301
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Grüneis A. Synthesis and electronic properties of chemically functionalized graphene on metal surfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:043001. [PMID: 23257769 DOI: 10.1088/0953-8984/25/4/043001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A review on the electronic properties, growth and functionalization of graphene on metals is presented. Starting from the derivation of the electronic properties of an isolated graphene layer using the nearest neighbor tight-binding (TB) approximation for π and σ electrons, the TB model is then extended to third-nearest neighbors and interlayer coupling. The latter is relevant to few-layer graphene and graphite. Next, the conditions under which epitaxial graphene can be obtained by chemical vapor deposition are reviewed with a particular emphasis on the Ni(111) surface. Regarding functionalization, I first discuss the intercalation of monolayer Au into the graphene/Ni(111) interface, which renders graphene quasi-free-standing. The Au intercalated quasi-free-standing graphene is then the basis for chemical functionalization. Functionalization of graphene is classified into covalent, ionic and substitutional functionalization. As archetypical examples for these three possibilities I discuss covalent functionalization by hydrogen, ionic functionalization by alkali metals and substitutional functionalization by nitrogen heteroatoms.
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Affiliation(s)
- Alexander Grüneis
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Wien, Austria.
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302
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Koepke JC, Wood JD, Estrada D, Ong ZY, He KT, Pop E, Lyding JW. Atomic-scale evidence for potential barriers and strong carrier scattering at graphene grain boundaries: a scanning tunneling microscopy study. ACS NANO 2013; 7:75-86. [PMID: 23237026 DOI: 10.1021/nn302064p] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We use scanning tunneling microscopy and spectroscopy to examine the electronic nature of grain boundaries (GBs) in polycrystalline graphene grown by chemical vapor deposition (CVD) on Cu foil and transferred to SiO(2) substrates. We find no preferential orientation angle between grains, and the GBs are continuous across graphene wrinkles and SiO(2) topography. Scanning tunneling spectroscopy shows enhanced empty states tunneling conductance for most of the GBs and a shift toward more n-type behavior compared to the bulk of the graphene. We also observe standing wave patterns adjacent to GBs propagating in a zigzag direction with a decay length of ~1 nm. Fourier analysis of these patterns indicates that backscattering and intervalley scattering are the dominant mechanisms responsible for the mobility reduction in the presence of GBs in CVD-grown graphene.
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Affiliation(s)
- Justin C Koepke
- Department of Electrical & Computer Engineering, University of Illinois, Urbana-Champaign, Illinois 61801, USA.
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303
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Wei D, Wu B, Guo Y, Yu G, Liu Y. Controllable chemical vapor deposition growth of few layer graphene for electronic devices. Acc Chem Res 2013; 46:106-15. [PMID: 22809220 DOI: 10.1021/ar300103f] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Because of its atomic thickness, excellent properties, and widespread applications, graphene is regarded as one of the most promising candidate materials for nanoelectronics. The wider use of graphene will require processes that produce this material in a controllable manner. In this Account, we focus on our recent studies of the controllable chemical vapor deposition (CVD) growth of graphene, especially few-layer graphene (FLG), and the applications of this material in electronic devices. CVD provides various means of control over the morphologies of the produced graph ene. We studied several variables that can affect the CVD growth of graphene, including the catalyst, gas flow rate, growth time, and growth temperature and successfully achieved the controlled growth of hexagonal graphene crystals. Moreover, we developed several modified CVD methods for the controlled growth of FLGs. Patterned CVD produced FLGs with desired shapes in required areas. By introducing dopant precursor in the CVD process, we produced substitutionally doped FLGs, avoiding the typically complicated post-treatment processes for graphene doping. We developed a template CVD method to produce FLG ribbons with controllable morphologies on a large scale. An oxidation-activated surface facilitated the CVD growth of polycrystalline graphene without the use of a metal catalyst or a complicated postgrowth transfer process. In devices, CVD offers a controllable means to modulate the electronic properties of the graphene samples and to improve device performance. Using CVD-grown hexagonal graphene crystals as the channel materials in field-effect transistors (FETs), we improved carrier mobility. Substitutional doping of graphene in CVD opened a band gap for efficient FET operation and modulated the Fermi energy level for n-type or p-type features. The similarity between the chemical structure of graphene and organic semiconductors suggests potential applications of graphene in organic devices. We used patterned CVD FLGs as the bottom electrodes in pentacene FETs. The strong π-π interactions between graphene and pentacene produced an excellent interface with low contact resistance and a reduced injection barrier, which dramatically enhances the device performance. We also fabricated reversible nanoelectromechanical (NEM) switches and a logic gate using the FLG ribbons produced using our template CVD method. In summary, CVD provides a controllable means to produce graphene samples with both large area and high quality. We developed several modified CVD methods to produce FLG samples with controlled shape, location, edge, layer, dopant, and growth substrate. As a result, we can modulate the properties of FLGs, which provides materials that could be used in FETs, OFETs, and NEM devices. Despite remarkable advances in this field, further exploration is required to produce consistent, homogeneous graphene samples with single layer, single crystal, and large area for graphene-based electronics.
