Carbon Materials and Technology
Zacharias Fthenakis; Antonios Fountoulakis; Ioannis Petsalakis; Nektarios Lathiotakis
Abstract
This work is part of a systematic study on the energy barriers for the permeation of several molecules, like He, H2, CO, CO2, H2O, NH3, CH4 etc, through nanoporous single layer graphene, having pores with different shape, size, and type. In the present work, we focus on the permeation of CO2 through ...
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This work is part of a systematic study on the energy barriers for the permeation of several molecules, like He, H2, CO, CO2, H2O, NH3, CH4 etc, through nanoporous single layer graphene, having pores with different shape, size, and type. In the present work, we focus on the permeation of CO2 through graphene pores which are constructed when neighboring carbon atoms of the graphene layer are removed from the structure, and nitrogen atoms have replaced the carbon atoms in the boundary of the pore. The energy barriers for each different pore are calculated using 2 different ReaxFF potentials along a path which the molecule would ideally follow in order to pass from the one side of the membrane to the other through the pore. Using the calculated values of the energy barriers, we estimate permeances by employing the kinetic theory of gasses. We give estimates for the preferable sizes and structures of the pores for permeability and demonstrate the ability of nanoporous graphene for CO2 separation.
Nanomaterials & Nanotechnology
Carsten Strobel; Carlos Chavarin; Sebastian Leszczynski; Karola Richter; Martin Knaut; Johanna Reif; Sandra Voelkel; Matthias Albert; Christian Wenger; Johann Wolfgang Bartha; Thomas Mikolajick
Abstract
A new kind of transistor device with a graphene monolayer embedded between two n-type silicon layers is fabricated and characterized. The device is called graphene-base heterojunction transistor (GBHT). The base-voltage controls the current of the device flowing from the emitter via graphene to the collector. ...
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A new kind of transistor device with a graphene monolayer embedded between two n-type silicon layers is fabricated and characterized. The device is called graphene-base heterojunction transistor (GBHT). The base-voltage controls the current of the device flowing from the emitter via graphene to the collector. The transit time for electrons passing by the ultrathin graphene layer is extremely short which makes the device very promising for high frequency RF-electronics. The output current of the device is saturated and clearly modulated by the base voltage. Further, the silicon collector of the GBHT is replaced by germanium to improve the device performance. This enabled the collector current to be increased by almost three orders of magnitude. Also, the common-emitter current gain (Ic/Ib) increased from 10-3 to approximately 0.3 for the newly designed device. However, the ON-OFF ratio of the improved germanium based GBHT has so far been rather low. Further optimizations are necessary in order to fully exploit the potential of the graphene-base heterojunction transistor.
Computational Materials and Modelling
Aristides D. Zdetsis; Shanawer Niaz
Abstract
We demonstrate that a suitable atomistic method with judicially selected nanoclusters/ nanocrystals (in real space) supplemented with general symmetry and dimensionality arguments, can give surprisingly good results for macroscopic properties of the infinite crystalline solid, such as bandgaps, cohesive ...
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We demonstrate that a suitable atomistic method with judicially selected nanoclusters/ nanocrystals (in real space) supplemented with general symmetry and dimensionality arguments, can give surprisingly good results for macroscopic properties of the infinite crystalline solid, such as bandgaps, cohesive energies, as well as aromaticity (if any), at minimal computational cost and maximum physical insight. For graphene on top of these properties the present approach can successfully describe in real space and illuminate many of its exotic properties, which are usually introduced in k-space, such as Dirac points or topological insulators. An early version of this methodology has been very successfully applied and extrapolated to Si, Be, BeH, CdSe, MgH, crystals and nanocrystals, with almost chemical accuracy in most cases. Here, after a pedagogical and critical review of the earlier results, we introduce a new combined and expanded approach to comparatively describe the electronic and cohesive properties of diamond and graphene. For the later a drastically enlarged sequence of “nanocrystals” of well-chosen geometries and sizes up to 1440 atoms or 8190 electrons is used to verify earlier predictions and results. We have obtained in a simple and fast way the bandgap (5.4 eV) and the cohesive energy (7.34 eV/atom) of diamond with almost chemical accuracy; and we have fully rationalized (in a different perspective and prospective) the electronic and cohesive properties of graphene, with a tentative value of cohesive energy of 7.52 eV/atom. Strangely enough this value is larger than the one for diamond and is currently under investigation. Finally, we suggest that this methodology in its current simple and transparent form can be a first-line diagnostic, functional, and inexpensive computational tool. This is particularly true for quick assessments and comparative estimates, size-dependence studies, or cases where standard k-space methods or other advanced techniques either fail or demand unavailable computational resources.
