201
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Robertson AW, Lee GD, He K, Yoon E, Kirkland AI, Warner JH. The role of the bridging atom in stabilizing odd numbered graphene vacancies. NANO LETTERS 2014; 14:3972-80. [PMID: 24959991 DOI: 10.1021/nl501320a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Vacancy defects in graphene with an odd number of missing atoms, such as the trivacancy, have been imaged at atomic resolution using aberration corrected transmission electron microscopy. These defects are not just stabilized by simple bond reconstructions between under-coordinated carbon atoms, as exhibited by even vacancies such as the divacancy. Instead we have observed reconstructions consisting of under-coordinated bridging carbon atoms spanning the vacancy to saturate edge atoms. We report detailed studies of the effect of this bridging atom on the configuration of the trivacancy and higher order odd number vacancies, as well as its role in defect stabilization in amorphous systems. Theoretical analysis using density functional theory and tight-binding molecular dynamics calculations demonstrate that the bridging atom enables the low energy reconfiguration of these defect structures.
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Affiliation(s)
- Alex W Robertson
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
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202
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Gai PP, Zhao CE, Wang Y, Abdel-Halim ES, Zhang JR, Zhu JJ. NADH dehydrogenase-like behavior of nitrogen-doped graphene and its application in NAD(+)-dependent dehydrogenase biosensing. Biosens Bioelectron 2014; 62:170-6. [PMID: 24999994 DOI: 10.1016/j.bios.2014.06.043] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Revised: 06/17/2014] [Accepted: 06/19/2014] [Indexed: 11/26/2022]
Abstract
A novel electrochemical biosensing platform for nicotinamide adenine dinucleotide (NAD(+))-dependent dehydrogenase catalysis was designed using the nitrogen-doped graphene (NG), which had properties similar to NADH dehydrogenase (CoI). NG mimicked flavin mononucleotide (FMN) in CoI and efficiently catalyzed NADH oxidation. NG also acted as an electron transport "bridge" from NADH to the electrode due to its excellent conductivity. In comparison with a bare gold electrode, an 800 mV decrease in the overpotential for NADH oxidation and CoI-like behavior were observed at NG-modified electrode, which is the largest decrease in overpotential for NADH oxidation reported to date. The catalytic rate constant (k) for the CoI-like behavior of NG was estimated to be 2.3×10(5) M(-1) s(-1), which is much higher than that of other previously reported FMN analogs. The Michaelis-Menten constant (Km) of NG was 26 μM, which is comparable to the Km of CoI (10 μM). Electrodes modified with NG and NG/gold nanoparticals/formate dehydrogenase (NG/AuNPs/FDH) showed excellent analytical performance for the detection of NADH and formate. This electrode fabrication strategy could be used to create a universal biosensing platform for developing NAD(+)-dependent dehydrogenase biosensors and biofuel cells.
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Affiliation(s)
- Pan-Pan Gai
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China
| | - Cui-E Zhao
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China
| | - Ying Wang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China
| | - E S Abdel-Halim
- Petrochemical Research Chair, Chemistry Department, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
| | - Jian-Rong Zhang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China; School of Chemistry and Life Science, Nanjing University Jinling College, Nanjing 210089, PR China.
