pathways. Two different desorption processes were observed. In the high electron energy regime (4-8 eV), the desorption yield is independent of both voltage and current, which is attributed to the direct electronic excitation of the C-H bond. In the low electron energy regime (2-4 eV), however, the desorption yield exhibits a threshold dependence on voltage, which is explained by the vibrational excitation of the C-H bond via transient ionization induced by inelastic tunneling electrons. The observed current independence of the desorption yield suggests that the vibrational excitation is a single-electron process. We also observed that the curvature of graphene dramatically affects hydrogen desorption. Desorption from concave regions was measured to be much more probable than desorption from convex regions in the low electron energy regime (∼2 eV), as would be expected from the identified desorption mechanism.
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Affiliation(s)
- Li Gao
- Department of Physics and Astronomy, California State University , Northridge, California 91330, United States
- Center for Nanoscale Materials, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Partha Pratim Pal
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Tamar Seideman
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Nathan P Guisinger
- Center for Nanoscale Materials, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Jeffrey R Guest
- Center for Nanoscale Materials, Argonne National Laboratory , Argonne, Illinois 60439, United States
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11
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Vantasin S, Tanaka Y, Uemura S, Suzuki T, Kutsuma Y, Doujima D, Kaneko T, Ozaki Y. Characterization of SiC-grown epitaxial graphene microislands using tip-enhanced Raman spectroscopy. Phys Chem Chem Phys 2016; 17:28993-9. [PMID: 26456383 DOI: 10.1039/c5cp05014f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Single-layer graphene microislands with smooth edges and no visible grain boundary were epitaxially grown on the C-face of 4H-SiC and then characterized at the nanoscale using tip-enhanced Raman spectroscopy (TERS). Although these graphene islands appear highly homogeneous in micro-Raman imaging, TERS reveals the nanoscale strain variation caused by ridge nanostructures. A G' band position shift up to 9 cm(-1) and a band broadening up to 30 cm(-1) are found in TERS spectra obtained from nanoridges, which is explained by the compressive strain relaxation mechanism. The small size and refined nature of the graphene islands help in minimizing the inhomogeneity caused by macroscale factors, and allow a comparative discussion of proposed mechanisms of nanoridge formation.
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Affiliation(s)
- Sanpon Vantasin
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan.
| | - Yoshito Tanaka
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
| | - Shohei Uemura
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan.
| | - Toshiaki Suzuki
- UNISOKU Co. Ltd, 2-4-3 Kasugano, Hirakata, Osaka 573-0131, Japan
| | - Yasunori Kutsuma
- Department of Physics, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Daichi Doujima
- Department of Physics, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Tadaaki Kaneko
- Department of Physics, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Yukihiro Ozaki
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan.
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12
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Criado A, Melchionna M, Marchesan S, Prato M. Kovalente Funktionalisierung von Graphen auf Substraten. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201501473] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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13
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Criado A, Melchionna M, Marchesan S, Prato M. The Covalent Functionalization of Graphene on Substrates. Angew Chem Int Ed Engl 2015; 54:10734-50. [PMID: 26242633 DOI: 10.1002/anie.201501473] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Indexed: 01/10/2023]
Abstract
The utilization of grown or deposited graphene on solid substrates offers key benefits for functionalization processes, but especially to attain structures with a high level of control for electronics and "smart" materials. In this review, we will initially focus on the nature and properties of graphene on substrates, based on the method of preparation. We will then analyze the most relevant literature on the functionalization of graphene on substrates. In particular, we will comparatively discuss radical reactions, cycloadditions, halogenations, hydrogenations, and oxidations. We will especially address the question of how the reactivity of graphene is affected by its morphology (i.e., number of layers, defects, substrate, curvature, etc.).
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Affiliation(s)
- Alejandro Criado
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Piazzale Europa 1, 34127 Trieste (Italy).
| | - Michele Melchionna
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Piazzale Europa 1, 34127 Trieste (Italy)
| | - Silvia Marchesan
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Piazzale Europa 1, 34127 Trieste (Italy)
| | - Maurizio Prato
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Piazzale Europa 1, 34127 Trieste (Italy).
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14
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Abdelkader AM, Patten HV, Li Z, Chen Y, Kinloch IA. Electrochemical exfoliation of graphite in quaternary ammonium-based deep eutectic solvents: a route for the mass production of graphane. NANOSCALE 2015; 7:11386-92. [PMID: 26074262 DOI: 10.1039/c5nr02840j] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We demonstrate a facile and scalable electrochemical approach to exfoliate graphite, which permits in situ hydrogenation of the resultant graphene via a solvated NR(4+) graphite compound in quaternary ammonium-based deep eutectic solvents. Spectroscopic studies reveal the presence of sp(3) C-H bonds in the hydrogenated graphene. The resulting materials consist of micrometre-sized and predominantly monolayer to few layers thick hydrogenated graphenic flakes. A large band gap (∼4 eV) further establishes the high level of hydrogenation. It is also possible to tune the band gap introduced to the graphene by controlling the level of hydrogenation. The mechanism of the exfoliation and hydrogenation is also discussed.