Grachev Vladimir; Gubin Sergey
Abstract
Russian graphene research centers are presented, in which the most significant results were obtained. The cities, scientific groups, their leaders, main research areas are listed: methods of synthesis and diagnostics of graphene and graphene-like structures, theoretical methods in the application to ...
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Russian graphene research centers are presented, in which the most significant results were obtained. The cities, scientific groups, their leaders, main research areas are listed: methods of synthesis and diagnostics of graphene and graphene-like structures, theoretical methods in the application to graphene materials, devices based on graphene and related structures - sensors of physical characteristics, fuel cells, biosensors etc., the application of graphene and related 2D materials in electronics, photonics, spintronics, optoelectronics, bioelectronics. The large-scale production of graphene and graphene-like structures is also covered. The main sources of publications of Russian researches and their colleagues are also listed. Copyright © VBRI Press.
Wee Siang Koh; Kiat Moon Lee; Pey Yi Toh; Swee Pin Yeap
Abstract
Along with technology development, the demand for flexible, foldable, and portable electronic devices has grew over the past few years. Successful fabrication of this flexible electronic devices relying on the internal electronic components which are also flexible and lightweight. In this regard, researchers ...
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Along with technology development, the demand for flexible, foldable, and portable electronic devices has grew over the past few years. Successful fabrication of this flexible electronic devices relying on the internal electronic components which are also flexible and lightweight. In this regard, researchers are now working on using nanomaterials which exhibit the desired electronic properties to replace the conventional electronic components. Graphene nanosheet and its derivatives are known for their intrinsic electrical behaviour. Meanwhile, they are lightweight and consume small space in any design. Hence, recent research has been focussing on fabricating flexible and foldable electronic components by attaching the graphene and its derivatives on a thin film/substrate. In fact, this idea has been realized in year 2017 on the first flexible OLED panel that uses transparent graphene-based electrode. In view of the positive impact of this nanomaterial towards future design of electronic devices, the present paper aims to provide a quick review on the current stage of research, the challenges encountered, as well as the future outlook in the use of graphene nanomaterials for designing flexible electronics. Copyright © VBRI Press.
Sergey M. Dunaevsky; Evgeniy K. Mikhailenko; Igor I. Pronin
Abstract
Intercalation of graphene (Gr) with transition metals is perspective for creating magnetic tunnel junctions and structures of the type graphene/ferromagnetic metal/substrate with perpendicular magnetic anisotropy (PMA). The paper presents the results of first-principle calculations of the magnetic properties ...
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Intercalation of graphene (Gr) with transition metals is perspective for creating magnetic tunnel junctions and structures of the type graphene/ferromagnetic metal/substrate with perpendicular magnetic anisotropy (PMA). The paper presents the results of first-principle calculations of the magnetic properties for Gr/Fe (Co)/Ni (111) systems. Ab initio calculations of the electron spectrum of the systems were performed in the framework of the spin density functional theory (SDFT). Kohn-Sham single-particle spectra were used to determine total energies of the systems for different spin quantization axes, partial and total densities of the electron states, and also magnetic moments of all atoms. Then, using these magnetic moments, the energies of dipole-dipole interaction were obtained and the magnetic crystalline anisotropy (MCA) of the systems was studied. Copyright © VBRI Press.
Naoki Komatsu
Abstract
Nanocarbons are carbon allotropes with nanometer scale and comprised mainly of 0 – 3 dimensional (0D – 3D) forms; fullerenes (0D), carbon nanotubes (1D), graphene (2D), and nanodiamond (3D). In our group, various surfactants with appropriate size and shape have been developed for the nanocarbons. ...