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Affiliation(s)
- Dacheng Wei
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Physics Department, National University of Singapore, 2 Science Drive 3, Singapore 117542
| | - Bin Wu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Yunlong Guo
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Gui Yu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Yunqi Liu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
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304
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Gao Y, Hu G, Zhong J, Shi Z, Zhu Y, Su DS, Wang J, Bao X, Ma D. Stickstoffdotierter sp2
-hybridisierter Kohlenstoff als hervorragender Oxidationskatalysator. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201207918] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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305
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Gao Y, Hu G, Zhong J, Shi Z, Zhu Y, Su DS, Wang J, Bao X, Ma D. Nitrogen-Doped sp2-Hybridized Carbon as a Superior Catalyst for Selective Oxidation. Angew Chem Int Ed Engl 2013; 52:2109-13. [DOI: 10.1002/anie.201207918] [Citation(s) in RCA: 411] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Indexed: 11/08/2022]
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306
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307
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Xue Y, Yu D, Dai L, Wang R, Li D, Roy A, Lu F, Chen H, Liu Y, Qu J. Three-dimensional B,N-doped graphene foam as a metal-free catalyst for oxygen reduction reaction. Phys Chem Chem Phys 2013; 15:12220-6. [DOI: 10.1039/c3cp51942b] [Citation(s) in RCA: 262] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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308
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Wang XQ, Li HD, Wang JT. Prediction of a new two-dimensional metallic carbon allotrope. Phys Chem Chem Phys 2013; 15:2024-30. [DOI: 10.1039/c2cp43070c] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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309
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Velez-Fort E, Mathieu C, Pallecchi E, Pigneur M, Silly MG, Belkhou R, Marangolo M, Shukla A, Sirotti F, Ouerghi A. Epitaxial graphene on 4H-SiC(0001) grown under nitrogen flux: evidence of low nitrogen doping and high charge transfer. ACS NANO 2012; 6:10893-10900. [PMID: 23148722 DOI: 10.1021/nn304315z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Nitrogen doping of graphene is of great interest for both fundamental research to explore the effect of dopants on a 2D electrical conductor and applications such as lithium storage, composites, and nanoelectronic devices. Here, we report on the modifications of the electronic properties of epitaxial graphene thanks to the introduction, during the growth, of nitrogen-atom substitution in the carbon honeycomb lattice. High-resolution transmission microscopy and low-energy electron microscopy investigations indicate that the nitrogen-doped graphene is uniform at large scale. The substitution of nitrogen atoms in the graphene planes was confirmed by high-resolution X-ray photoelectron spectroscopy, which reveals several atomic configurations for the nitrogen atoms: graphitic-like, pyridine-like, and pyrrolic-like. Angle-resolved photoemission measurements show that the N-doped graphene exhibits large n-type carrier concentrations of 2.6 × 10(13) cm(-2), about 4 times more than what is found for pristine graphene, grown under similar pressure conditions. Our experiments demonstrate that a small amount of dopants (<1%) can significantly tune the electronic properties of graphene by shifting the Dirac cone about 0.3 eV toward higher binding energies with respect to the π band of pristine graphene, which is a key feature for envisioning applications in nanoelectronics.
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Affiliation(s)
- Emilio Velez-Fort
- Laboratoire de Photonique et de Nanostructures (CNRS-LPN), Route de Nozay, 91460 Marcoussis, France
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310
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Boneschanscher MP, van der Lit J, Sun Z, Swart I, Liljeroth P, Vanmaekelbergh D. Quantitative atomic resolution force imaging on epitaxial graphene with reactive and nonreactive AFM probes. ACS NANO 2012; 6:10216-21. [PMID: 23039032 DOI: 10.1021/nn3040155] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Atomic force microscopy (AFM) images of graphene and graphite show contrast with atomic periodicity. However, the contrast patterns vary depending on the atomic termination of the AFM tip apex and the tip-sample distance, hampering the identification of the atomic positions. Here, we report quantitative AFM imaging of epitaxial graphene using inert (carbon-monoxide-terminated) and reactive (iridium-terminated) tips. The atomic image contrast is markedly different with these tip terminations. With a reactive tip, we observe an inversion from attractive to repulsive atomic contrast with decreasing tip-sample distance, while a nonreactive tip only yields repulsive atomic contrast. We are able to identify the atoms with both tips at any tip-sample distance. This is a prerequisite for future structural and chemical analysis of adatoms, defects, and the edges of graphene nanostructures, crucial for understanding nanoscale graphene devices.
