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Journal articles on the topic 'Graphene Quantum Sheets'

Author: Grafiati

Published: 7 September 2023

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1

Flouris, Kyriakos, Miller Mendoza Jimenez, and Hans J. Herrmann. "Landau levels in wrinkled and rippled graphene sheets." International Journal of Modern Physics C 30, no. 10 (October 2019): 1941006. http://dx.doi.org/10.1142/s0129183119410067.

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We study the discrete energy spectrum of curved graphene sheets in the presence of a magnetic field. The shifting of the Landau levels is determined for complex and realistic geometries of curved graphene sheets. The energy levels follow a similar square root dependence on the energy quantum number as for rippled and flat graphene sheets. The Landau levels are shifted towards lower energies proportionally to the average deformation and the effect is larger compared to a simple uni-axially rippled geometry. Furthermore, the resistivity of wrinkled graphene sheets is calculated for different average space curvatures and shown to obey a linear relation. The study is carried out with a quantum lattice Boltzmann method, solving the Dirac equation on curved manifolds.

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2

Klimchitskaya, Galina L., and Vladimir M. Mostepanenko. "Casimir and Casimir-Polder Forces in Graphene Systems: Quantum Field Theoretical Description and Thermodynamics." Universe 6, no. 9 (September 9, 2020): 150. http://dx.doi.org/10.3390/universe6090150.

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We review recent results on the low-temperature behaviors of the Casimir-Polder and Casimir free energy an entropy for a polarizable atom interacting with a graphene sheet and for two graphene sheets, respectively. These results are discussed in the wide context of problems arising in the Lifshitz theory of van der Waals and Casimir forces when it is applied to metallic and dielectric bodies. After a brief treatment of different approaches to theoretical description of the electromagnetic response of graphene, we concentrate on the derivation of response function in the framework of thermal quantum field theory in the Matsubara formulation using the polarization tensor in (2 + 1)-dimensional space—time. The asymptotic expressions for the Casimir-Polder and Casimir free energy and entropy at low temperature, obtained with the polarization tensor, are presented for a pristine graphene as well as for graphene sheets possessing some nonzero energy gap Δ and chemical potential μ under different relationships between the values of Δ and μ. Along with reviewing the results obtained in the literature, we present some new findings concerning the case μ≠0, Δ=0. The conclusion is made that the Lifshitz theory of the Casimir and Casimir-Polder forces in graphene systems using the quantum field theoretical description of a pristine graphene, as well as real graphene sheets with Δ>2μ or Δ<2μ, is consistent with the requirements of thermodynamics. The case of graphene with Δ=2μ≠0 leads to an entropic anomaly, but is argued to be physically unrealistic. The way to a resolution of thermodynamic problems in the Lifshitz theory based on the results obtained for graphene is discussed.

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3

Wang, Jigang, Ji Zhou, Wenhua Zhou, Jilong Shi, Lun Ma, Wei Chen, Yongsheng Wang, Dawei He, Ming Fu, and Yongna Zhang. "Synthesis, Photoluminescence and Bio-Targeting Applications of Blue Graphene Quantum Dots." Journal of Nanoscience and Nanotechnology 16, no. 4 (April 1, 2016): 3457–67. http://dx.doi.org/10.1166/jnn.2016.11817.

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Chemical derived graphene oxide, an atomically thin sheet of graphite with two-dimensional construction, offers interesting physical, electronic, thermal, chemical, and mechanical properties that are currently being explored for advanced physics electronics, membranes, and composites. Herein, we study graphene quantum dots (GQD) with the blue photoluminescence under various parameters. The GQD samples were prepared at different temperatures, and the blue photoluminescence intensity of the solution improved radically as the heating temperatures increased. Concerning PL peak and intensity of the quantum dots, the results demonstrated dependence on time under heating, temperature of heating, and pH adjusted by the addition of sodium hydroxide. After hydrothermal synthesis routes, the functional groups of graphene oxide were altered the morphology showed the stacking configuration, and self-assembled structure of the graphene sheets with obvious wrinkles appeared at the edge structures. In addition, absorption, PL, and PLE spectra of the graphene quantum dots increase with different quantities of sodium hydroxide added. Finally, using GQD to target PNTIA cells was carried out successfully. High uptake efficiency and no cytotoxic effects indicate graphene quantum dots can be suitable for bio-targeting.

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4

Hassanien, Ahmed S., Radwa A. Shedeed, and Nageh K. Allam. "Graphene Quantum Sheets with Multiband Emission: Unravelling the Molecular Origin of Graphene Quantum Dots." Journal of Physical Chemistry C 120, no. 38 (September 13, 2016): 21678–84. http://dx.doi.org/10.1021/acs.jpcc.6b07593.

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5

Kanodarwala, Fehmida K., Fan Wang, Peter J. Reece, and John A. Stride. "Deposition of CdSe quantum dots on graphene sheets." Journal of Luminescence 146 (February 2014): 46–52. http://dx.doi.org/10.1016/j.jlumin.2013.08.072.

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6

Flouris, Kyriakos, Sauro Succi, and Hans J. Herrmann. "Quantized Alternate Current on Curved Graphene." Condensed Matter 4, no. 2 (April 9, 2019): 39. http://dx.doi.org/10.3390/condmat4020039.