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Nanocarbons are carbon allotropes with nanometer scale and comprised mainly of 0 – 3 dimensional (0D – 3D) forms; fullerenes (0D), carbon nanotubes (1D), graphene (2D), and nanodiamond (3D). In our group, various surfactants with appropriate size and shape have been developed for the nanocarbons. In order to separate the fullerenes, bowl-shaped surfactants were designed and synthesized to accommodate the 0D spherical nanocarbon, giving C70 selectively as precipitates. On the other hand, gable- and bracket-shaped surfactants formed stable complexes with 1D tubular nanocarbons, dispersing carbon nanotubes with specific diameter, handedness and/or metallicity selectively in solution phase. The flat surfactants worked as an exfoliant and dispersant for graphite in both wet and dry processes; sonication and ball milling, respectively. They gave graphene composites with high concentrations and yield in aqueous solution and low-boiling point organic solvents. The hyper-branched polymer named polyglycerol coated the nanodiamond surface covalently through ring-opening polymerization of glycidol. The chemisorped polymer gave large hydrophilicity to the nanodiamond, dispersing it stably in aqueous solutions such as water and phosphate buffer as well as polar organic solvents such as methanol. Copyright © VBRI Press.
Filomena Piscitelli; Gennaro Rollo; Fabio Scherillo; Marino Lavorgna
Abstract
For aerospace morphing and deployable applications, the use of PDMS-based sensors is crucial because they are characterized by easy application on large surfaces, light design, very large deformations, and durability in harsh environmental conditions. In this contest, the goal of the present work is ...
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For aerospace morphing and deployable applications, the use of PDMS-based sensors is crucial because they are characterized by easy application on large surfaces, light design, very large deformations, and durability in harsh environmental conditions. In this contest, the goal of the present work is to manufacture innovative, highly deformable, piezoresistive sensors, manufactured by using a simplified and scalable method for the applications on large-area, such as the airplane wings. To this end, an ad-hoc polymeric matrix was designed by crosslinking Polydimethylsiloxane (PDMS) oligomers OH terminated with siloxane domains, obtained from hydrolysis and condensation of tetraethyl orthosilicate (TEOS). In particular, the solution of siloxanes domains precursors contributes to lower the viscosity without any solvents and to create, after curing, a fine crosslinked system which could withstand high deformation. Nanocomposites with graphene (6 - 15 wt%) were prepared by dispersing the filler into the polymeric precursor by adopting both magnetic stirring and sonication. Regardless the dispersion method and the filler concentration, few-layers of graphene coexists with large aggregations, and the electrical conductivity and the Gauge Factor increase as the graphene content increases. It was found that the graphene filler tends to hinder the evaporation of solvents developed during the crosslinking reactions, generating porosity and enhancing conductivity. A better filler dispersion obtained through sonication reduces the conductivity. All nanocomposites show a good linear relationship between the strain and the relative electrical resistance change, since the non-linearity remains below the 5%, and quite no-drift can be observed in a wide operative range. Copyright © VBRI Press.
E. Celasco
Abstract
The chemical reactivity and the electronical properties variation of graphene (G) supported on Ni(111) and of the reduced Graphene Oxide (rGO) will be described thanks to the framework of University of Genoa and Polytechnic of Turin. We will present the main results obtained on the reactivity, towards ...
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The chemical reactivity and the electronical properties variation of graphene (G) supported on Ni(111) and of the reduced Graphene Oxide (rGO) will be described thanks to the framework of University of Genoa and Polytechnic of Turin. We will present the main results obtained on the reactivity, towards CO, of pristine graphene grown on Ni(111). Single layer graphene films are grown by ethene dehydrogenation on Nickel, under different experimental conditions, and the system is studied in-situ by X-ray Photoemission and High-Resolution Electron Energy Loss Spectroscopies before and after CO exposure at 87 K and at room temperature. The main results were: the best CO reactivity in the top-fcc configuration of graphene on Ni(111), at low temperature. the higher reactivity occurs in the case of minimum percentage of contaminant or Ni2C still present during the grown process. a reactivity toward CO at room temperature on graphene with punctual controlled defects by sputtering, with possible applications e.g., gas sensing. More applicative aspect is the modification of GO in rGO, by UV based process. During the reduction, electrical properties is improved, opening possible application in the ink-jet printing mechanism as conductive printing system, coating or in the functionalization of G. Copyright © VBRI Press.
Madhushree M. Ravikumar; Vijeth R. Shetty; Suresh G. Shivappa
Abstract
Two organic compounds namely Acridine (ACD) and 9-aminoacridine (ACD-NH2) have been investigated as electrode materials for an aqueous rechargeable lithium-ion battery (ARLIB) applications. The electrochemical investigations reveal that the active species act as anodes in ARLIB systems. In this regard, ...