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Affiliation(s)
- Mark P Boneschanscher
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
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311
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Zhou W, Kapetanakis MD, Prange MP, Pantelides ST, Pennycook SJ, Idrobo JC. Direct determination of the chemical bonding of individual impurities in graphene. PHYSICAL REVIEW LETTERS 2012; 109:206803. [PMID: 23215517 DOI: 10.1103/physrevlett.109.206803] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Indexed: 05/08/2023]
Abstract
Using a combination of Z-contrast imaging and atomically resolved electron energy-loss spectroscopy on a scanning transmission electron microscope, we show that the chemical bonding of individual impurity atoms can be deduced experimentally. We find that when a Si atom is bonded with four atoms at a double-vacancy site in graphene, Si 3d orbitals contribute significantly to the bonding, resulting in a planar sp(2) d-like hybridization, whereas threefold coordinated Si in graphene adopts the preferred sp(3) hybridization. The conclusions are confirmed by first-principles calculations and demonstrate that chemical bonding of two-dimensional materials can now be explored at the single impurity level.
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Affiliation(s)
- Wu Zhou
- Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA.
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312
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Weiss NO, Zhou H, Liao L, Liu Y, Jiang S, Huang Y, Duan X. Graphene: an emerging electronic material. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:5782-825. [PMID: 22930422 DOI: 10.1002/adma.201201482] [Citation(s) in RCA: 168] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 06/14/2012] [Indexed: 05/06/2023]
Abstract
Graphene, a single layer of carbon atoms in a honeycomb lattice, offers a number of fundamentally superior qualities that make it a promising material for a wide range of applications, particularly in electronic devices. Its unique form factor and exceptional physical properties have the potential to enable an entirely new generation of technologies beyond the limits of conventional materials. The extraordinarily high carrier mobility and saturation velocity can enable a fast switching speed for radio-frequency analog circuits. Unadulterated graphene is a semi-metal, incapable of a true off-state, which typically precludes its applications in digital logic electronics without bandgap engineering. The versatility of graphene-based devices goes beyond conventional transistor circuits and includes flexible and transparent electronics, optoelectronics, sensors, electromechanical systems, and energy technologies. Many challenges remain before this relatively new material becomes commercially viable, but laboratory prototypes have already shown the numerous advantages and novel functionality that graphene provides.
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Affiliation(s)
- Nathan O Weiss
- Department of Materials Science and Engineering, UCLA, Los Angeles, CA 90095, USA
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313
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Li Q, Zhang S, Dai L, Li LS. Nitrogen-doped colloidal graphene quantum dots and their size-dependent electrocatalytic activity for the oxygen reduction reaction. J Am Chem Soc 2012; 134:18932-5. [PMID: 23126520 DOI: 10.1021/ja309270h] [Citation(s) in RCA: 298] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Nitrogen doping has been a powerful way to modify the properties of carbon materials ranging from activated carbon to graphene. Here we report on a solution chemistry approach to nitrogen-doped colloidal graphene quantum dots with well-defined structures. N-doping was demonstrated to significantly affect the properties of the quantum dots, including the emergence of size-dependent electrocatalytic activity for the oxygen reduction reaction.
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Affiliation(s)
- Qiqi Li
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA
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314
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Susi T, Kotakoski J, Arenal R, Kurasch S, Jiang H, Skakalova V, Stephan O, Krasheninnikov AV, Kauppinen EI, Kaiser U, Meyer JC. Atomistic description of electron beam damage in nitrogen-doped graphene and single-walled carbon nanotubes. ACS NANO 2012; 6:8837-46. [PMID: 23009666 DOI: 10.1021/nn303944f] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
By combining ab initio simulations with state-of-the-art electron microscopy and electron energy loss spectroscopy, we study the mechanism of electron beam damage in nitrogen-doped graphene and carbon nanotubes. Our results show that the incorporation of nitrogen atoms results in noticeable knock-on damage in these structures already at an acceleration voltage of 80 kV, at which essentially no damage is created in pristine structures at corresponding doses. Contrary to an early estimate predicting rapid destruction via sputtering of the nitrogen atoms, in the case of substitutional doping, damage is initiated by displacement of carbon atoms neighboring the nitrogen dopant, leading to the conversion of substitutional dopant sites into pyridinic ones. Although such events are relatively rare at 80 kV, they become significant at higher voltages typically used in electron energy loss spectroscopy studies. Correspondingly, we measured an energy loss spectrum time series at 100 kV that provides direct evidence for such conversions in nitrogen-doped single-walled carbon nanotubes, in excellent agreement with our theoretical prediction. Besides providing an improved understanding of the irradiation stability of these structures, we show that structural changes cannot be neglected in their characterization employing high-energy electrons.
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Affiliation(s)
- Toma Susi
- Nanomaterials Group, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, 00076 Aalto, Finland.