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Based on the numerical solution of the Quantum Lattice Boltzmann Method in curved space, we predicted the onset of a quantized alternating current on curved graphene sheets. This numerical prediction was verified analytically via a set of semi-classical equations that related the Berry curvature to real space curvature. The proposed quantized oscillating current on curved graphene could form the basis for the implementation of quantum information-processing algorithms.

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7

Sim, Uk, Joonhee Moon, Junghyun An, Jin Hyoun Kang, Sung Eun Jerng, Junsang Moon, Sung-Pyo Cho, Byung Hee Hong, and Ki Tae Nam. "N-doped graphene quantum sheets on silicon nanowire photocathodes for hydrogen production." Energy & Environmental Science 8, no. 4 (2015): 1329–38. http://dx.doi.org/10.1039/c4ee03607g.

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8

Zeng, Minxiang, Xuezhen Wang, Yi-Hsien Yu, Lecheng Zhang, Wakaas Shafi, Xiayun Huang, and Zhengdong Cheng. "The Synthesis of Amphiphilic Luminescent Graphene Quantum Dot and Its Application in Miniemulsion Polymerization." Journal of Nanomaterials 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/6490383.

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Although emulsion applications of microscale graphene sheets have attracted much attention recently, nanoscale graphene platelets, namely, graphene quantum dots (GQDs), have been rarely explored in interface science. In this work, we study the interfacial behaviors and emulsion phase diagrams of hydrophobic-functionalized graphene quantum dots (C18-GQDs). Distinctive from pristine graphene quantum dots (p-GQDs), C18-GQDs show several interesting surface-active properties including high emulsification efficiency in stabilizing dodecane-in-water emulsions. We then utilize the C18-GQDs as surfactants in miniemulsion polymerization of styrene, achieving uniform and relatively small polystyrene nanospheres. The high emulsification efficiency, low production cost, uniform morphology, intriguing photoluminescence, and extraordinary stability render C18-GQDs an attractive alternative in surfactant applications.

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9

Dehestani, Maryam, Leila Zeidabadinejad, and Sedigheh Pourestarabadi. "QTAIM investigations of decorated graphyne and boron nitride for Li detection." Journal of the Serbian Chemical Society 82, no. 3 (2017): 289–301. http://dx.doi.org/10.2298/jsc160725012d.

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The interactions between thirteen Li atoms and graphyne (GY) and boron nitride (BN-yne) were investigated by the density functional theory (DFT). The electronic and structural properties of the interactions between the hollow sites of GY and BN-yne with Li atoms were unveiled within the quantum theory of atoms in molecules (QTAIM) framework. Theoretical understanding of the interactions between Li atoms and extended carbon-based network structures is crucial for the development of new materials. Herein, calculations to explore the impact of Li decoration on the GY and BN-yne are reported. It was predicted that Li decoration would increase the density of state of these sheets. Owing to strong interactions between Li and the GY and BNyne, dramatic changes in the electronic properties of the sheets together with large band gap variations have been observed. The present study sheds deep insight into the chemical properties of the novel carbon?based two-dimensional (2D) structures beyond the graphene sheet.

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10

Govindhan, Maduraiveeran, Brennan Mao, and Aicheng Chen. "Novel cobalt quantum dot/graphene nanocomposites as highly efficient electrocatalysts for water splitting." Nanoscale 8, no. 3 (2016): 1485–92. http://dx.doi.org/10.1039/c5nr06726j.

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11

Min, Misook, Gustavo A. Saenz, and Anupama B. Kaul. "Optoelectronic properties of graphene quantum dots with molybdenum disulfide." MRS Advances 4, no. 10 (2019): 615–20. http://dx.doi.org/10.1557/adv.2019.50.

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ABSTRACTThe presence of a direct optical bandgap in the transition metal dichalcogenide (TMD) layers leads to promising applications in optoelectronic devices such as phototransistors and photodetectors. These devices are commonly fabricated using few-layer and monolayer MoS2 sheets obtained using mechanical exfoliation or chemical vapor deposition techniques. The hybrid structure of quantum dots (QDs) and 2D materials has been investigated to provide outstanding properties for various applications. Herein we report the fabrication of a hybrid QDs/MoS2 photodetector consisting of graphene quantum dots (GQDs) and multilayer MoS2 sheets. The hybrid GQDs and MoS2 films are characterized by atomic force microscopy (AFM); additionally, the I-V characteristics are measured by two-point probe station.

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12

Ryu, Jaehoon, Eunwoo Lee, Seungae Lee, and Jyongsik Jang. "Fabrication of graphene quantum dot-decorated graphene sheets via chemical surface modification." Chem. Commun. 50, no. 98 (October 31, 2014): 15616–18. http://dx.doi.org/10.1039/c4cc06567k.

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13

Pan, Dengyu, Jingchun Zhang, Zhen Li, and Minghong Wu. "Hydrothermal Route for Cutting Graphene Sheets into Blue-Luminescent Graphene Quantum Dots." Advanced Materials 22, no. 6 (February 9, 2010): 734–38. http://dx.doi.org/10.1002/adma.200902825.