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Affiliation(s)
- Amr M Abdelkader
- School of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
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15
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Ferrari AC, Bonaccorso F, Fal'ko V, Novoselov KS, Roche S, Bøggild P, Borini S, Koppens FHL, Palermo V, Pugno N, Garrido JA, Sordan R, Bianco A, Ballerini L, Prato M, Lidorikis E, Kivioja J, Marinelli C, Ryhänen T, Morpurgo A, Coleman JN, Nicolosi V, Colombo L, Fert A, Garcia-Hernandez M, Bachtold A, Schneider GF, Guinea F, Dekker C, Barbone M, Sun Z, Galiotis C, Grigorenko AN, Konstantatos G, Kis A, Katsnelson M, Vandersypen L, Loiseau A, Morandi V, Neumaier D, Treossi E, Pellegrini V, Polini M, Tredicucci A, Williams GM, Hong BH, Ahn JH, Kim JM, Zirath H, van Wees BJ, van der Zant H, Occhipinti L, Di Matteo A, Kinloch IA, Seyller T, Quesnel E, Feng X, Teo K, Rupesinghe N, Hakonen P, Neil SRT, Tannock Q, Löfwander T, Kinaret J. Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems. NANOSCALE 2015; 7:4598-810. [PMID: 25707682 DOI: 10.1039/c4nr01600a] [Citation(s) in RCA: 985] [Impact Index Per Article: 109.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.
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Affiliation(s)
- Andrea C Ferrari
- Cambridge Graphene Centre, University of Cambridge, Cambridge, CB3 0FA, UK.
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16
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Sahin H, Leenaerts O, Singh SK, Peeters FM. Graphane. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2015. [DOI: 10.1002/wcms.1216] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- H. Sahin
- Department of Physics; University of Antwerp, Groenenborgerlaan 171, BE-2020; Antwerp Belgium
| | - O. Leenaerts
- Department of Physics; University of Antwerp, Groenenborgerlaan 171, BE-2020; Antwerp Belgium
| | - S. K. Singh
- Department of Physics; University of Antwerp, Groenenborgerlaan 171, BE-2020; Antwerp Belgium
| | - F. M. Peeters
- Department of Physics; University of Antwerp, Groenenborgerlaan 171, BE-2020; Antwerp Belgium
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17
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Lin C, Feng Y, Xiao Y, Dürr M, Huang X, Xu X, Zhao R, Wang E, Li XZ, Hu Z. Direct observation of ordered configurations of hydrogen adatoms on graphene. NANO LETTERS 2015; 15:903-908. [PMID: 25621539 DOI: 10.1021/nl503635x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Ordered configurations of hydrogen adatoms on graphene have long been proposed, calculated, and searched for. Here, we report direct observation of several ordered configurations of H adatoms on graphene by scanning tunneling microscopy. On the top side of the graphene plane, H atoms in the configurations appear to stick to carbon atoms in the same sublattice. Scanning tunneling spectroscopy measurements revealed a substantial gap in the local density of states in H-contained regions as well as in-gap states below the conduction band due to the incompleteness of H ordering. These findings can be well explained by density functional theory calculations based on double-sided H configurations. In addition, factors that may influence H ordering are discussed.
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Affiliation(s)
- Chenfang Lin
- State Key Lab for Mesoscopic Physics, School of Physics, Peking University , Beijing 100871, China
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18
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Abstract
This perspective outlines the chemistry of graphene, including functionalization, doping, photochemistry, catalytic chemistry and supramolecular chemistry.
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Affiliation(s)
- Xiluan Wang
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- People's Republic of China
- Beijing Key Laboratory of Lignocellulosic Chemistry
| | - Gaoquan Shi
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- People's Republic of China
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19
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Merino P, Švec M, Martínez JI, Mutombo P, Gonzalez C, Martín-Gago JA, de Andres PL, Jelinek P. Ortho and para hydrogen dimers on G/SiC(0001): combined STM and DFT study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 31:233-239. [PMID: 25486105 DOI: 10.1021/la504021x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The hydrogen (H) dimer structures formed upon room-temperature H adsorption on single layer graphene (SLG) grown on SiC(0001) are addressed using a combined theoretical-experimental approach. Our study includes density functional theory (DFT) calculations for the full (6√3 × 6√3)R30° unit cell of the SLG/SiC(0001) substrate and atomically resolved scanning tunneling microscopy images determining simultaneously the graphene lattice and the internal structure of the H adsorbates. We show that H atoms normally group in chemisorbed coupled structures of different sizes and orientations. We make an atomic scale determination of the most stable experimental geometries, the small dimers and ellipsoid-shaped features, and we assign them to hydrogen adsorbed in para dimers and ortho dimers configuration, respectively, through comparison with the theory.