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315
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Georgakilas V, Otyepka M, Bourlinos AB, Chandra V, Kim N, Kemp KC, Hobza P, Zboril R, Kim KS. Functionalization of graphene: covalent and non-covalent approaches, derivatives and applications. Chem Rev 2012; 112:6156-214. [PMID: 23009634 DOI: 10.1021/cr3000412] [Citation(s) in RCA: 1829] [Impact Index Per Article: 152.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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316
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Marconcini P, Cresti A, Triozon F, Fiori G, Biel B, Niquet YM, Macucci M, Roche S. Atomistic boron-doped graphene field-effect transistors: a route toward unipolar characteristics. ACS NANO 2012; 6:7942-7947. [PMID: 22876866 DOI: 10.1021/nn3024046] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report fully quantum simulations of realistic models of boron-doped graphene-based field-effect transistors, including atomistic details based on DFT calculations. We show that the self-consistent solution of the three-dimensional (3D) Poisson and Schrödinger equations with a representation in terms of a tight-binding Hamiltonian manages to accurately reproduce the DFT results for an isolated boron-doped graphene nanoribbon. Using a 3D Poisson/Schrödinger solver within the non-equilibrium Green's function (NEGF) formalism, self-consistent calculations of the gate-screened scattering potentials induced by the boron impurities have been performed, allowing the theoretical exploration of the tunability of transistor characteristics. The boron-doped graphene transistors are found to approach unipolar behavior as the boron concentration is increased and, by tuning the density of chemical dopants, the electron-hole transport asymmetry can be finely adjusted. Correspondingly, the onset of a mobility gap in the device is observed. Although the computed asymmetries are not sufficient to warrant proper device operation, our results represent an initial step in the direction of improved transfer characteristics and, in particular, the developed simulation strategy is a powerful new tool for modeling doped graphene nanostructures.
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Affiliation(s)
- Paolo Marconcini
- Dipartimento di Ingegneria dell'Informazione, Università di Pisa, Via Caruso 16, 56122 Pisa, Italy
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317
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Sutter P, Cortes R, Lahiri J, Sutter E. Interface formation in monolayer graphene-boron nitride heterostructures. NANO LETTERS 2012; 12:4869-4874. [PMID: 22871166 DOI: 10.1021/nl302398m] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The ability to control the formation of interfaces between different materials has become one of the foundations of modern materials science. With the advent of two-dimensional (2D) crystals, low-dimensional equivalents of conventional interfaces can be envisioned: line boundaries separating different materials integrated in a single 2D sheet. Graphene and hexagonal boron nitride offer an attractive system from which to build such 2D heterostructures. They are isostructural, nearly lattice-matched, and isoelectronic, yet their different band structures promise interesting functional properties arising from their integration. Here, we use a combination of in situ microscopy techniques to study the growth and interface formation of monolayer graphene-boron nitride heterostructures on ruthenium. In a sequential chemical vapor deposition process, boron nitride grows preferentially at the edges of existing monolayer graphene domains, which can be exploited for synthesizing continuous 2D membranes of graphene embedded in boron nitride. High-temperature growth leads to intermixing near the interface, similar to interfacial alloying in conventional heterostructures. Using real-time microscopy, we identify processes that eliminate this intermixing and thus pave the way to graphene-boron nitride heterostructures with atomically sharp interfaces.
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Affiliation(s)
- P Sutter
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States.
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318
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Graphene and boron nitride lateral heterostructures for atomically thin circuitry. Nature 2012; 488:627-32. [DOI: 10.1038/nature11408] [Citation(s) in RCA: 681] [Impact Index Per Article: 56.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 07/10/2012] [Indexed: 12/22/2022]
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319
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Nitrogen-doped graphene: beyond single substitution and enhanced molecular sensing. Sci Rep 2012. [PMID: 22905317 DOI: 10.1038/srep00586.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Graphene is a two-dimensional network in which sp(2)-hybridized carbon atoms are arranged in two different triangular sub-lattices (A and B). By incorporating nitrogen atoms into graphene, its physico-chemical properties could be significantly altered depending on the doping configuration within the sub-lattices. Here, we describe the synthesis of large-area, highly-crystalline monolayer N-doped graphene (NG) sheets via atmospheric-pressure chemical vapor deposition, yielding a unique N-doping site composed of two quasi-adjacent substitutional nitrogen atoms within the same graphene sub-lattice (N(2)(AA)). Scanning tunneling microscopy and spectroscopy (STM and STS) of NG revealed the presence of localized states in the conduction band induced by N(2)(AA)-doping, which was confirmed by ab initio calculations. Furthermore, we demonstrated for the first time that NG could be used to efficiently probe organic molecules via a highly improved graphene enhanced Raman scattering.