| | - Jun-Jie Zhu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
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203
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Geng L, Wu S, Zou Y, Jia M, Zhang W, Yan W, Liu G. Correlation between the microstructures of graphite oxides and their catalytic behaviors in air oxidation of benzyl alcohol. J Colloid Interface Sci 2014; 421:71-7. [DOI: 10.1016/j.jcis.2014.01.031] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 01/17/2014] [Accepted: 01/23/2014] [Indexed: 10/25/2022]
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204
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Tan X, Jin P, Chen Z. With the same Clar formulas, do the two-dimensional sandwich nanostructures X-Cr-X (X = C4H, NC3 and BC3) behave similarly? Phys Chem Chem Phys 2014; 16:6002-11. [PMID: 24549363 DOI: 10.1039/c3cp54838d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The "perturbation" effects (i.e. hyperconjugation, electronegativity, and conjugation) on the structural, electronic, and magnetic properties of three kinds of two-dimensional (2D) X-Cr-X (X = C4H, NC3 and BC3 monolayers) sandwich nanostructures were systematically investigated by means of spin-polarized density functional theory (DFT) computations. Although all these 2D sandwich systems energetically prefer the same structural pattern and are featured with the same Clar formulas, their electronic and magnetic properties are significantly influenced by the "perturbations". Especially, a very strong π conjugation through the vacant p orbital of the B atom in BC3 leads to its sandwich structure with antiferromagnetic and conducting characters, which are in stark contrast to the non-magnetic and semiconducting characters of C4H-Cr-C4H and NC3-Cr-NC3. These findings reveal that simple counting Clar formulas alone are insufficient to fully understand the electronic and magnetic properties of graphene-related materials, and more attention should be given to such "perturbation" effects.
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Affiliation(s)
- Xin Tan
- Department of Chemistry, Institute for Functional Nanomaterials, University of Puerto Rico, Rio Piedras Campus, San Juan 00931, Puerto Rico, USA.
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205
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Hu J, Wu R. Giant magnetic anisotropy of transition-metal dimers on defected graphene. NANO LETTERS 2014; 14:1853-1858. [PMID: 24666159 DOI: 10.1021/nl404627h] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Continuous miniaturization of magnetic units in spintronics and quantum computing devices inspires efforts to search for magnetic nanostructures with giant magnetic anisotropy energy (MAE) and high structural stability. Through density functional theory calculations, we found that either Pt-Ir or Os-Ru dimer forms a stable vertical structure on the defected graphene and possess an MAE larger than 60 meV, sufficient for room-temperature applications. Interestingly, their MAEs can be conveniently manipulated by using an external electric field, which makes them excellent magnetic units in spintronics and quantum computing devices.
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Affiliation(s)
- Jun Hu
- Department of Physics and Astronomy, University of California , Irvine, California 92697-4575, United States
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206
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Robertson AW, Lee GD, He K, Yoon E, Kirkland AI, Warner JH. Stability and dynamics of the tetravacancy in graphene. NANO LETTERS 2014; 14:1634-1642. [PMID: 24588782 DOI: 10.1021/nl500119p] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The relative prevalence of various configurations of the tetravacancy defect in monolayer graphene has been examined using aberration corrected transmission electron microscopy (TEM). It was found that the two most common structures are extended linear defect structures, with the 3-fold symmetric Y-tetravacancy seldom imaged, in spite of this being a low energy state. Using density functional theory and tight-binding molecular dynamics calculations, we have determined that our TEM observations support a dynamic model of the tetravacancy under electron irradiation, with Stone-Wales bond rotations providing a mechanism for defect relaxation into lowest energy configurations. The most prevalent tetravacancy structures, while not necessarily having the lowest formation energy, are found to have a local energy minimum in the overall energy landscape for tetravacancies, explaining their relatively high occurrence.
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Affiliation(s)
- Alex W Robertson
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
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207
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Trevethan T, Latham CD, Heggie MI, Briddon PR, Rayson MJ. Vacancy diffusion and coalescence in graphene directed by defect strain fields. NANOSCALE 2014; 6:2978-2986. [PMID: 24487384 DOI: 10.1039/c3nr06222h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The formation of extended defects in graphene from the coalescence of individual mobile vacancies can significantly alter its mechanical, electrical and chemical properties. We present the results of ab initio simulations which demonstrate that the strain created by multi-vacancy complexes in graphene determine their overall growth morphology when formed from the coalescence of individual mobile lattice vacancies. Using density functional theory, we map out the potential energy surface for the motion of mono-vacancies in the vicinity of multi-vacancy defects. The inhomogeneous bond strain created by the multi-vacancy complexes strongly biases the activation energy barriers for single vacancy motion over a wide area. Kinetic Monte Carlo simulations based on rates from ab initio derived activation energies are performed to investigate the dynamical evolution of single vacancies in these strain fields. The resultant coalescence processes reveal that the dominant morphology of multi-vacancy complexes will consist of vacancy lines running in the two primary crystallographic directions, and that more thermodynamically stable structures, such as holes, are kinetically inaccessible from mono-vacancy aggregation alone.