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Two organic compounds namely Acridine (ACD) and 9-aminoacridine (ACD-NH2) have been investigated as electrode materials for an aqueous rechargeable lithium-ion battery (ARLIB) applications. The electrochemical investigations reveal that the active species act as anodes in ARLIB systems. In this regard, nitrogen group act as redox center and undergo electrochemical reaction with Li-ions during charge and discharge process. The synthesis of 9-amonoacridine is done by standard method called chichibabin reaction. Amination of ACD enhances the electrochemical behaviour of the molecule. To improve the electrochemical performances of ACD & ACD-NH2, graphene is used as an additive for ARLIB system. The decorated molecules such as decorated Acridine (dACD) and decorated 9-aminoacridine (dACD-NH2) showed improved electrochemical performance as compared with ACD & ACD-NH2. The decoration is of great importance concerning capacity, reversibility and stability of cycling behavior during charge and discharge processes. Charge/discharge tests show that ACD, ACD-NH2, dACD, and dACD-NH2 have achieved initial discharge capacities of 119, 122, 149 and 220 mAh g -1 respectively at a current density of 0.2 mA. The good cyclic performance and agreeable discharge capacity of the cell signifies the application of dACD-NH2 as anode material for ARLIB system. Copyright © VBRI Press.
E. Celasco; M. Sangermano
Abstract
Graphene (G) presents a huge variety of intriguing properties, as extraordinary electronic transport characteristics. G, thanks to its low chemical reactivity, can also be used as an active support for catalytic nanoparticles. Some possible graphene application could be: its employment in active material ...
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Graphene (G) presents a huge variety of intriguing properties, as extraordinary electronic transport characteristics. G, thanks to its low chemical reactivity, can also be used as an active support for catalytic nanoparticles. Some possible graphene application could be: its employment in active material in electronic devices such as sensors, batteries, supercapacitors, hydrogen storage systems or as fillers to produce multifunctional nanocomposite polymeric materials. In more detail we would like to examine: different approach of reduction and functionalization of in situ reduced graphene oxide obtaining an enhancement of thermal conductivity and an resistivity decrease. Surface modification and functionalization of rGO to improve its dispersion in organic solvent and also polymeric matrix. Copyright © VBRI Press.
Jyoti Tyagi; Lekha Sharma; Rita Kakkar
Abstract
Two different models, ovalene (C32H14) and circumcoronene (C54H18) and their respective doped models (C31XH14, C53XH18 where X = B, Al, N, P, Fe, Ni and Pt) have been considered for DFT calculations at the GGA-PBE/DNP level. The two models are compared on the basis of various calculated structural parameters ...
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Two different models, ovalene (C32H14) and circumcoronene (C54H18) and their respective doped models (C31XH14, C53XH18 where X = B, Al, N, P, Fe, Ni and Pt) have been considered for DFT calculations at the GGA-PBE/DNP level. The two models are compared on the basis of various calculated structural parameters and electronic properties. Electronic density of states (DOS) spectra are also plotted to see the changes in the electronic properties on increasing the size. No major changes are observed in the structural and electronic properties as one move from the smaller model to the higher one. It is found that doping maintains the planarity of the surface but induces comparatively large changes in the bond lengths around the doped atom, weakening the bonds. Copyright © VBRI Press.
Shuo-En Wu; Ya-Ping Hsieh
Abstract
Graphene’s high carrier mobility and ambipolar nature has the potential to improve electronic devices. The absence of a band-gap necessitates heterostructure devices. Schottky-barrier devices consisting of an interface between graphene and a semiconductor represent the simplest heterostructure. ...
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Graphene’s high carrier mobility and ambipolar nature has the potential to improve electronic devices. The absence of a band-gap necessitates heterostructure devices. Schottky-barrier devices consisting of an interface between graphene and a semiconductor represent the simplest heterostructure. Despite its simplicity, graphene-based Schottky barrier devices are not well understood and exhibit low injection efficiencies. We here investigate the impact of graphene/metal interaction on the properties of the Schottky-barrier. Besides the commonly employed Au/graphene we use Pt/graphene contacts. We find that the injection efficiency for Pt is 5x higher than for Au and systematically study the origin of this behavior. We identify a large difference in Richardson’s constant due to changes in the density of surface states. The demonstrated ability to increase the injection current was applied to improve the efficiency of graphene-based Schottky solar cells by 13x.