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Affiliation(s)
- P Merino
- Centro de Astrobiología INTA-CSIC, Carretera de Ajalvir, km. 4, ES-28850 Madrid, Spain
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20
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Martínez JI, Martín-Gago JA, Cernicharo J, de Andres PL. Etching of graphene in a Hydrogen-rich Atmosphere towards the Formation of Hydrocarbons in Circumstellar Clouds. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2014; 118:26882-26886. [PMID: 26709358 PMCID: PMC4688951 DOI: 10.1021/jp509195d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We describe a mechanism that explains the formation of hydrocarbons and hydrocarbyls from hydrogenated graphene/graphite; hard C-C bonds are weakened and broken by the synergistic effect of chemisorbed hydrogen and high temperature vibrations. Total energies, optimized structures, and transition states are obtained from Density Functional Theory simulations. These values have been used to determine the Boltzman probability for a thermal fluctuation to overcome the kinetic barriers, yielding the time scale for an event to occur. This mechanism can be used to rationalize the possible routes for the creation of small hydrocarbons and hydrocarbyls from etched graphene/graphite in stellar regions.
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Affiliation(s)
- José I. Martínez
- To whom correspondence should be addressed: , Phone: +34 (91)3349000 ext. 366. Fax: +34 (91)3720623
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21
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A general and scalable synthesis approach to porous graphene. Nat Commun 2014; 5:4716. [DOI: 10.1038/ncomms5716] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2014] [Accepted: 07/17/2014] [Indexed: 01/27/2023] Open
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22
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Mondal T, Bhowmick AK, Krishnamoorti R. Stress generation and tailoring of electronic properties of expanded graphite by click chemistry. ACS APPLIED MATERIALS & INTERFACES 2014; 6:7244-7253. [PMID: 24812102 DOI: 10.1021/am500471q] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The generation of stress in expanded graphite (E-GPT) due to covalent attachment of bulky side groups connected via a hetero atom is reported. Specifically, E-GPT is modified at different levels of grafting using "click" chemistry to graft 1-ethynyl-4-fluoro benzene onto graphene sheets via a triazole ring. In the range of grafting densitites examined, Raman spectroscopy indicates that the stress generated in graphene is linearly dependent on the extent of grafting. The functionalized graphene platelets with 6% functionalization transform from semi-metal behavior of the pristine material to semi-conductor behavior and indicates the ability of functionalization to change optical and electronic properties of graphene platelets similar to the deposition of thin layers of top gate oxides onto graphene.
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Affiliation(s)
- Titash Mondal
- Department of Chemistry, Indian Institute of Technology Patna , Patna, Bihar 800013, India
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23
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Graphene supported graphone/graphane bilayer nanostructure material for spintronics. Sci Rep 2014; 4:3862. [PMID: 24457465 PMCID: PMC3900929 DOI: 10.1038/srep03862] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 01/06/2014] [Indexed: 11/18/2022] Open
Abstract
We report an investigation into the magnetic and electronic properties of partially hydrogenated vertically aligned few layers graphene (FLG) synthesized by microwave plasma enhanced chemical vapor deposition. The FLG samples are hydrogenated at different substrate temperatures to alter the degree of hydrogenation and their depth profile. The unique morphology of the structure gives rise to a unique geometry in which graphane/graphone is supported by graphene layers in the bulk, which is very different from other widely studied structures such as one-dimensional nanoribbons. Synchrotron based x-ray absorption fine structure spectroscopy measurements have been used to investigate the electronic structure and the underlying hydrogenation mechanism responsible for the magnetic properties. While ferromagnetic interactions seem to be predominant, the presence of antiferromagnetic interaction was also observed. Free spins available via the conversion of sp2 to sp3 hybridized structures, and the possibility of unpaired electrons from defects induced upon hydrogenation are thought to be likely mechanisms for the observed ferromagnetic orders.
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24
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Tang Q, Zhou Z, Chen Z. Graphene-related nanomaterials: tuning properties by functionalization. NANOSCALE 2013; 5:4541-83. [PMID: 23443470 DOI: 10.1039/c3nr33218g] [Citation(s) in RCA: 209] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
In this review, we discuss the most recent progress on graphene-related nanomaterials, including doped graphene and derived graphene nanoribbons, graphene oxide, graphane, fluorographene, graphyne, graphdiyne, and porous graphene, from both experimental and theoretical perspectives, and emphasize tuning their stability, electronic and magnetic properties by chemical functionalization.