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Affiliation(s)
- Thomas Trevethan
- Department of Chemistry, University of Surrey, Guildford, GU2 7XH, UK.
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208
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Robertson AW, He K, Kirkland AI, Warner JH. Inflating graphene with atomic scale blisters. NANO LETTERS 2014; 14:908-914. [PMID: 24422539 DOI: 10.1021/nl404266k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Using 80 kV electron beam irradiation we have created graphene blister defects of additional carbon atoms incorporated into a graphene lattice. These structures are the antithesis of the vacancy defect with blister defects observed to contain up to six additional carbon atoms. We present aberration-corrected transmission electron microscopy data demonstrating the formation of a blister from an existing divacancy, together with further examples that undergo reconfiguration and annihilation under the electron beam. The relative stability of the observed variations of blister are discussed and considered in the context of previous calculations. It is shown that the blister defect is seldom found in isolation and is more commonly coupled with dislocations where it can act as an intermediate state, permitting dislocation core climb without the atom ejection from the graphene lattice required for nonconservative motion.
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Affiliation(s)
- Alex W Robertson
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
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209
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Zabet-Khosousi A, Zhao L, Pálová L, Hybertsen MS, Reichman DR, Pasupathy AN, Flynn GW. Segregation of Sublattice Domains in Nitrogen-Doped Graphene. J Am Chem Soc 2014; 136:1391-7. [DOI: 10.1021/ja408463g] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Amir Zabet-Khosousi
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Liuyan Zhao
- Department
of Physics, Columbia University, New York, New York 10027, United States
| | - Lucia Pálová
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Mark S. Hybertsen
- Center
for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - David R. Reichman
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Abhay N. Pasupathy
- Department
of Physics, Columbia University, New York, New York 10027, United States
| | - George W. Flynn
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
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210
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Biroju RK, Giri PK, Dhara S, Imakita K, Fujii M. Graphene-assisted controlled growth of highly aligned ZnO nanorods and nanoribbons: growth mechanism and photoluminescence properties. ACS APPLIED MATERIALS & INTERFACES 2014; 6:377-387. [PMID: 24367888 DOI: 10.1021/am404411c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We demonstrate graphene-assisted controlled fabrication of various ZnO 1D nanostructures on the SiO2/graphene substrate at a low temperature (540 °C) and elucidate the growth mechanism. Monolayer and a few layer graphene prepared by chemical vapor deposition (CVD) and subsequently coated with a thin Au layer followed by rapid thermal annealing is shown to result in highly aligned wurtzite ZnO nanorods (NRs) with clear hexagonal facets. On the other hand, direct growth on CVD graphene without a Au catalyst layer resulted in a randomly oriented growth of dense ZnO nanoribbons (NRBs). The role of in-plane defects and preferential clustering of Au atoms on the defect sites of graphene on the growth of highly aligned ZnO NRs/nanowires (NWs) on graphene was established from micro-Raman and high-resolution transmission electron microscopy analyses. Further, we demonstrate strong UV and visible photoluminescence (PL) from the as-grown and post-growth annealed ZnO NRs, NWs, and NRBs, and the origin of the PL emission is correlated well with the X-ray photoelectron spectroscopy analysis. Our results hint toward an epitaxial growth of aligned ZnO NRs on graphene by a vapor-liquid-solid mechanism and establish the importance of defect engineering in graphene for controlled fabrication of graphene-semiconductor NW hybrids with improved optoelectronic functionalities.