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14

Hoang, Thi Thu, Hoai Phuong Pham, and Quang Trung Tran. "A Facile Microwave-Assisted Hydrothermal Synthesis of Graphene Quantum Dots for Organic Solar Cell Efficiency Improvement." Journal of Nanomaterials 2020 (February 11, 2020): 1–8. http://dx.doi.org/10.1155/2020/3207909.

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Carbon-based nanomaterials have successively remained at the forefront of different research fields and applications for years. Understanding of low-dimension carbon material family (CNT, fullerenes, graphene, and graphene quantum dots) has arrived at a certain extension. In this report, graphene quantum dots were synthesized from graphene oxide with a microwave-assisted hydrothermal method. Compared with conventional time-consuming hydrothermal routes, this novel method requires a much shorter time, around ten minutes. Successful formation of quantum dots derived from graphene sheets was verified with microscopic and spectroscopic characterization. Nanoparticles present a diameter of about 2-8 nm, blue emission under ultraviolet excitation, and good dispersion in polar solvents and can be collected in powder form. The synthesized graphene quantum dots were utilized as a hole transport layer in organic solar cells to enhance the cell quantum efficiency. Such quantum dots possess energy levels (Ec and Ev) relevant to HOMO and LUMO levels of conductive polymers. Mixing P3HT:PCBM polymer and graphene quantum dots of sufficient extent notably helps reduce potential difference at interfaces of the two materials. Overall efficiency consequently advances to 1.43%, an increase of more than 44% compared with pristine cells (0.99%).

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15

Gupta, Sanju, Jared Walden, Alexander Banaszak, and Sara B. Carrizosa. "Facile Synthesis of Water-Soluble Graphene Quantum Dots/Graphene for Efficient Photodetector." MRS Advances 3, no. 15-16 (2018): 817–24. http://dx.doi.org/10.1557/adv.2018.14.

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ABSTRACTGraphene quantum dots (GQDs) are zero-dimensional material with characteristics derived from functionalized graphene precursors are graphene sheets a few nanometers in the lateral dimension having a several-layer thickness. Combining the structure of graphene with the quantum confinement and edge effects, GQDs possess unique chemical behavior and physical properties. Intense research activity in GQDs is attributed to their novel phenomena of charge transport and light absorption and photoluminescence excitation. The optical transitions are known to be available up to 6 eV in GQDs, applicable for ultraviolet photonics and optoelectronics devices, biomedical imaging capabilities and technologies. We present facile hydrothermal and solvothermal methods for synthesizing homogenous dispersed and uniform sized GQDs with a strong greenish and violet blue emission peaks at ∼10-14% yield. This approach enabled a large-scale production of aqueous GQD dispersions without the need for chemical stabilizers. The structure and emission mechanism of the GQDs have been studied by combining extensive characterization techniques and rigorous control experiments. We further demonstrate the distinctive advantages of such GQDs as high-performance photodetectors (PDs). Here we also report high-efficient photocurrent (PC) behaviors consisting of multilayer GQDs sandwiched between monolayer graphene sheets. It is conceivable that the observed unique PD characteristics proved to be dominated by tunneling of charge carriers which occurs through the multiple energy states within the bandgap of GQDs, based on bias-dependent variation of the band profiles. This results in novel dark current and PC behaviors. The external quantum efficiency (η) is predicted to be 47% at applied potential 2 V. These findings highlight rich photophysics and comparable performance of graphene/graphene oxide hybrids opening up potential applications as optoelectronic devices.

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16

Sim, Uk, Joonhee Moon, Junghyun An, Jin Hyoun Kang, Sung Eun Jerng, Junsang Moon, Sung-Pyo Cho, Byung Hee Hong, and Ki Tae Nam. "Correction: N-doped graphene quantum sheets on silicon nanowire photocathodes for hydrogen production." Energy & Environmental Science 8, no. 5 (2015): 1626. http://dx.doi.org/10.1039/c5ee90012c.

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17

Li, Junwen, and Vivek B. Shenoy. "Graphene quantum dots embedded in hexagonal boron nitride sheets." Applied Physics Letters 98, no. 1 (January 3, 2011): 013105. http://dx.doi.org/10.1063/1.3533804.

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18

Xu, Yuanqing, Jinquan Chang, Cheng Liang, Xinyu Sui, Yanhong Ma, Luting Song, Wenyu Jiang, et al. "Tailoring Multi-Walled Carbon Nanotubes into Graphene Quantum Sheets." ACS Applied Materials & Interfaces 12, no. 42 (September 28, 2020): 47784–91. http://dx.doi.org/10.1021/acsami.0c11702.

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19

Saha, Shyamal K., Moni Baskey, and Dipanwita Majumdar. "Graphene Quantum Sheets: A New Material for Spintronic Applications." Advanced Materials 22, no. 48 (October 21, 2010): 5531–36. http://dx.doi.org/10.1002/adma.201003300.

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20

de Oliveira, César R., and Vinícius L. Rocha. "Dirac cones for graph models of multilayer AA-stacked graphene sheets." Zeitschrift für Naturforschung A 76, no. 4 (February 15, 2021): 371–84. http://dx.doi.org/10.1515/zna-2020-0330.