Wenqian Ruan; Jiwei Hu; Jimei Qi; Yu Hou; Chao Zhou; Xionghui Wei
Abstract
Dyes are widely used to colour products in textile, leather tanning, cosmetics, pigment and many other industries. Effluents discharged from these industries cause potential hazards to environment and human health. Hence, the removal of dyes from water/wastewater has gained a huge attention in recent ...
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Dyes are widely used to colour products in textile, leather tanning, cosmetics, pigment and many other industries. Effluents discharged from these industries cause potential hazards to environment and human health. Hence, the removal of dyes from water/wastewater has gained a huge attention in recent years. So far, biological, chemical and physical methods are the traditional techniques, of which adsorption is found to be a more effective and cheap method for removing dyes. Nanotechnology has applied successfully to the water/wastewater treatment and emerged as a fast-developing promising field. Application of nanomaterials (NMs) in dyes removal seems to be an efficient way. In this review, extensive literature information was presented with regard to dyes, its classification and toxicity, different methods for dyes removal including the removal of dyes by NMs. It is evident from the literature survey that NMs have shown good capability for the removal of dyes.
Xun Xu; Fangwang Ming; Jinqing Hong; Zhoucheng Wang
Abstract
Graphene-based aerogels with porous structure and three-dimensional (3D) network have attracted plentiful interests recently because they could exhibit as an excellent matrix for various kinds of nanoparticles, thus providing a potential prospect in a variety of applications. In this report, 3D composite ...
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Graphene-based aerogels with porous structure and three-dimensional (3D) network have attracted plentiful interests recently because they could exhibit as an excellent matrix for various kinds of nanoparticles, thus providing a potential prospect in a variety of applications. In this report, 3D composite aerogel with poriferous structure assembly of bismuth tungstate sheets and graphene nanosheets has been prepared by a simple hydrothermal process. The 3D multihole structure of the hybrid aerogel could not only provide enormous surface area, but also facilitate electron transfer and ion transmission which could decrease the electrode internal resistance and consequently improve the capacitive property. As a result, the Bi2WO6/graphene hybrid aerogel achieves a large specific capacitance of 714 F g -1 at the current density of 4 A g -1 . The hybrid aerogel could provide a new method for developing high-performance energy storage materials.
Vardhaman V. Khedekar; Shaikh Mohammed Zaeem; Santanu Das
Abstract
Graphene-Metal oxide nanocomposites have been extensively investigated due to their potential applications in the fields of energy devices, including, solar cells, fuel cells, batteries, sensors, electro-catalysis, and photo-catalysis. Among them, several researches have been performed on supercapacitors, ...
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Graphene-Metal oxide nanocomposites have been extensively investigated due to their potential applications in the fields of energy devices, including, solar cells, fuel cells, batteries, sensors, electro-catalysis, and photo-catalysis. Among them, several researches have been performed on supercapacitors, which could be best used with devices that require high current for short duration of time. Here, in this article, we present a brief review on the recent advances on the graphene-metal oxide nanocomposites for supercapacitor technologies and the future perspective of this field of research. A wide range of graphene-metal oxide synthesis techniques have been discussed with a focus on the advancement of nanocomposites with controlled features, including, particle size, morphologies, surface structures, pore size, pore-distributions, etc. Specifically, various nanocomposites and their role in supercapacitor electrodes are discussed with their explicit electrochemical charge-storage mechanisms along with charge-transfer techniques. Furthermore, this analysis demonstrates current trends and future directions in research on graphene-metal oxide nanocomposite electrodes for the performance enhancement in next-generation supercapacitor devices.
Masoud Taleb; Irina Hussainova; Roman Ivanov; Iwona Jasiuk
Abstract
The present study reports the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) in 0.1 M phosphate buffer solution (pH = 7.0) using a novel electrode material prepared from oxide ceramic nanofibers by applying a single step chemical vapor deposition method. Electron-transfer ...