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Affiliation(s)
- Ravi K Biroju
- Centre for Nanotechnology, Indian Institute of Technology Guwahati , Guwahati 781039, India
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211
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Impeng S, Khongpracha P, Warakulwit C, Jansang B, Sirijaraensre J, Ehara M, Limtrakul J. Direct oxidation of methane to methanol on Fe–O modified graphene. RSC Adv 2014. [DOI: 10.1039/c3ra47826b] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The reaction mechanisms of the partial oxidation of methane to methanol over FeO/graphene are unraveled using an advanced DFT approach.
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Affiliation(s)
- Sarawoot Impeng
- Department of Chemistry and NANOTEC Center for Nanoscale Materials Design for Green Nanotechnology
- Faculty of Science
- Kasetsart University
- Bangkok 10900, Thailand
- Center for Advanced Studies in Nanotechnology and Its Applications in Chemical
| | - Pipat Khongpracha
- Department of Chemistry and NANOTEC Center for Nanoscale Materials Design for Green Nanotechnology
- Faculty of Science
- Kasetsart University
- Bangkok 10900, Thailand
- Center for Advanced Studies in Nanotechnology and Its Applications in Chemical
| | - Chompunuch Warakulwit
- Department of Chemistry and NANOTEC Center for Nanoscale Materials Design for Green Nanotechnology
- Faculty of Science
- Kasetsart University
- Bangkok 10900, Thailand
- Center for Advanced Studies in Nanotechnology and Its Applications in Chemical
| | - Bavornpon Jansang
- PTT Research and Technology Institute
- PTT Public Company Limited
- Wangnoi, Thailand
| | - Jakkapan Sirijaraensre
- Department of Chemistry and NANOTEC Center for Nanoscale Materials Design for Green Nanotechnology
- Faculty of Science
- Kasetsart University
- Bangkok 10900, Thailand
- Center for Advanced Studies in Nanotechnology and Its Applications in Chemical
| | - Masahiro Ehara
- Institute for Molecular Science and Research Center for Computational Science
- Okazaki 444-8585, Japan
| | - Jumras Limtrakul
- Department of Chemistry and NANOTEC Center for Nanoscale Materials Design for Green Nanotechnology
- Faculty of Science
- Kasetsart University
- Bangkok 10900, Thailand
- Center for Advanced Studies in Nanotechnology and Its Applications in Chemical
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212
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Liu X, Duan T, Sui Y, Meng C, Han Y. Copper atoms embedded in hexagonal boron nitride as potential catalysts for CO oxidation: a first-principles investigation. RSC Adv 2014. [DOI: 10.1039/c4ra06436d] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The embedment in h-BN makes Cu states compatible to reactant states and facilitates the charge transfer for reaction to proceed.
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Affiliation(s)
- Xin Liu
- School of Chemistry
- Dalian University of Technology
- Dalian, China
| | - Ting Duan
- School of Chemistry
- Dalian University of Technology
- Dalian, China
| | - Yanhui Sui
- School of Chemistry
- Dalian University of Technology
- Dalian, China
| | - Changgong Meng
- School of Chemistry
- Dalian University of Technology
- Dalian, China
| | - Yu Han
- Advanced Membranes and Porous Materials Center
- Physical Sciences and Engineering Division
- King Abdullah University of Science and Technology
- Thuwal 23955-6900, Saudi Arabia
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213
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Liu X, Sui Y, Duan T, Meng C, Han Y. CO oxidation catalyzed by Pt-embedded graphene: a first-principles investigation. Phys Chem Chem Phys 2014; 16:23584-93. [DOI: 10.1039/c4cp02106a] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The combination of reactive Pt atoms and defects over graphene makes Pt-embedded graphene a superior catalyst for low-temperature CO oxidation.