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Abstract We propose an extension, of a quantum graph model for a single sheet of graphene, to multilayer AA-stacked graphene and also to a model of the bulk graphite. Spectra and Dirac cones are explicitly characterized for bilayer and trilayer graphene, as well as for graphite. For weak layer interaction (as proposed in the text), simple perturbation arguments also cover any number of layers and it mathematically recovers basic cone existences from the theoretical and experimental physics literature; its main strength is its simplicity.

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21

Poklonski, N. A., S. V. Ratkevich, S. A. Vyrko, A. T. Vlassov, and Nguyen Ngoc Hieu. "Quantum Chemical Calculation of Reactions Involving C20, C60, Graphene and H2O." International Journal of Nanoscience 18, no. 03n04 (March 26, 2019): 1940008. http://dx.doi.org/10.1142/s0219581x19400088.

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Calculations of chemical reactions between C20, C60, hydrogen and water molecules are carried out using the PM3 method. Reactions with a hydrogen release at room temperature and atmospheric pressure are identified by the Gibbs energy change. The hydrogen release can be raised by increasing the number of water molecules in chlorine-assisted decomposition of fullerenes. Calculations of the Gibbs energy of chemical reactions involving water molecules between two parallel curved graphene sheets are carried out using DFT with the functional UB3LYP. During pumping between plates of an electric capacitor designed from curved graphene sheets, the water vapor with the assistance of external illumination is enriched by electrically neutral hydroxyl groups (OH)0.

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22

Tan, Qingke, Xiangli Kong, Xianggang Guan, Chao Wang, and Binghui Xu. "Crystallization of zinc oxide quantum dots on graphene sheets as an anode material for lithium ion batteries." CrystEngComm 22, no. 2 (2020): 320–29. http://dx.doi.org/10.1039/c9ce01285k.

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23

Armaghani, Sahar, Ali Rostami, and Peyman Mirtaheri. "Graphene Nanoribbon Bending (Nanotubes): Interaction Force between QDs and Graphene." Coatings 12, no. 9 (September 15, 2022): 1341. http://dx.doi.org/10.3390/coatings12091341.

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Carbon materials in different shapes—such as fullerene molecules (0D), nanotubes and graphene nanoribbons (1D), graphene sheets (2D), and nanodiamonds (3D)—each have distinct electrical and optical properties. All graphene-based nanostructures are expected to exhibit extraordinary electronic, thermal, and mechanical properties. Moreover, they are therefore promising candidates for a wide range of nanoscience and nanotechnology applications. In this work, we theoretically studied and analyzed how an array of quantum dots affects a charged graphene plate. To that end, the array of quantum dots was embedded on the graphene plate. Then, considering the interaction between QDs and graphene nanoribbons, we transformed the charged plate of a graphene capacitor into a nanotube using the bipolar-induced interaction and the application of an external electromagnetic field. In this work, the dimensions of the graphene plate were 40 nm × 3100 nm. The bending process of a charged graphene plate is controlled by the induced force due to the applied electromagnetic field and the electric field induced by the quantum dots. Finally, using the predetermined frequency and amplitude of the electromagnetic field, the graphene nanoribbon was converted into a graphene nanotube. Since the electrical and optical properties of nanotubes are different from those of graphene plates, this achievement has many practical potential applications in the electro-optical industry.

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24

Liu, Jia Hui, Rong Sheng Li, Binfang Yuan, Jian Wang, Yuan Fang Li, and Cheng Zhi Huang. "Mitochondria-targeting single-layered graphene quantum dots with dual recognition sites for ATP imaging in living cells." Nanoscale 10, no. 36 (2018): 17402–8. http://dx.doi.org/10.1039/c8nr06061d.

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Single-layered graphene quantum dots with dual recognition sites including π-conjugated single sheets and positively charged sites were developed and used for monitoring the mitochondrial ATP fluctuation in living cells.

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25

Fang, Tian, Aniruddha Konar, Huili Xing, and Debdeep Jena. "Carrier statistics and quantum capacitance of graphene sheets and ribbons." Applied Physics Letters 91, no. 9 (August 27, 2007): 092109. http://dx.doi.org/10.1063/1.2776887.

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26

Jin, Yinhua, Hongyi Qin, Jang Ah Kim, Sun-Young Kim, Hyeong-U. Kim, Yong Taik Lim, Taesung Kim, Atul Kulkarni, and Dongbin Kim. "High-Purity Amino-Functionalized Graphene Quantum Dots Derived from Graphene Hydrogel." Nano 11, no. 12 (December 2016): 1650138. http://dx.doi.org/10.1142/s1793292016501381.