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320
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Li XH, Kurasch S, Kaiser U, Antonietti M. Synthese von “Patchwork”-Graphen aus Glucose. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201203207] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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321
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Li XH, Kurasch S, Kaiser U, Antonietti M. Synthesis of Monolayer-Patched Graphene from Glucose. Angew Chem Int Ed Engl 2012; 51:9689-92. [DOI: 10.1002/anie.201203207] [Citation(s) in RCA: 347] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Indexed: 11/11/2022]
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322
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Nitrogen-doped graphene: beyond single substitution and enhanced molecular sensing. Sci Rep 2012; 2:586. [PMID: 22905317 PMCID: PMC3421434 DOI: 10.1038/srep00586] [Citation(s) in RCA: 520] [Impact Index Per Article: 43.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 07/30/2012] [Indexed: 12/03/2022] Open
Abstract
Graphene is a two-dimensional network in which sp2-hybridized carbon atoms are arranged in two different triangular sub-lattices (A and B). By incorporating nitrogen atoms into graphene, its physico-chemical properties could be significantly altered depending on the doping configuration within the sub-lattices. Here, we describe the synthesis of large-area, highly-crystalline monolayer N-doped graphene (NG) sheets via atmospheric-pressure chemical vapor deposition, yielding a unique N-doping site composed of two quasi-adjacent substitutional nitrogen atoms within the same graphene sub-lattice (N2AA). Scanning tunneling microscopy and spectroscopy (STM and STS) of NG revealed the presence of localized states in the conduction band induced by N2AA-doping, which was confirmed by ab initio calculations. Furthermore, we demonstrated for the first time that NG could be used to efficiently probe organic molecules via a highly improved graphene enhanced Raman scattering.
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323
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Schiros T, Nordlund D, Pálová L, Prezzi D, Zhao L, Kim KS, Wurstbauer U, Gutiérrez C, Delongchamp D, Jaye C, Fischer D, Ogasawara H, Pettersson LGM, Reichman DR, Kim P, Hybertsen MS, Pasupathy AN. Connecting dopant bond type with electronic structure in N-doped graphene. NANO LETTERS 2012; 12:4025-31. [PMID: 22746249 DOI: 10.1021/nl301409h] [Citation(s) in RCA: 207] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Robust methods to tune the unique electronic properties of graphene by chemical modification are in great demand due to the potential of the two dimensional material to impact a range of device applications. Here we show that carbon and nitrogen core-level resonant X-ray spectroscopy is a sensitive probe of chemical bonding and electronic structure of chemical dopants introduced in single-sheet graphene films. In conjunction with density functional theory based calculations, we are able to obtain a detailed picture of bond types and electronic structure in graphene doped with nitrogen at the sub-percent level. We show that different N-bond types, including graphitic, pyridinic, and nitrilic, can exist in a single, dilutely N-doped graphene sheet. We show that these various bond types have profoundly different effects on the carrier concentration, indicating that control over the dopant bond type is a crucial requirement in advancing graphene electronics.
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Affiliation(s)
- Theanne Schiros
- Energy Frontier Research Center, Columbia University, New York, New York 10027, USA.
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324
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Philpott MR, Kawazoe Y. Magnetism and structure of graphene nanodots with interiors modified by boron, nitrogen, and charge. J Chem Phys 2012; 137:054715. [DOI: 10.1063/1.4742193] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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325
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Chen L, Liu CC, Feng B, He X, Cheng P, Ding Z, Meng S, Yao Y, Wu K. Evidence for Dirac fermions in a honeycomb lattice based on silicon. PHYSICAL REVIEW LETTERS 2012; 109:056804. [PMID: 23006197 DOI: 10.1103/physrevlett.109.056804] [Citation(s) in RCA: 203] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Indexed: 06/01/2023]
Abstract
Silicene, a sheet of silicon atoms in a honeycomb lattice, was proposed to be a new Dirac-type electron system similar to graphene. We performed scanning tunneling microscopy and spectroscopy studies on the atomic and electronic properties of silicene on Ag(111). An unexpected √3 × √3 reconstruction was found, which is explained by an extra-buckling model. Pronounced quasiparticle interferences (QPI) patterns, originating from both the intervalley and intravalley scatter, were observed. From the QPI patterns we derived a linear energy-momentum dispersion and a large Fermi velocity, which prove the existence of Dirac fermions in silicene.
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Affiliation(s)
- Lan Chen
- Institute of Physics, Chinese Academy of Sciences, Beijing, China
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326
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Kim YA, Fujisawa K, Muramatsu H, Hayashi T, Endo M, Fujimori T, Kaneko K, Terrones M, Behrends J, Eckmann A, Casiraghi C, Novoselov KS, Saito R, Dresselhaus MS. Raman spectroscopy of boron-doped single-layer graphene. ACS NANO 2012; 6:6293-300. [PMID: 22695033 DOI: 10.1021/nn301728j] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The introduction of foreign atoms, such as nitrogen, into the hexagonal network of an sp(2)-hybridized carbon atom monolayer has been demonstrated and constitutes an effective tool for tailoring the intrinsic properties of graphene. Here, we report that boron atoms can be efficiently substituted for carbon in graphene. Single-layer graphene substitutionally doped with boron was prepared by the mechanical exfoliation of boron-doped graphite. X-ray photoelectron spectroscopy demonstrated that the amount of substitutional boron in graphite was ~0.22 atom %. Raman spectroscopy demonstrated that the boron atoms were spaced 4.76 nm apart in single-layer graphene. The 7-fold higher intensity of the D-band when compared to the G-band was explained by the elastically scattered photoexcited electrons by boron atoms before emitting a phonon. The frequency of the G-band in single-layer substitutionally boron-doped graphene was unchanged, which could be explained by the p-type boron doping (stiffening) counteracting the tensile strain effect of the larger carbon-boron bond length (softening). Boron-doped graphene appears to be a useful tool for engineering the physical and chemical properties of graphene.