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Affiliation(s)
- Xin Liu
- School of Chemistry
- Dalian University of Technology
- Dalian, P. R. China
| | - Yanhui Sui
- School of Chemistry
- Dalian University of Technology
- Dalian, P. R. China
| | - Ting Duan
- School of Chemistry
- Dalian University of Technology
- Dalian, P. R. China
| | - Changong Meng
- School of Chemistry
- Dalian University of Technology
- Dalian, P. R. China
| | - Yu Han
- Advanced Membranes and Porous Materials Center
- King Abdullah University of Science and Technology
- Thuwal, Kingdom of Saudi Arabia
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214
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Plant SR, Cao L, Yin F, Wang ZW, Palmer RE. Size-dependent propagation of Au nanoclusters through few-layer graphene. NANOSCALE 2014; 6:1258-63. [PMID: 24242001 DOI: 10.1039/c3nr04770a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We report the size-dependent propagation of gold nanoclusters through few-layer graphene (FLG). We employ aberration-corrected scanning transmission electron microscopy (STEM) to track the fate of Au55 and Au923 clusters that have been deposited, independently and isoenergetically, onto suspended FLG films using cluster beam deposition. We demonstrate that Au55 clusters penetrate through the FLG, whereas the monodisperse Au923 clusters reside at the surface. Our approach offers a route to the controlled incorporation of dopant nanoparticles and the generation of nanoscale defects in graphene.
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Affiliation(s)
- Simon R Plant
- Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT, UK.
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215
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Yun WS, Lee JD. Unexpected strong magnetism of Cu doped single-layer MoS2 and its origin. Phys Chem Chem Phys 2014; 16:8990-6. [DOI: 10.1039/c4cp00247d] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nonmagnetic Cu substitutes for Mo in a single-layer MoS2 and induces an unexpected strong magnetism.
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Affiliation(s)
- Won Seok Yun
- Department of Emerging Materials Science
- DGIST
- Daegu 711-873, Korea
- Center for X-ray Optics
- Lawrence Berkeley National Laboratory
| | - J. D. Lee
- Department of Emerging Materials Science
- DGIST
- Daegu 711-873, Korea
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216
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Chen XF, Zhu YF, Jiang Q. Utilisation of janus material for controllable formation of graphene p–n junctions and superlattices. RSC Adv 2014. [DOI: 10.1039/c3ra44550j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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217
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Gong C, Robertson AW, He K, Ford C, Watt AAR, Warner JH. Interactions of Pb and Te atoms with graphene. Dalton Trans 2014; 43:7442-8. [DOI: 10.1039/c4dt00143e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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218
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Bangert U, Pierce W, Kepaptsoglou DM, Ramasse Q, Zan R, Gass MH, Van den Berg JA, Boothroyd CB, Amani J, Hofsäss H. Ion implantation of graphene-toward IC compatible technologies. NANO LETTERS 2013; 13:4902-7. [PMID: 24059439 DOI: 10.1021/nl402812y] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Doping of graphene via low energy ion implantation could open possibilities for fabrication of nanometer-scale patterned graphene-based devices as well as for graphene functionalization compatible with large-scale integrated semiconductor technology. Using advanced electron microscopy/spectroscopy methods, we show for the first time directly that graphene can be doped with B and N via ion implantation and that the retention is in good agreement with predictions from calculation-based literature values. Atomic resolution high-angle dark field imaging (HAADF) combined with single-atom electron energy loss (EEL) spectroscopy reveals that for sufficiently low implantation energies ions are predominantly substitutionally incorporated into the graphene lattice with a very small fraction residing in defect-related sites.
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Affiliation(s)
- U Bangert
- School of Materials, The University of Manchester , Manchester M13 9PL, United Kingdom
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219
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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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220
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Robertson AW, Warner JH. Atomic resolution imaging of graphene by transmission electron microscopy. NANOSCALE 2013; 5:4079-93. [PMID: 23595204 DOI: 10.1039/c3nr00934c] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The atomic structure of a material influences its electronic, chemical, magnetic and mechanical properties. Characterising carbon nanomaterials, such as fullerenes, nanotubes and graphene, at the atomic level is challenging due to their chemical reactivity and low atomic mass. Transmission electron microscopy and scanning probe microscopy are two of the leading methods for imaging graphene at the atomic level. Here, we report on recent advances in atomic resolution imaging of graphene using aberration-corrected high resolution transmission electron microscopy and how it has revealed many of the structural deviations from the pristine monolayer form. Structures in graphene such as vacancy defects, edges, grain boundaries, linear chains, impurity dopants, layer number, layer stacking and bond rotations are explored.