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The unique properties of graphene quantum dots (GQDs) make them interesting candidate materials for innovative applications. Herein, we report a facile method to synthesize amino-functionalized graphene quantum dots (AF-GQDs) by a hydrothermal reaction. Graphene oxide (GO) was synthesized by Hummer’s method where ultra-small GO sheets were obtained by a prolonged oxidation process followed by sonication using an ultrasonic probe. Subsequently, graphene hydrogel (GH) was also obtained by a hydrothermal synthesis method. Proper care was taken during synthesis to avoid contamination from water soluble impurities, which are present in the precursor, GO solution. Following the treatment of GH in ammonia, ultra-small amino-functionalized graphene fragments (AF-GQDs) were formed, which detached from the GH to eventually disperse evenly in the water without agglomerating. This modified synthesis process enables the formation of high-purity AF-GQDs (99.14%) while avoiding time-consuming synthesis procedures. Our finding shows that AF-GQDs with sizes less than 5[Formula: see text]nm were well dispersed. A strong photoluminescence (PL) emission at [Formula: see text]410[Formula: see text]nm with 10% PL quantum yield was also observed. These AF-GQDs can be used in many bio applications in view of their low cytotoxicity and strong fluorescence that can be applied to cell imaging.

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27

Klimchitskaya, Galina L., Constantine C. Korikov, Vladimir M. Mostepanenko, and Oleg Yu Tsybin. "Impact of Mass-Gap on the Dispersion Interaction of Nanoparticles with Graphene out of Thermal Equilibrium." Applied Sciences 13, no. 13 (June 25, 2023): 7511. http://dx.doi.org/10.3390/app13137511.

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We consider the nonequilibrium dispersion force acting on nanoparticles on the source side of a gapped graphene sheet. Nanoparticles are kept at the environmental temperature, whereas the graphene sheet may be either cooler or hotter than the environment. Calculation of the dispersion force as a function of separation at different values of the mass-gap parameter is performed using the generalization of the fundamental Lifshitz theory to out-of-thermal-equilibrium conditions. The response of the gapped graphene to quantum and thermal fluctuations in the electromagnetic field is described by the polarization tensor in (2+1)-dimensional space–time in the framework of the Dirac model. The explicit expressions for the components of this tensor in the area of evanescent waves are presented. The nontrivial impact of the mass-gap parameter of graphene on the nonequilibrium dispersion force, as compared to the equilibrium one, is determined. It is shown that, unlike the case of pristine graphene, the nonequilibrium force preserves an attractive character. The possibilities of using the obtained results in the design of micro- and nanodevices, incorporating nanoparticles and graphene sheets for their functionality, is discussed.

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28

Yang, S. Y., A. Díez-Carlón, J. Díez-Mérida, A. Jaoui, I. Das, G. Di Battista, R. Luque-Merino, R. Mech, and Dmitri K. Efetov. "Plethora of many body ground states in magic angle twisted bilayer graphene." Low Temperature Physics 49, no. 6 (June 1, 2023): 631–39. http://dx.doi.org/10.1063/10.0019420.

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The discovery of magic angle twisted bilayer graphene (MATBG), in which two sheets of monolayer graphene are precisely stacked at a specific angle, has opened up a plethora of grand new opportunities in the field of topology, superconductivity, strange metal, and other strongly correlated effects. This review will focus on the various forms of quantum phases in MATBG revealed through quantum transport measurements. The goal is to highlight the uniqueness and current understanding of the various phases, especially how electronic interaction plays a role in them, as well as open questions in regard to the phase diagram.

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29

Banerjee, Sangam, and Dhananjay Bhattacharyya. "Electronic properties of nano-graphene sheets calculated using quantum chemical DFT." Computational Materials Science 44, no. 1 (November 2008): 41–45. http://dx.doi.org/10.1016/j.commatsci.2008.01.044.

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30

Huang, J., L.-W. Guo, Z.-L. Li, L.-L. Chen, J.-J. Lin, Y.-P. Jia, W. Lu, Y. Guo, and X.-L. Chen. "Anisotropic quantum transport in a network of vertically aligned graphene sheets." Journal of Physics: Condensed Matter 26, no. 34 (August 4, 2014): 345301. http://dx.doi.org/10.1088/0953-8984/26/34/345301.

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31

Tulegenova, Malika, Arkady Ilyin, Nazim Guseinov, Gary Beall, and Tilek Kuanyshbekov. "Computer Simulation of the Effect of Structural Defects on the Effectiveness of the Graphene's Protective Properties." Journal of Computational and Theoretical Nanoscience 16, no. 2 (February 1, 2019): 351–54. http://dx.doi.org/10.1166/jctn.2019.8020.

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Graphene has excellent barrier properties, but in practice it is almost impossible to obtain perfect defect-free graphene. In this paper, we carried out theoretical studies of the protective properties of a graphene coating containing structural defects (vacancies and vacancy complexes) and discontinuities (gaps between graphene sheets) from oxygen penetration. Computer models were created and quantum mechanical numerical calculations were performed for a more detailed study and prediction of the studied nanoconstructions properties, using the well-tested DFT-Dmol3 method, widely used by researchers in the physics of nanomaterials and materials science. The results of calculations indicate the high efficiency of the protective action of graphene coating containing structural defects and discontinuities against oxygen penetration.

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32

Pan, Dengyu, Lei Guo, Jingchun Zhang, Chen Xi, Qi Xue, He Huang, Jinghui Li, et al. "Cutting sp2 clusters in graphene sheets into colloidal graphene quantum dots with strong green fluorescence." Journal of Materials Chemistry 22, no. 8 (2012): 3314. http://dx.doi.org/10.1039/c2jm16005f.