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Affiliation(s)
- Yoong Ahm Kim
- Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano, Japan.
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327
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Feng B, Ding Z, Meng S, Yao Y, He X, Cheng P, Chen L, Wu K. Evidence of silicene in honeycomb structures of silicon on Ag(111). NANO LETTERS 2012; 12:3507-11. [PMID: 22658061 DOI: 10.1021/nl301047g] [Citation(s) in RCA: 436] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
In the search for evidence of silicene, a two-dimensional honeycomb lattice of silicon, it is important to obtain a complete picture for the evolution of Si structures on Ag(111), which is believed to be the most suitable substrate for growth of silicene so far. In this work we report the finding and evolution of several monolayer superstructures of silicon on Ag(111), depending on the coverage and temperature. Combined with first-principles calculations, the detailed structures of these phases have been illuminated. These structures were found to share common building blocks of silicon rings, and they evolve from a fragment of silicene to a complete monolayer silicene and multilayer silicene. Our results elucidate how silicene forms on Ag(111) surface and provides methods to synthesize high-quality and large-scale silicene.
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Affiliation(s)
- Baojie Feng
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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328
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Abstract
Graphene is an allotrope of carbon whose structure is based on one-atom-thick planar sheets of carbon atoms that are densely packed in a honeycomb crystal lattice. Its unique electrical and optical properties raised worldwide interest towards the design and fabrication of future electronic and optical devices with unmatched performance. At the moment, extensive efforts are underway to evaluate the reliability and performance of a number of such devices. With the recent advances in synthesizing large-area graphene sheets, engineers have begun investigating viable methodologies for conducting graphene metrology and quality control at industrial scales to understand a variety of reliability issues including defects, patternability, electrical, and physical properties. This review summarizes the current state of industrial graphene metrology and provides an overview of graphene metrology techniques. In addition, a recently developed large-area graphene metrology technique based on fluorescence quenching is introduced. For each metrology technique, the industrial metrics it measures are identified--layer thickness, edge structure, defects, Fermi level, and thermal conductivity--and a detailed description is provided as to how the measurements are performed. Additionally, the potential advantages of each technique for industrial use are identified, including throughput, scalability, sensitivity to substrate/environment, and on their demonstrated ability to achieve quantified results. The recently developed fluorescence-quenching metrology technique is shown to meet all the necessary criteria for industrial applications, rendering it the first industry-ready graphene metrology technique.
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Affiliation(s)
- Jennifer Reiber Kyle
- Department of Electrical Engineering, University of California, Riverside, CA, USA
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329
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Kumar A, Ganguly A, Papakonstantinou P. Thermal stability study of nitrogen functionalities in a graphene network. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:235503. [PMID: 22576101 DOI: 10.1088/0953-8984/24/23/235503] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Catalyst-free vertically aligned graphene nanoflakes possessing a large amount of high density edge planes were functionalized using nitrogen species in a low energy N(+) ion bombardment process to achieve pyridinic, cyanide and nitrogen substitution in hexagonal graphitic coordinated units. The evolution of the electronic structure of the functionalized graphene nanoflakes over the temperature range 20-800 °C was investigated in situ, using high resolution x-ray photoemission spectroscopy. We demonstrate that low energy irradiation is a useful tool for achieving nitrogen doping levels up to 9.6 at.%. Pyridinic configurations are found to be predominant at room temperature, while at 800 °C graphitic nitrogen configurations become the dominant ones. The findings have helped to provide an understanding of the thermal stability of nitrogen functionalities in graphene, and offer prospects for controllable tuning of nitrogen doping in device applications.
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Affiliation(s)
- Ajay Kumar
- Engineering Research Institute (ERI), School of Engineering, University of Ulster, Newtownabbey, UK.
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330
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Zhang L, Niu J, Dai L, Xia Z. Effect of microstructure of nitrogen-doped graphene on oxygen reduction activity in fuel cells. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:7542-7550. [PMID: 22489601 DOI: 10.1021/la2043262] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The development of fuel cells as clean-energy technologies is largely limited by the prohibitive cost of the noble-metal catalysts needed for catalyzing the oxygen reduction reaction (ORR) in fuel cells. A fundamental understanding of catalyst design principle that links material structures to the catalytic activity can accelerate the search for highly active and abundant nonmetal catalysts to replace platinum. Here, we present a first-principles study of ORR on nitrogen-doped graphene in acidic environment. We demonstrate that the ORR activity primarily correlates to charge and spin densities of the graphene. The nitrogen doping and defects introduce high positive spin and/or charge densities that facilitate the ORR on graphene surface. The identified active sites are closely related to doping cluster size and dopant-defect interactions. Generally speaking, a large doping cluster size (number of N atoms >2) reduces the number of catalytic active sites per N atom. In combination with N clustering, Stone-Wales defects can strongly promote ORR. For four-electron transfer, the effective reversible potential ranges from 1.04 to 1.15 V/SHE, depending on the defects and cluster size. The catalytic properties of graphene could be optimized by introducing small N clusters in combination with material defects.