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221
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Yang S, Song X, Zhang P, Gao L. Facile synthesis of nitrogen-doped graphene-ultrathin MnO2 sheet composites and their electrochemical performances. ACS APPLIED MATERIALS & INTERFACES 2013; 5:3317-22. [PMID: 23532663 DOI: 10.1021/am400385g] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Nitrogen-doped graphene-ultrathin MnO2 sheet composites (NGMCs) were prepared through a one-step hydrothermal method at low temperature (120 °C). Ultrathin MnO2 sheets were well-dispersed and tightly anchored on graphene sheets, which were doped with nitrogen simultaneously. NGMCs electrode exhibited enhanced capacitive performances relative to those of undoped graphene-ultrathin MnO2 sheets composites (GMCs). As the current density increased from 0.2 to 2 A/g, the capacitance of NGMCs still retained ~74.9%, which was considerablely higher than that of GMCs (27%). Moreover, over 94.2% of the original capacitance was maintained after 2000 cycles, indicating a good cycle stability of NGMCs electrode materials.
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Affiliation(s)
- Shuhua Yang
- State Key Laboratory for Metallic Matrix Composite Materials, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
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222
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Robertson AW, Montanari B, He K, Kim J, Allen CS, Wu YA, Olivier J, Neethling J, Harrison N, Kirkland AI, Warner JH. Dynamics of single Fe atoms in graphene vacancies. NANO LETTERS 2013; 13:1468-1475. [PMID: 23517297 DOI: 10.1021/nl304495v] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Focused electron beam irradiation has been used to create mono and divacancies in graphene within a defined area, which then act as trap sites for mobile Fe atoms initially resident on the graphene surface. Aberration-corrected transmission electron microscopy at 80 kV has been used to study the real time dynamics of Fe atoms filling the vacancy sites in graphene with atomic resolution. We find that the incorporation of a dopant atom results in pronounced displacements of the surrounding carbon atoms of up to 0.5 Å, which is in good agreement with density functional theory calculations. Once incorporated into the graphene lattice, Fe atoms can transition to adjacent lattice positions and reversibly switch their bonding between four and three nearest neighbors. The C atoms adjacent to the Fe atoms are found to be more susceptible to Stone-Wales type bond rotations with these bond rotations associated with changes in the dopant bonding configuration. These results demonstrate the use of controlled electron beam irradiation to incorporate dopants into the graphene lattice with nanoscale spatial control.
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Affiliation(s)
- Alex W Robertson
- Department of Materials, University of Oxford, Oxford, United Kingdom
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223
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Kaukonen M, Krasheninnikov AV, Kauppinen E, Nieminen RM. Doped Graphene as a Material for Oxygen Reduction Reaction in Hydrogen Fuel Cells: A Computational Study. ACS Catal 2013. [DOI: 10.1021/cs300605t] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- M. Kaukonen
- NanoMaterials Group, Department of Applied Physics and Center for
New Materials, Aalto University, P.O. Box
15100, FI- 00076 Aalto, Espoo, Finland
| | - A. V. Krasheninnikov
- COMP/Applied Physics, Aalto University, P.O. Box 1100, FI-00076 Aalto, Finland
- Department of Physics, University of Helsinki, P.O. Box 43, FI-00014 Helsinki, Finland
| | - E. Kauppinen
- NanoMaterials Group, Department of Applied Physics and Center for
New Materials, Aalto University, P.O. Box
15100, FI- 00076 Aalto, Espoo, Finland
| | - R. M. Nieminen
- COMP/Applied Physics, Aalto University, P.O. Box 1100, FI-00076 Aalto, Finland
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224
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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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225