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33

Son, Dong Ick, Byoung Wook Kwon, Hong-Hee Kim, Dong Hee Park, Basavaraj Angadi, and Won Kook Choi. "Chemical exfoliation of pure graphene sheets from synthesized ZnO–graphene quasi core–shell quantum dots." Carbon 59 (August 2013): 289–95. http://dx.doi.org/10.1016/j.carbon.2013.03.021.

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34

Moon, Joonhee, Junghyun An, Uk Sim, Sung-Pyo Cho, Jin Hyoun Kang, Chul Chung, Jung-Hye Seo, Jouhahn Lee, Ki Tae Nam, and Byung Hee Hong. "One-Step Synthesis of N-doped Graphene Quantum Sheets from Monolayer Graphene by Nitrogen Plasma." Advanced Materials 26, no. 21 (March 24, 2014): 3501–5. http://dx.doi.org/10.1002/adma.201306287.

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35

Hameed, Riad M., Ahmad Al-Haddad, and Abbas K. H. Albarazanchi. "Influence of Graphene Sheets Accumulation on Optical Band Gap Enhanced Graphite Exfoliation." Al-Mustansiriyah Journal of Science 33, no. 4 (December 30, 2022): 168–74. http://dx.doi.org/10.23851/mjs.v33i4.1216.

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Recently, graphene has been adopted to replace other expansive materials in various devices that perform numerous functionalities in many industrial fields. Meanwhile, researchers are still investigating the amazing properties of graphene. Herein, reduced graphene oxide (rGO) has been successfully exfoliated directly using a graphite rod in a modified electrolyte including a table salt as a co-electrolyte. The structure of graphene obtained by using exfoliation methods shows a low ratio of O/C and confirms the high crystallinity of rGO. The thickness of rGO was adjusted during the drying of the drops of rGO solution and obtained about an 8-80 nm rGO thick. The increased O/C ratio and crystallinity enhancement could be attributed to the quantum confinement effect. Further investigations to estimate the decay constant of the optical band gap during the thinning of the rGO layers show that the optical band gap was associated with thicknesses of the rGO at a decay constant of 0.3367±0.00205. These results would be crucial in several optical applications that depend on the thicknesses and the band gap.

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36

Yang, Yang, Fangcai Zheng, Guoliang Xia, Zhengyan Lun, and Qianwang Chen. "Experimental and theoretical investigations of nitro-group doped porous carbon as a high performance lithium-ion battery anode." Journal of Materials Chemistry A 3, no. 36 (2015): 18657–66. http://dx.doi.org/10.1039/c5ta05676d.

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The lithium adsorption abilities of various functional groups (NH₂, NO₂, SO₃H, Cl, Br, I) are studied by first-principles quantum chemical calculations which are doped at the edge of graphene sheets. Among all the groups, the nitro-group shows the best properties.

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37

Koutsioukis, Apostolos, Konstantinos Spyrou, Nikolaos Chalmpes, Dimitrios Gournis, and Vasilios Georgakilas. "Hydrothermal Unzipping of Multiwalled Carbon Nanotubes and Cutting of Graphene by Potassium Superoxide." Nanomaterials 12, no. 3 (January 28, 2022): 447. http://dx.doi.org/10.3390/nano12030447.

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The dual use of potassium superoxide (KO2) to unzip multiwalled carbon nanotubes (MWCNTs) and cut graphene under hydrothermal conditions is described in this work. The KO2-assisted hydrothermal treatment was proven to be a high-yield method for forming graphene nanoribbons and dots or sub-micro-sized graphene nanosheets. Starting with functionalized MWCNTs, the method produces water-dispersible graphene nanoribbons with characteristic photoluminescence depending on their width. Using pristine graphene, the hydrothermal treatment with KO2 produces nanosized graphene sheets and graphene quantum dots with diameters of less than 10 nm. The latter showed a bright white photoluminescence. The effective hydrothermal unzipping of MWNTs and the cutting of large graphene nanosheets is a valuable top-down approach for the preparation of graphene nanoribbons and small nanographenes. Both products with limited dimensions have interesting applications in nanoelectronics and bionanotechnology.

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38

Ghaeidamini, Marziyeh, David Bernson, Nima Sasanian, Ranjeet Kumar, and Elin K. Esbjörner. "Graphene oxide sheets and quantum dots inhibit α-synuclein amyloid formation by different mechanisms." Nanoscale 12, no. 37 (2020): 19450–60. http://dx.doi.org/10.1039/d0nr05003b.

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39

Pourhashem, Sepideh, Alimorad Rashidi, and Mohammad Reza Vaezi. "Comparing the corrosion protection performance of graphene nanosheets and graphene quantum dots as nanofiller in epoxy coatings." Industrial Lubrication and Tribology 71, no. 5 (July 8, 2019): 653–56. http://dx.doi.org/10.1108/ilt-05-2018-0186.