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Affiliation(s)
- Qing Tang
- Tianjin Key Laboratory of Metal and Molecule Based Material Chemistry, Institute of New Energy Material Chemistry, Computational Centre for Molecule Science, Nankai University, Tianjin 300071, PR China
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25
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Abstract
Although graphene's physical structure is a single atom thick, two-dimensional, hexagonal crystal of sp(2) bonded carbon, this simple description belies the myriad interesting and complex physical properties attributed to this fascinating material. Because of its unusual electronic structure and superlative properties, graphene serves as a leading candidate for many next generation technologies including high frequency electronics, broadband photodetectors, biological and gas sensors, and transparent conductive coatings. Despite this promise, researchers could apply graphene more routinely in real-world technologies if they could chemically adjust graphene's electronic properties. For example, the covalent modification of graphene to create a band gap comparable to silicon (∼1 eV) would enable its use in digital electronics, and larger band gaps would provide new opportunities for graphene-based photonics. Toward this end, researchers have focused considerable effort on the chemical functionalization of graphene. Due to its high thermodynamic stability and chemical inertness, new methods and techniques are required to create covalent bonds without promoting undesirable side reactions or irreversible damage to the underlying carbon lattice. In this Account, we review and discuss recent theoretical and experimental work studying covalent modifications to graphene using gas phase atomic radicals. Atomic radicals have sufficient energy to overcome the kinetic and thermodynamic barriers associated with covalent reactions on the basal plane of graphene but lack the energy required to break the C-C sigma bonds that would destroy the carbon lattice. Furthermore, because they are atomic species, radicals substantially reduce the likelihood of unwanted side reactions that confound other covalent chemistries. Overall, these methods based on atomic radicals show promise for the homogeneous functionalization of graphene and the production of new classes of two-dimensional materials with fundamentally different electronic and physical properties. Specifically, we focus on recent studies of the addition of atomic hydrogen, fluorine, and oxygen to the basal plane of graphene. In each of these reactions, a high energy, activating step initiates the process, breaking the local π structure and distorting the surrounding lattice. Scanning tunneling microscopy experiments reveal that substrate mediated interactions often dominate when the initial binding event occurs. We then compare these substrate effects with the results of theoretical studies that typically assume a vacuum environment. As the surface coverage increases, clusters often form around the initial distortion, and the stoichiometric composition of the saturated end product depends strongly on both the substrate and reactant species. In addition to these chemical and structural observations, we review how covalent modification can extend the range of physical properties that are achievable in two-dimensional materials.
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Affiliation(s)
- James E. Johns
- Departments of Materials Science, Chemistry, and Medicine, Northwestern University, Evanston, Illinois 60208-3108, United States
| | - Mark C. Hersam
- Departments of Materials Science, Chemistry, and Medicine, Northwestern University, Evanston, Illinois 60208-3108, United States
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26
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Boukhvalov DW. DFT modeling of the covalent functionalization of graphene: from ideal to realistic models. RSC Adv 2013. [DOI: 10.1039/c3ra23372c] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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27
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Scheffler M, Haberer D, Petaccia L, Farjam M, Schlegel R, Baumann D, Hänke T, Grüneis A, Knupfer M, Hess C, Büchner B. Probing local hydrogen impurities in quasi-free-standing graphene. ACS NANO 2012; 6:10590-10597. [PMID: 23157662 DOI: 10.1021/nn303485c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report high-resolution scanning tunneling microscopy and spectroscopy of hydrogenated, quasi-free-standing graphene. For this material, theory has predicted the appearance of a midgap state at the Fermi level, and first angle-resolved photoemission spectroscopy (ARPES) studies have provided evidence for the existence of this state in the long-range electronic structure. However, the spatial extension of H defects, their preferential adsorption patterns on graphene, or local electronic structure are experimentally still largely unexplored. Here, we investigate the shapes and local electronic structure of H impurities that go with the aforementioned midgap state observed in ARPES. Our measurements of the local density of states at hydrogenated patches of graphene reveal a hydrogen impurity state near the Fermi level whose shape depends on the tip position with respect to the center of a patch. In the low H concentration regime, we further observe predominantly single hydrogenation sites as well as extended multiple C-H sites in parallel orientation to the lattice vectors, indicating an adsorption at the same graphene sublattice. This is corroborated by ARPES measurements showing the formation of a dispersionless hydrogen impurity state which is extended over the whole Brillouin zone.