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Luan HX, Zhang CW, Li SS, Zhang RW, Wang PJ. First-principles study on ferromagnetism in W-doped graphene. RSC Adv 2013. [DOI: 10.1039/c3ra44672g] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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226
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Wang H, Li K, Yao Y, Wang Q, Cheng Y, Schwingenschlögl U, Zhang XX, Yang W. Unraveling the atomic structure of ultrafine iron clusters. Sci Rep 2012; 2:995. [PMID: 23251781 PMCID: PMC3524523 DOI: 10.1038/srep00995] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 11/30/2012] [Indexed: 11/30/2022] Open
Abstract
Unraveling the atomic structures of ultrafine iron clusters is critical to understanding their size-dependent catalytic effects and electronic properties. Here, we describe the stable close-packed structure of ultrafine Fe clusters for the first time, thanks to the superior properties of graphene, including the monolayer thickness, chemical inertness, mechanical strength, electrical and thermal conductivity. These clusters prefer to take regular planar shapes with morphology changes by local atomic shuffling, as suggested by the early hypothesis of solid-solid transformation. Our observations differ from observations from earlier experimental study and theoretical model, such as icosahedron, decahedron or cuboctahedron. No interaction was observed between Fe atoms or clusters and pristine graphene. However, preferential carving, as observed by other research groups, can be realized only when Fe clusters are embedded in graphene. The techniques introduced here will be of use in investigations of other clusters or even single atoms or molecules.
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Affiliation(s)
- Hongtao Wang
- Institute of Applied Mechanics, Zhejiang University, Hangzhou 310027, China
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227
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Zhang Z, Liu X, Yakobson BI, Guo W. Two-Dimensional Tetragonal TiC Monolayer Sheet and Nanoribbons. J Am Chem Soc 2012; 134:19326-9. [DOI: 10.1021/ja308576g] [Citation(s) in RCA: 161] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Zhuhua Zhang
- State Key Laboratory of Mechanics
and Control of Mechanical Structures, Key Laboratory of Intelligent
Nano Materials and Devices of MoE and Institute of Nano Science, Nanjing University of Aeronautics and Astronautics,
Nanjing 210016, China
- Department
of Mechanical Engineering
and Materials Science, Rice University,
Houston, Texas 77005, United States
| | - Xiaofei Liu
- State Key Laboratory of Mechanics
and Control of Mechanical Structures, Key Laboratory of Intelligent
Nano Materials and Devices of MoE and Institute of Nano Science, Nanjing University of Aeronautics and Astronautics,
Nanjing 210016, China
| | - Boris I. Yakobson
- Department
of Mechanical Engineering
and Materials Science, Rice University,
Houston, Texas 77005, United States
| | - Wanlin Guo
- State Key Laboratory of Mechanics
and Control of Mechanical Structures, Key Laboratory of Intelligent
Nano Materials and Devices of MoE and Institute of Nano Science, Nanjing University of Aeronautics and Astronautics,
Nanjing 210016, China
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228
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Gross L, Mohn F, Moll N, Schuler B, Criado A, Guitián E, Peña D, Gourdon A, Meyer G. Bond-order discrimination by atomic force microscopy. Science 2012; 337:1326-9. [PMID: 22984067 DOI: 10.1126/science.1225621] [Citation(s) in RCA: 284] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We show that the different bond orders of individual carbon-carbon bonds in polycyclic aromatic hydrocarbons and fullerenes can be distinguished by noncontact atomic force microscopy (AFM) with a carbon monoxide (CO)-functionalized tip. We found two different contrast mechanisms, which were corroborated by density functional theory calculations: The greater electron density in bonds of higher bond order led to a stronger Pauli repulsion, which enhanced the brightness of these bonds in high-resolution AFM images. The apparent bond length in the AFM images decreased with increasing bond order because of tilting of the CO molecule at the tip apex.
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Affiliation(s)
- Leo Gross
- IBM Research-Zurich, CH-8803 Rüschlikon, Switzerland.