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Purpose In this research, the effect of graphene nanosheets and graphene quantum dots (GQDs) as carbon-based nanofillers on corrosion protection performance of epoxy coatings is considered. Design/methodology/approach Graphene nanosheets are synthesized via chemical vapor deposition method, and GQDs are synthesized by a simple and gram scale procedure from carbon black. The prepared nanofillers are characterized by X-ray diffraction technique, Fourier transform infrared spectroscopy and transmission electron microscopy. Further, solvent-based epoxy coatings containing 0.1 Wt.% graphene nanosheets and GQDs are prepared, and the corrosion resistance of nanocomposite coatings is considered by electrochemical impedance spectroscopy. Findings The results indicate that both epoxy/graphene nanosheets and epoxy/GQDs samples have significantly higher corrosion resistance than pure epoxy coating. Meanwhile, GQDs can more effectively enhance the corrosion protection performance of epoxy coatings compared to graphene sheets, which can be attributed to the presence of functional groups on GQDs and improving the dispersion quality in polymer matrice. Originality/value In this research, for the first time, the graphene quantum dots (GQDs) prepared by a “top-down” method from carbon black are used as nanofiller in epoxy coatings, and the potential application of graphene nanosheets and GQDs as anti-corrosion nanofiller in epoxy coatings is investigated.

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Wu, Zhong-Shuai, Xinliang Feng, and Hui-Ming Cheng. "Recent advances in graphene-based planar micro-supercapacitors for on-chip energy storage." National Science Review 1, no. 2 (December 6, 2013): 277–92. http://dx.doi.org/10.1093/nsr/nwt003.

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Abstract The current development trend towards miniaturized portable electronic devices has significantly increased the demand for ultrathin, flexible and sustainable on-chip micro-supercapacitors that have enormous potential to complement, or even to replace, micro-batteries and electrolytic capacitors. In this regard, graphene-based micro-supercapacitors with a planar geometry are promising micro-electrochemical energy-storage devices that can take full advantage of planar configuration and unique features of graphene. This review summarizes the latest advances in on-chip graphene-based planar interdigital micro-supercapacitors, from the history of their development, representative graphene-based materials (graphene sheets, graphene quantum dots and graphene hybrids) for their manufacture, typical microfabrication strategies (photolithography techniques, electrochemical methods, laser writing, etc.), electrolyte (aqueous, organic, ionic and gel), to device configuration (symmetric and asymmetric). Finally, the perspectives and possible development directions of future graphene-based micro-supercapacitors are briefly discussed.

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Li, Shixiong, Qiaoling Mo, Xiaoxia Lai, Yufeng Chen, Chuansong Lin, Yan Lu, and Beiling Liao. "Inorganic coordination polymer quantum sheets@graphene oxide composite photocatalysts: Performance and mechanism." Journal of Materials Research 34, no. 18 (July 15, 2019): 3220–30. http://dx.doi.org/10.1557/jmr.2019.207.

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42

Carissan, Yannick, and Wim Klopper. "Growing Graphene Sheets from Reactions with Methyl Radicals: A Quantum Chemical Study." ChemPhysChem 7, no. 8 (August 11, 2006): 1770–78. http://dx.doi.org/10.1002/cphc.200600171.

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43

Glukhova O. E., Slepchenkov M. M., and Kolesnichenko P. A. "Tunneling current between structural elements of thin graphene/nanotube films." Physics of the Solid State 64, no. 14 (2022): 2450. http://dx.doi.org/10.21883/pss.2022.14.54349.180.

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Based on the constructed atomistic models of graphene/nanotube films with different numbers of nanotubes in supercells, we carried out in silico studies of the regularities of the nonuniform density distribution, which determine the presence of an island structure in such films. As a result of quantum molecular dynamics modeling, it is found that thin tubes of subnanometer diameter are enveloped in graphene sheets, which makes them energetically stable and stable. We also studied tunneling contacts between individual film fragments that are not covalently bound, in particular, between graphene sheets with different topologies of contacting zigzag and armchair edges, depending on the distance between them, and between tubes of different chiralities, including (6,3), (4,4), (6,5), (12,6) and (16,0). It is found that the tunnel contacts of tubes with a semiconductor type of conductivity are characterized by the presence of voltage intervals with a negative differential resistance in the I-V characteristic. Such voltage intervals are not observed at all for tubes with a metallic character of conductivity. The new knowledge obtained is important for assessing the electrical conductivity of such films, two-thirds of which are semiconductor tubes. Keywords: graphene, nanotubes, tunnel contacts.

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44

Manoj, B., Ashlin M. Raj, and George Thomas Chirayil. "Facile synthesis of preformed mixed nano-carbon structure from low rank coal." Materials Science-Poland 36, no. 1 (May 18, 2018): 14–20. http://dx.doi.org/10.1515/msp-2018-0026.

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Abstract Coal is a natural energy resource which is mainly used for energy production via combustion. Coal has nanocrystals embedded in it, formed during the coalification process, and is an ideal precursor for nano-carbon dots and diamonds. Herein, we report a facile top-down method to synthesise nanodots and diamonds of the size of 5 nm to 10 nm from three different types of coal by simple chemical leaching. TEM analysis revealed the formation of a mixture of carbon dots, graphene layers, and quantum dots in bituminous coal and sub-bituminous coal. Raman analysis confirmed the existence of synthesized nanodiamond and nano-carbon mixed phase with defects associated with it. It is concluded that graphene quantum dots, nanodiamonds, graphene sheets and carbon dots present in coal can be extracted by simple chemical treatment. These structures can be tuned to photoluminescent material for various optoelectronic applications or energy harvesting devices like super capacitors.