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Affiliation(s)
- Lipeng Zhang
- Department of Mechanical Engineering, University of Akron, Akron, Ohio 44325, USA
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331
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Yang J, Kim JW, Shin HS. Facile method for rGO field effect transistor: selective adsorption of rGO on SAM-treated gold electrode by electrostatic attraction. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:2299-2303. [PMID: 22473570 DOI: 10.1002/adma.201104094] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 12/30/2011] [Indexed: 05/31/2023]
Abstract
A facile method for the fabrication of negatively and positively charged rGO field effect transistors (FETs) is proposed, which utilizes electrostatic attraction between electrodes and rGO sheets. Negatively and positively charged rGO sheets are functionalized with carboxylic acid and amine groups, respectively. The FET of amine-functionalized rGO exhibits an n-doping effect. The FET devices fabricated by this method show high mobility of carriers.
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Affiliation(s)
- Jieun Yang
- Interdisciplinary School of Green Energy, Low Dimensional Carbon Materials Center and KIER-UNIST Advanced Center for Energy, Ulsan National Institute of Science & Technology (UNIST), UNIST-gil 50, Ulsan, Republic of Korea
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332
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Andrei EY, Li G, Du X. Electronic properties of graphene: a perspective from scanning tunneling microscopy and magnetotransport. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2012; 75:056501. [PMID: 22790587 DOI: 10.1088/0034-4885/75/5/056501] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
This review covers recent experimental progress in probing the electronic properties of graphene and how they are influenced by various substrates, by the presence of a magnetic field and by the proximity to a superconductor. The focus is on results obtained using scanning tunneling microscopy, spectroscopy, transport and magnetotransport techniques.
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Affiliation(s)
- Eva Y Andrei
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08855, USA
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333
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Wang H, Li K, Cheng Y, Wang Q, Yao Y, Schwingenschlögl U, Zhang X, Yang W. Interaction between single gold atom and the graphene edge: a study via aberration-corrected transmission electron microscopy. NANOSCALE 2012; 4:2920-2925. [PMID: 22456496 DOI: 10.1039/c2nr00059h] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Interaction between single noble metal atoms and graphene edges has been investigated via aberration-corrected and monochromated transmission electron microscopy. A collective motion of the Au atom and the nearby carbon atoms is observed in transition between energy-favorable configurations. Most trapping and detrapping processes are assisted by the dangling carbon atoms, which are more susceptible to knock-on displacements by electron irradiation. Thermal energy is lower than the activation barriers in transition among different energy-favorable configurations, which suggests electron-beam irradiation can be an efficient way of engineering the graphene edge with metal atoms.
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Affiliation(s)
- Hongtao Wang
- Institute of Applied Mechanics, Zhejiang University, Hangzhou 310027, China
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334
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Wang H, Maiyalagan T, Wang X. Review on Recent Progress in Nitrogen-Doped Graphene: Synthesis, Characterization, and Its Potential Applications. ACS Catal 2012. [DOI: 10.1021/cs200652y] [Citation(s) in RCA: 2806] [Impact Index Per Article: 233.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Haibo Wang
- School of
Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive,
Singapore, 637459
| | - Thandavarayan Maiyalagan
- School of
Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive,
Singapore, 637459
| | - Xin Wang
- School of
Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive,
Singapore, 637459
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335
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Long J, Xie X, Xu J, Gu Q, Chen L, Wang X. Nitrogen-Doped Graphene Nanosheets as Metal-Free Catalysts for Aerobic Selective Oxidation of Benzylic Alcohols. ACS Catal 2012. [DOI: 10.1021/cs3000396] [Citation(s) in RCA: 336] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jinlin Long
- Research Institute of Photocatalysis, Fujian Provincial Key Laboratory of Photocatalysis, State Key Laboratory Breeding Base, Fuzhou University, Fuzhou 350002, People’s Republic of China
| | - Xiuqiang Xie
- Research Institute of Photocatalysis, Fujian Provincial Key Laboratory of Photocatalysis, State Key Laboratory Breeding Base, Fuzhou University, Fuzhou 350002, People’s Republic of China
| | - Jie Xu
- Research Institute of Photocatalysis, Fujian Provincial Key Laboratory of Photocatalysis, State Key Laboratory Breeding Base, Fuzhou University, Fuzhou 350002, People’s Republic of China
| | - Quan Gu
- Research Institute of Photocatalysis, Fujian Provincial Key Laboratory of Photocatalysis, State Key Laboratory Breeding Base, Fuzhou University, Fuzhou 350002, People’s Republic of China
| | - Liming Chen
- Research Institute of Photocatalysis, Fujian Provincial Key Laboratory of Photocatalysis, State Key Laboratory Breeding Base, Fuzhou University, Fuzhou 350002, People’s Republic of China
| | - Xuxu Wang
- Research Institute of Photocatalysis, Fujian Provincial Key Laboratory of Photocatalysis, State Key Laboratory Breeding Base, Fuzhou University, Fuzhou 350002, People’s Republic of China
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336
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Cao P, Varghese JO, Xu K, Heath JR. Visualizing local doping effects of individual water clusters on gold(111)-supported graphene. NANO LETTERS 2012; 12:1459-1463. [PMID: 22324337 DOI: 10.1021/nl2041673] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The local charge carrier density of graphene can exhibit significant and highly localized variations that arise from the interaction between graphene and the local environment, such as adsorbed water, or a supporting substrate. However, it has been difficult to correlate such spatial variations with individual impurity sites. By trapping (under graphene) nanometer-sized water clusters on the atomically well-defined Au(111) substrate, we utilize scanning tunneling microscopy and spectroscopy to characterize the local doping influence of individual water clusters on graphene. We find that water clusters, predominantly nucleated at the atomic steps of Au(111), induce strong and highly localized electron doping in graphene. A positive correlation is observed between the water cluster size and the local doping level, in support of the recently proposed electrostatic-field-mediated doping mechanism. Our findings quantitatively demonstrate the importance of substrate-adsorbed water on the electronic properties of graphene.