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28
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Nilsson L, Andersen M, Balog R, Lægsgaard E, Hofmann P, Besenbacher F, Hammer B, Stensgaard I, Hornekær L. Graphene coatings: probing the limits of the one atom thick protection layer. ACS NANO 2012; 6:10258-10266. [PMID: 23106828 DOI: 10.1021/nn3040588] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The limitations of graphene as an effective corrosion-inhibiting coating on metal surfaces, here exemplified by the hex-reconstructed Pt(100) surface, are probed by scanning tunneling microscopy measurements and density functional theory calculations. While exposure of small molecules directly onto the Pt(100) surface will lift the reconstruction, a single graphene layer is observed to act as an effective coating, protecting the reactive surface from O(2) exposure and thus preserving the reconstruction underneath the graphene layer in O(2) pressures as high as 10(-4) mbar. A similar protective effect against CO is observed at CO pressures below 10(-6) mbar. However, at higher pressures CO is observed to intercalate under the graphene coating layer, thus lifting the reconstruction. The limitations of the coating effect are further tested by exposure to hot atomic hydrogen. While the coating can withstand these extreme conditions for a limited amount of time, after substantial exposure, the Pt(100) reconstruction is lifted. Annealing experiments and density functional theory calculations demonstrate that the basal plane of the graphene stays intact and point to a graphene-mediated mechanism for the H-induced lifting of the reconstruction.
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Affiliation(s)
- Louis Nilsson
- Department of Physics and Astronomy and Interdisciplinary Nanoscience Center iNANO, Aarhus University, DK-8000 Aarhus C, Denmark
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29
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Schäfer RA, Englert JM, Wehrfritz P, Bauer W, Hauke F, Seyller T, Hirsch A. On the Way to Graphane-Pronounced Fluorescence of Polyhydrogenated Graphene. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/anie.201206799] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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30
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Schäfer RA, Englert JM, Wehrfritz P, Bauer W, Hauke F, Seyller T, Hirsch A. Auf dem Weg zu Graphan - ausgeprägte Fluoreszenz von polyhydriertem Graphen. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201206799] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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31
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Abstract
Hydrogen-based fuel cells are promising solutions for the efficient and clean delivery of electricity. Since hydrogen is an energy carrier, a key step for the development of a reliable hydrogen-based technology requires solving the issue of storage and transport of hydrogen. Several proposals based on the design of advanced materials such as metal hydrides and carbon structures have been made to overcome the limitations of the conventional solution of compressing or liquefying hydrogen in tanks. Nevertheless none of these systems are currently offering the required performances in terms of hydrogen storage capacity and control of adsorption/desorption processes. Therefore the problem of hydrogen storage remains so far unsolved and it continues to represent a significant bottleneck to the advancement and proliferation of fuel cell and hydrogen technologies. Recently, however, several studies on graphene, the one-atom-thick membrane of carbon atoms packed in a honeycomb lattice, have highlighted the potentialities of this material for hydrogen storage and raise new hopes for the development of an efficient solid-state hydrogen storage device. Here we review on-going efforts and studies on functionalized and nanostructured graphene for hydrogen storage and suggest possible developments for efficient storage/release of hydrogen under ambient conditions.
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Affiliation(s)
- Valentina Tozzini
- NEST-Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy.
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32
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Deshpande A, Sham CH, Alaboson JMP, Mullin JM, Schatz GC, Hersam MC. Self-assembly and photopolymerization of sub-2 nm one-dimensional organic nanostructures on graphene. J Am Chem Soc 2012; 134:16759-64. [PMID: 22928587 DOI: 10.1021/ja307061e] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
While graphene has attracted significant attention from the research community due to its high charge carrier mobility, important issues remain unresolved that prevent its widespread use in technologically significant applications such as digital electronics. For example, the chemical inertness of graphene hinders integration with other materials, and the lack of a bandgap implies poor switching characteristics in transistors. The formation of ordered organic monolayers on graphene has the potential to address each of these challenges. In particular, functional groups incorporated into the constituent molecules enable tailored chemical reactivity, while molecular-scale ordering within the monolayer provides sub-2 nm templates with the potential to tune the electronic band structure of graphene via quantum confinement effects. Toward these ends, we report here the formation of well-defined one-dimensional organic nanostructures on epitaxial graphene via the self-assembly of 10,12-pentacosadiynoic acid (PCDA) in ultrahigh vacuum (UHV). Molecular resolution UHV scanning tunneling microscopy (STM) images confirm the one-dimensional ordering of the as-deposited PCDA monolayer and show domain boundaries with symmetry consistent with the underlying graphene lattice. In an effort to further stabilize the monolayer, in situ ultraviolet photopolymerization induces covalent bonding between neighboring PCDA molecules in a manner that maintains one-dimensional ordering as verified by UHV STM and ambient atomic force microscopy (AFM). Further quantitative insights into these experimental observations are provided by semiempirical quantum chemistry calculations that compare the molecular structure before and after photopolymerization.