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229
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Hashimoto A, Takeguchi M. In situ observation of Pt nanoparticles on graphene layers under high temperature using aberration-corrected transmission electron microscopy. Microscopy (Oxf) 2012; 61:409-13. [DOI: 10.1093/jmicro/dfs060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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230
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Zhu W, Wang H, Yang W. Evolution of graphene nanoribbons under low-voltage electron irradiation. NANOSCALE 2012; 4:4555-4561. [PMID: 22699261 DOI: 10.1039/c2nr30648d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Though the all-semiconducting nature of ultrathin graphene nanoribbons (GNRs) has been demonstrated in field-effect transistors operated at room temperature with ∼10(5) on-off current ratios, the borderline for the potential of GNRs is still untouched. There remains a great challenge in fabricating even thinner GNRs with precise width, known edge configurations and specified crystallographic orientations. Unparalleled to other methods, low-voltage electron irradiation leads to a continuous reduction in width to a sub-nanometer range until the occurrence of structural instability. The underlying mechanisms have been investigated by the molecular dynamics method herein, combined with in situ aberration-corrected transmission electron microscopy and density functional theory calculations. The structural evolution reveals that the zigzag edges are dynamically more stable than the chiral ones. Preferential bond breaking induces atomic rings and dangling bonds as the initial defects. The defects grow, combine and reconstruct to complex edge structures. Dynamic recovery is enhanced by thermal activation, especially in cooperation with electron irradiation. Roughness develops under irradiation and reaches a plateau less than 1 nm for all edge configurations after longtime exposure. These features render low-voltage electron irradiation an attractive technique in the fabrication of ultrathin GNRs for exploring the ultimate electronic properties.
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Affiliation(s)
- Wenpeng Zhu
- AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China
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231
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Yumura T, Awano T, Kobayashi H, Yamabe T. Platinum clusters on vacancy-type defects of nanometer-sized graphene patches. Molecules 2012; 17:7941-60. [PMID: 22751260 PMCID: PMC6268068 DOI: 10.3390/molecules17077941] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 06/11/2012] [Accepted: 06/19/2012] [Indexed: 11/16/2022] Open
Abstract
Density functional theory calculations found that spin density distributions of platinum clusters adsorbed on nanometer-size defective graphene patches with zigzag edges deviate strongly from those in the corresponding bare clusters, due to strong Pt-C interactions. In contrast, platinum clusters on the pristine patch have spin density distributions similar to the bare cases. The different spin density distributions come from whether underlying carbon atoms have radical characters or not. In the pristine patch, center carbon atoms do not have spin densities, and they cannot influence radical characters of the absorbed cluster. In contrast, radical characters appear on the defective sites, and thus spin density distributions of the adsorbed clusters are modulated by the Pt-C interactions. Consequently, characters of platinum clusters adsorbed on the sp² surface can be changed by introducing vacancy-type defects.
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Affiliation(s)
- Takashi Yumura
- Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
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232
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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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233
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Abstract
Graphene has captured the imagination of researchers worldwide as an ideal two-dimensional material with exceptional electrical transport properties. The high electron and hole mobility quickly inspired scientists to search for electronic applications that require high-performance channel materials. However, the absence of a bandgap in graphene immediately revealed itself in terms of ambipolar device characteristics and the nonexistence of a device off-state. The question is: How can the superior electronic properties of graphene be harvested while dealing appropriately with its unique characteristics rather than enforcing conventional device concepts? Here, we report a novel device idea, a graphene-based frequency tripler, an application that employs an innovative electrostatic doping approach and exploits the unique ambipolar behavior of graphene.
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Affiliation(s)
- Hong-Yan Chen
- School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA.
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234
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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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235
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Tang Y, Yang Z, Dai X. A theoretical simulation on the catalytic oxidation of CO on Pt/graphene. Phys Chem Chem Phys 2012; 14:16566-72. [DOI: 10.1039/c2cp41441d] [Citation(s) in RCA: 269] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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236
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Palaniselvam T, Aiyappa HB, Kurungot S. An efficient oxygen reduction electrocatalyst from graphene by simultaneously generating pores and nitrogen doped active sites. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm35128e] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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