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Affiliation(s)
- Peigen Cao
- Kavli Nanoscience Institute and Division of Chemistry and Chemical Engineering, California Institute of Technology, MC 127-72, Pasadena, California 91125, USA
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337
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Wang H, Wang Q, Cheng Y, Li K, Yao Y, Zhang Q, Dong C, Wang P, Schwingenschlögl U, Yang W, Zhang XX. Doping monolayer graphene with single atom substitutions. NANO LETTERS 2012; 12:141-144. [PMID: 22136503 DOI: 10.1021/nl2031629] [Citation(s) in RCA: 236] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Functionalized graphene has been extensively studied with the aim of tailoring properties for gas sensors, superconductors, supercapacitors, nanoelectronics, and spintronics. A bottleneck is the capability to control the carrier type and density by doping. We demonstrate that a two-step process is an efficient way to dope graphene: create vacancies by high-energy atom/ion bombardment and fill these vacancies with desired dopants. Different elements (Pt, Co, and In) have been successfully doped in the single-atom form. The high binding energy of the metal-vacancy complex ensures its stability and is consistent with in situ observation by an aberration-corrected and monochromated transmission electron microscope.
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Affiliation(s)
- Hongtao Wang
- Institute of Applied Mechanics, Zhejiang University, Hangzhou 310027, China
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338
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Wu P, Qian Y, Du P, Zhang H, Cai C. Facile synthesis of nitrogen-doped graphene for measuring the releasing process of hydrogen peroxide from living cells. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm16929k] [Citation(s) in RCA: 184] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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339
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Wu T, Shen H, Sun L, Cheng B, Liu B, Shen J. Nitrogen and boron doped monolayer graphene by chemical vapor deposition using polystyrene, urea and boric acid. NEW J CHEM 2012. [DOI: 10.1039/c2nj40068e] [Citation(s) in RCA: 166] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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340
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Wang XQ, Li HD, Wang JT. Structural stabilities and electronic properties of planar C4 carbon sheet and nanoribbons. Phys Chem Chem Phys 2012; 14:11107-11. [PMID: 22763793 DOI: 10.1039/c2cp41464c] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Xin-Quan Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
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341
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Usachov D, Vilkov O, Grüneis A, Haberer D, Fedorov A, Adamchuk VK, Preobrajenski AB, Dudin P, Barinov A, Oehzelt M, Laubschat C, Vyalikh DV. Nitrogen-doped graphene: efficient growth, structure, and electronic properties. NANO LETTERS 2011; 11:5401-7. [PMID: 22077830 DOI: 10.1021/nl2031037] [Citation(s) in RCA: 297] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
A novel strategy for efficient growth of nitrogen-doped graphene (N-graphene) on a large scale from s-triazine molecules is presented. The growth process has been unveiled in situ using time-dependent photoemission. It has been established that a postannealing of N-graphene after gold intercalation causes a conversion of the N environment from pyridinic to graphitic, allowing to obtain more than 80% of all embedded nitrogen in graphitic form, which is essential for the electron doping in graphene. A band gap, a doping level of 300 meV, and a charge-carrier concentration of ∼8×10(12) electrons per cm2, induced by 0.4 atom % of graphitic nitrogen, have been detected by angle-resolved photoemission spectroscopy, which offers great promise for implementation of this system in next generation electronic devices.
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Affiliation(s)
- D Usachov
- St. Petersburg State University, St. Petersburg, 198504, Russia.
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342
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Affiliation(s)
- George W. Flynn
- Department of Chemistry, Nanoscale Science and Engineering Center, and Energy Frontier Research Center, Columbia University, 3000 Broadway, MC 3109, New York, New York 10027, USA
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