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Affiliation(s)
- Aparna Deshpande
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
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33
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Zhan D, Yan J, Lai L, Ni Z, Liu L, Shen Z. Engineering the electronic structure of graphene. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:4055-4069. [PMID: 22760840 DOI: 10.1002/adma.201200011] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2012] [Revised: 05/07/2012] [Indexed: 06/01/2023]
Abstract
Graphene exhibits many unique electronic properties owing to its linear dispersive electronic band structure around the Dirac point, making it one of the most studied materials in the last 5-6 years. However, for many applications of graphene, further tuning its electronic band structure is necessary and has been extensively studied ever since graphene was first isolated experimentally. Here we review the major progresses made in electronic structure engineering of graphene, namely by electric and magnetic fields, chemical intercalation and adsorption, stacking geometry, edge-chirality, defects, as well as strain.
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Affiliation(s)
- Da Zhan
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
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34
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Yuan L, Li Z, Yang J, Hou JG. Diamondization of chemically functionalized graphene and graphene–BN bilayers. Phys Chem Chem Phys 2012; 14:8179-84. [DOI: 10.1039/c2cp40635g] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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35
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Yan L, Zheng YB, Zhao F, Li S, Gao X, Xu B, Weiss PS, Zhao Y. Chemistry and physics of a single atomic layer: strategies and challenges for functionalization of graphene and graphene-based materials. Chem Soc Rev 2011; 41:97-114. [PMID: 22086617 DOI: 10.1039/c1cs15193b] [Citation(s) in RCA: 274] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Graphene has attracted great interest for its superior physical, chemical, mechanical, and electrical properties that enable a wide range of applications from electronics to nanoelectromechanical systems. Functionalization is among the significant vectors that drive graphene towards technological applications. While the physical properties of graphene have been at the center of attention, we still lack the knowledge framework for targeted graphene functionalization. In this critical review, we describe some of the important chemical and physical processes for graphene functionalization. We also identify six major challenges in graphene research and give perspectives and practical strategies for both fundamental studies and applications of graphene (315 references).
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Affiliation(s)
- Liang Yan
- Chinese Academy of Sciences Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology of China, Beijing 100190, China
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36
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Haberer D, Giusca CE, Wang Y, Sachdev H, Fedorov AV, Farjam M, Jafari SA, Vyalikh DV, Usachov D, Liu X, Treske U, Grobosch M, Vilkov O, Adamchuk VK, Irle S, Silva SRP, Knupfer M, Büchner B, Grüneis A. Evidence for a new two-dimensional C4H-type polymer based on hydrogenated graphene. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2011; 23:4497-503. [PMID: 21997302 DOI: 10.1002/adma.201102019] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 07/15/2011] [Indexed: 05/20/2023]
Affiliation(s)
- Danny Haberer
- IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany.
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37
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Huang LF, Ni MY, Zhang GR, Zhou WH, Li YG, Zheng XH, Zeng Z. Modulation of the thermodynamic, kinetic, and magnetic properties of the hydrogen monomer on graphene by charge doping. J Chem Phys 2011; 135:064705. [DOI: 10.1063/1.3624657] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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38
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Chuang FC, Lin WH, Huang ZQ, Hsu CH, Kuo CC, Ozolins V, Yeh V. Electronic structures of an epitaxial graphene monolayer on SiC(0001) after gold intercalation: a first-principles study. NANOTECHNOLOGY 2011; 22:275704. [PMID: 21597151 DOI: 10.1088/0957-4484/22/27/275704] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The atomic and electronic structures of an Au-intercalated graphene monolayer on the SiC(0001) surface were investigated using first-principles calculations. The unique Dirac cone of graphene near the K point reappeared as the monolayer was intercalated by Au atoms. Coherent interfaces were used to study the mismatch and the strain at the boundaries. Our calculations showed that the strain at the graphene/Au and Au/SiC(0001) interfaces also played a key role in the electronic structures. Furthermore, we found that at an Au coverage of 3/8 ML, Au intercalation leads to a strong n-type doping of graphene. At 9/8 ML, it exhibited a weak p-type doping, indicative that graphene was not fully decoupled from the substrate. The shift in the Dirac point resulting from the electronic doping was not only due to the different electronegativities but also due to the strain at the interfaces. Our calculated positions of the Dirac points are consistent with those observed in the ARPES experiment (Gierz et al 2010 Phys. Rev. B 81 235408).