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Sinner, Andreas, and Gregor Tkachov. "Quantum Diffusion in the Lowest Landau Level of Disordered Graphene." Nanomaterials 12, no. 10 (May 14, 2022): 1675. http://dx.doi.org/10.3390/nano12101675.

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Electronic transport in the lowest Landau level of disordered graphene sheets placed in a homogeneous perpendicular magnetic field is a long-standing and cumbersome problem which defies a conclusive solution for several years. Because the modeled system lacks an intrinsic small parameter, the theoretical picture is infested with singularities and anomalies. We propose an analytical approach to the conductivity based on the analysis of the diffusive processes, and we calculate the density of states, the diffusion coefficient and the static conductivity. The obtained results are not only interesting from the purely theoretical point of view but have a practical significance as well, especially for the development of the novel high-precision calibration devices.

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Ying, Yulong, Peng He, Guqiao Ding, and Xinsheng Peng. "Ultrafast adsorption and selective desorption of aqueous aromatic dyes by graphene sheets modified by graphene quantum dots." Nanotechnology 27, no. 24 (May 9, 2016): 245703. http://dx.doi.org/10.1088/0957-4484/27/24/245703.

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47

Riaz, Rabia, Mumtaz Ali, Iftikhar Ali Sahito, Alvira Ayoub Arbab, T. Maiyalagan, Aima Sameen Anjum, Min Jae Ko, and Sung Hoon Jeong. "Self-assembled nitrogen-doped graphene quantum dots (N-GQDs) over graphene sheets for superb electro-photocatalytic activity." Applied Surface Science 480 (June 2019): 1035–46. http://dx.doi.org/10.1016/j.apsusc.2019.02.228.

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48

Глухова, О. Е., М. М. Слепченков, and П. А. Колесниченко. "Туннельный ток между структурными элементами тонких графен/нанотрубных пленок." Физика твердого тела 63, no. 12 (2021): 2198. http://dx.doi.org/10.21883/ftt.2021.12.51684.180.

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Based on the constructed atomistic models of graphene/nanotube films with different numbers of nanotubes in supercells, we carried out in silico studies of the regularities of the nonuniform density distribution, which determine the presence of an island structure in such films. As a result of quantum molecular dynamics modeling, it is found that thin tubes of subnanometer diameter are enveloped in graphene sheets, which makes them energetically stable and stable. We also studied tunneling contacts between individual film fragments that are not covalently bound, in particular, between graphene sheets with different topologies of contacting zigzag and armchair edges, depending on the distance between them, and between tubes of different chiralities, including (6,3), (4,4), (6,5), (12,6) and (16,0). It is found that the tunnel contacts of tubes with a semiconductor type of conductivity are characterized by the presence of voltage intervals with a negative differential resistance in the I – V characteristic. Such voltage intervals are not observed at all for tubes with a metallic character of conductivity. The new knowledge obtained is important for assessing the electrical conductivity of such films, two-thirds of which are semiconductor tubes.

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Das, Ruchira, Priyanka Sow, Sudatta Dey, and Asmita Samadder. "A brief overview on role of graphene based material in therapeutic management of inflammatory response signalling cascades." INTERNATIONAL JOURNAL OF EXPERIMENTAL RESEARCH AND REVIEW 21 (April 30, 2020): 25–36. http://dx.doi.org/10.52756/ijerr.2020.v21.004.

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Graphene is a novel, sp2 carbon atoms bonded, two-dimensional nano-material. Due to their favorable electronic, thermal, optical, and mechanical property, graphene and its derivatives, like graphene oxide (GO) and graphene quantum dots (GQDs) are used in widespread applications. The outstanding potentials of these compounds in the field of nanoelectronics, composite materials, sensors, energy technology etc helped in the rapid development in their functionalization, modulatory effects on various systems of our body. GQDs has been suggested as a new nanomaterial with improved biocompatibility, biodegradability, water solubility and considerably low cytotoxic effects in in vivo models, and are applicable for altering immune responses based on quantum confinement and edge effect properties. The review particularly elucidates the mechanistic approach by which graphene and/ or its derivatives and/ or their nano-compound aid in therapeutic management against myriads of immunological perspectives. GQDs have unique physiochemical properties with carbon sheets showcases out-standing biological response against immunological interventions by altering the activities of t-cell lymphocytes. On the contrary GO plays a vital role in eliciting inflammatory signaling factors by controlling proinflammation and an anti-inflammatory response. Therefore, this review shall help the readers to have an overview of the biomedical application of graphene and its derivatives to design target specific drugs to regulate the immune response based prognosis andcure.

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Riaz, Rabia, Mumtaz Ali, Hassan Anwer, Min Jae Ko, and Sung Hoon Jeong. "Highly porous self-assembly of nitrogen-doped graphene quantum dots over reduced graphene sheets for photo-electrocatalytic electrode." Journal of Colloid and Interface Science 557 (December 2019): 174–84. http://dx.doi.org/10.1016/j.jcis.2019.09.028.

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