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Affiliation(s)
- Feng-Chuan Chuang
- Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
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39
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Lu Y, Feng YP. Adsorptions of hydrogen on graphene and other forms of carbon structures: First principle calculations. NANOSCALE 2011; 3:2444-2453. [PMID: 21512688 DOI: 10.1039/c1nr10118h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Carbon can exist in various structural forms (graphite, graphene, graphene-nanoribbon and flake) and these are technologically very important materials. On the other hand, hydrogen incorporation in these materials can significantly affect their structural and electronic properties. As it is difficult to observe hydrogenation processes directly in experiment and to measure the electronic states at atomic scale, first-principle calculations are widely used to investigate the interaction between hydrogen and various carbon-based structures in past years. In this article, we briefly review work done in recent years, theoretical understanding on the interaction between hydrogen and different forms of carbon materials and present a number of strategies to modify the properties of carbon-based systems.
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Affiliation(s)
- Yunhao Lu
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
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40
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The stretching vibration of hydrogen adsorbed on epitaxial graphene studied by sum-frequency generation spectroscopy. Chem Phys Lett 2011. [DOI: 10.1016/j.cplett.2011.04.025] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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41
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Abstract
A new model for graphene epitaxially grown on silicon carbide is proposed. Density functional theory modeling of epitaxial graphene functionalization by hydrogen, fluorine, methyl and phenyl groups has been performed, with hydrogen and fluorine showing a high probability of cluster formation in high adatom concentration. It has also been shown that the clusterization of fluorine adatoms provides midgap states in formation, due to significant flat distortion of graphene. The functionalization of epitaxial graphene using larger species (methyl and phenyl groups) renders cluster formation impossible, due to the steric effect, and results in uniform coverage with the energy gap opening.
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Affiliation(s)
- D W Boukhvalov
- Computational Materials Science Center, National Institute for Materials Science, Tsukuba, Ibaraki, Japan.
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42
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Hossain MZ, Walsh MA, Hersam MC. Scanning Tunneling Microscopy, Spectroscopy, and Nanolithography of Epitaxial Graphene Chemically Modified with Aryl Moieties. J Am Chem Soc 2010; 132:15399-403. [DOI: 10.1021/ja107085n] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Md. Zakir Hossain
- Department of Materials Science and Engineering and Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Michael A. Walsh
- Department of Materials Science and Engineering and Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Mark C. Hersam
- Department of Materials Science and Engineering and Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
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43
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Samarakoon DK, Wang XQ. Tunable band gap in hydrogenated bilayer graphene. ACS NANO 2010; 4:4126-4130. [PMID: 20536219 DOI: 10.1021/nn1007868] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We have studied the electronic structural characteristics of hydrogenated bilayer graphene under a perpendicular electric bias using first-principles density functional calculations. The bias voltage applied between the two hydrogenated graphene layers allows continuous tuning of the band gap and leads to transition from semiconducting to metallic state. Desorption of hydrogen from one layer in the chair conformation yields a ferromagnetic semiconductor with a tunable band gap. The implications of tailoring the band structure of biased system for future graphene-based device applications are discussed.
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Affiliation(s)
- Duminda K Samarakoon
- Department of Physics and Center for Functional Nanoscale Materials, Clark Atlanta University, Atlanta, Georgia 30314, USA
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44
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Jayasekera T, Kong BD, Kim KW, Buongiorno Nardelli M. Band engineering and magnetic doping of epitaxial graphene on SiC (0001). PHYSICAL REVIEW LETTERS 2010; 104:146801. [PMID: 20481952 DOI: 10.1103/physrevlett.104.146801] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2009] [Indexed: 05/29/2023]
Abstract
Using calculations from first principles we show how specific interface modifications can lead to a fine-tuning of the doping and band alignment in epitaxial graphene on SiC. Upon different choices of dopants, we demonstrate that one can achieve a variation of the valence band offset between the graphene Dirac point and the valence band edge of SiC up to 1.5 eV. Finally, via appropriate magnetic doping one can induce a half-metallic behavior in the first graphene monolayer. These results clearly establish the potential for graphene utilization in innovative electronic and spintronic devices.
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Affiliation(s)
- Thushari Jayasekera
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-7518, USA
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45
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Balog R, Jørgensen B, Nilsson L, Andersen M, Rienks E, Bianchi M, Fanetti M, Laegsgaard E, Baraldi A, Lizzit S, Sljivancanin Z, Besenbacher F, Hammer B, Pedersen TG, Hofmann P, Hornekaer L. Bandgap opening in graphene induced by patterned hydrogen adsorption. NATURE MATERIALS 2010; 9:315-319. [PMID: 20228819 DOI: 10.1038/nmat2710] [Citation(s) in RCA: 529] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Accepted: 01/27/2010] [Indexed: 05/28/2023]
Abstract
Graphene, a single layer of graphite, has recently attracted considerable attention owing to its remarkable electronic and structural properties and its possible applications in many emerging areas such as graphene-based electronic devices. The charge carriers in graphene behave like massless Dirac fermions, and graphene shows ballistic charge transport, turning it into an ideal material for circuit fabrication. However, graphene lacks a bandgap around the Fermi level, which is the defining concept for semiconductor materials and essential for controlling the conductivity by electronic means. Theory predicts that a tunable bandgap may be engineered by periodic modulations of the graphene lattice, but experimental evidence for this is so far lacking. Here, we demonstrate the existence of a bandgap opening in graphene, induced by the patterned adsorption of atomic hydrogen onto the Moiré superlattice positions of graphene grown on an Ir(111) substrate.
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46
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Abstract
In this report we review how intrinsic drawbacks of epitaxial graphene on SiC(0001)
such as n-doping and strong electronic influence of the substrate can be overcome. Besides
surface transfer doping from a strong electron acceptor and transfer of epitaxial graphene from
SiC(0001) to SiO2 the most promising route is to generate quasi-free standing epitaxial graphene
by means of hydrogen intercalation. The hydrogen moves between the (6p3×6p3)R30◦ reconstructed
initial carbon (so-called buffer) layer and the SiC substrate. The topmost Si atoms
which for epitaxial graphene are covalently bound to this buffer layer, are now saturated by
hydrogen bonds. The buffer layer is turned into a quasi-free standing graphene monolayer, epitaxial
monolayer graphene turns into a decoupled bilayer. The intercalation is stable in air and
can be reversed by annealing to around 900 °C. This technique offers significant advances in
epitaxial graphene based nanoelectronics.
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47
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Gao JH, Fujita D, Xu MS, Onishi K, Miyamoto S. Unique synthesis of few-layer graphene films on carbon-doped Pt(83)Rh(17) surfaces. ACS NANO 2010; 4:1026-1032. [PMID: 20104857 DOI: 10.1021/nn901255u] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We report a unique synthesis of single- and few-layer graphene films on carbon-doped Pt(83)Rh(17) surfaces by surface segregation and precipitation. The ultrathin graphene films were characterized by atomic force microscopy, Auger electron spectroscopy, and micro-Raman spectroscopy measurements, providing evidence of graphene film thickness and structural quality. The G and 2D band intensity images from micro-Raman spectroscopy measurements confirm that the graphene films with different coverage have very limited defects. Additionally, the 2D band peak can be well-fitted by a single Lozentian peak, indicating that graphene films are characteristic of single layer graphene. Graphene film thickness can be determined by analysis of Auger spectra, indicating that graphene films after 850 degrees C annealing mainly consist of monolayer graphene. By precise adjustment of annealing temperature, graphene film thickness and area size can be controlled and uniform large-area single-layer and double-layer graphene can be achieved.
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Affiliation(s)
- Jian-Hua Gao
- Advanced Nano Characterization Center, National Institute forMaterials Science, Ibaraki 305-0047, Japan.
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48
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Poon SW, Chen W, Wee ATS, Tok ES. Growth dynamics and kinetics of monolayer and multilayer graphene on a 6H-SiC(0001) substrate. Phys Chem Chem Phys 2010; 12:13522-33. [DOI: 10.1039/b927452a] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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49
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Samarakoon DK, Wang XQ. Chair and twist-boat membranes in hydrogenated graphene. ACS NANO 2009; 3:4017-4022. [PMID: 19947580 DOI: 10.1021/nn901317d] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Graphane is a two-dimensional system consisting of a single planar layer of fully saturated carbon atoms, which has recently been realized experimentally through hydrogenation of graphene membranes. We have studied the stability of chair, boat, and twist-boat graphane structures using first-principles density functional calculations. Our results indicate that locally stable twist-boat membranes significantly contribute to the experimentally observed lattice contraction. The band gaps of graphane nanoribbons decrease monotonically with the increase of the ribbon width and are insensitive to the edge structure. The implications of these results for future hydrogenated graphene applications are discussed.
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Riedl C, Coletti C, Iwasaki T, Zakharov AA, Starke U. Quasi-free-standing epitaxial graphene on SiC obtained by hydrogen intercalation. PHYSICAL REVIEW LETTERS 2009; 103:246804. [PMID: 20366220 DOI: 10.1103/physrevlett.103.246804] [Citation(s) in RCA: 296] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Indexed: 05/11/2023]
Abstract
Quasi-free-standing epitaxial graphene is obtained on SiC(0001) by hydrogen intercalation. The hydrogen moves between the (6 square root(3) x 6 square root(3))R30 degrees reconstructed initial carbon layer and the SiC substrate. The topmost Si atoms which for epitaxial graphene are covalently bound to this buffer layer, are now saturated by hydrogen bonds. The buffer layer is turned into a quasi-free-standing graphene monolayer with its typical linear pi bands. Similarly, epitaxial monolayer graphene turns into a decoupled bilayer. The intercalation is stable in air and can be reversed by annealing to around 900 degrees C.
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Affiliation(s)
- C Riedl
- Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany
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