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The present study reports the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) in 0.1 M phosphate buffer solution (pH = 7.0) using a novel electrode material prepared from oxide ceramic nanofibers by applying a single step chemical vapor deposition method. Electron-transfer kinetics at the electrode/solution interface was studied by standard redox reaction of 5 mM Fe(CN)6 3-/4- in 1 M KCl. Electrochemical and sensing measurements such as cyclic voltammetry and differential pulse voltammetry were performed to detect DA and UA in the presence of AA. The developed electrode was shown to separate the overlapping voltammetric responses of three analytes into the individual voltammetric peaks, totally eliminate the interference from AA, and distinguish DA from UA. Linear relationship was observed between current intensities and concentrations of all three compounds, and the limits of detection (LOD) were reached 0.57 µM, 0.77 µM and 0.84 µM for DA, UA and AA, respectively. The electrode of graphenated nanofibers displayed a very good reproducibility and stability, and was successfully tested for detection of DA, UA and AA in real urine samples.
Zhenya Jiang; Yao Wang; Lifeng Yan
Abstract
WO3@Graphene (WO3@GR) nanocomposite has been synthesized by using a simple sonochemical method, and the phosphotungstic acid was used as the source of the WO3 nanoparticles. The new catalyst was analyzed by means of FT-IR, XRD, TEM, and SEM-EDX. FT-IR spectrum of the new material reveals that sulfonic ...
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WO3@Graphene (WO3@GR) nanocomposite has been synthesized by using a simple sonochemical method, and the phosphotungstic acid was used as the source of the WO3 nanoparticles. The new catalyst was analyzed by means of FT-IR, XRD, TEM, and SEM-EDX. FT-IR spectrum of the new material reveals that sulfonic acid groups existed on the surface of graphene nanosheets. In addition, TEM image of WO3@GR indicates that the WO3 nano-particles in size of 5-10 nm have an uniform distribution on the surface of the graphene nanosheets. The as-prepared nanocomposite can be used as a catalyst for biomass conversion, and the catalytic hydrolysis of fructose was carried out at different experiment conditions, such as reaction temperature, reaction time and catalyst dosage. HPLC has been used to measure the compounds in product and their yield. It was found that the major products include HMF, formic acid, lactic acid, acetic acid, and maleic acid, and the maximum yield is 43.25% when the reaction was carried out at 160 o C with the ratio of fructose to catalyst is 8 in the presence of 20 ml of water for 2h. The results reveal that the WO3@GR nanocomposite is a potential catalyst for biomass conversion.
Richa Agrawal; Chunhui Chen; Samantha Dages; Chunlei Wang
Abstract
Reduced graphene oxide-carbon nanotube (rGO-CNT) and anatase TiO2-Li4Ti5O12 (ATO-LTO) composite electrodes were synthesized via electrostatic spray deposition (ESD) and analyzed as cathode and anode vs. lithium, respectively. The rGO-CNT and ATO-LTO electrodes were able to deliver discharge ...
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Reduced graphene oxide-carbon nanotube (rGO-CNT) and anatase TiO2-Li4Ti5O12 (ATO-LTO) composite electrodes were synthesized via electrostatic spray deposition (ESD) and analyzed as cathode and anode vs. lithium, respectively. The rGO-CNT and ATO-LTO electrodes were able to deliver discharge capacities of ca. 63 mAhg -1 and 95 mAhg -1 , respectively for a current rate of 0.1 Ag -1 with superior rate capability and cycle stability. Post electrode analyses, lithium-ion hybrid electrochemical capacitors (Li-HEC) were constructed comprising a prelithiated ATO-LTO anode and an activated rGO-CNT cathode in a carbonate based 1M LiPF6 salt electrolyte. The Li-HEC cells were stable for a cell potential of 0.05-3V and were able to deliver a maximum gravimetric energy density of 33.35 Whkg -1 and a maximum power density of 1207.4 Wkg -1 , where the cell parameters were normalized with the total mass of the anode and cathode active materials. Furthermore the Li-HEC cells were able to retain ~77% of the initial capacity after 100 cycles. The superior Li-HEC performance is attributed to the utilization of a prelithiated lithium-intercalating anode and a double layer cathode in an asymmetric configuration. The feasibility of using a low-cost, facile process like ESD was therefore shown to produce high performance Li-HECs.
Ashutosh Tiwari
Abstract
With exotic discovery of graphene, the focus of researchers brings initiatives in field of atom-thick two-dimensional (2D) materials having exceptional and extraordinary properties. In year 2010, Prof. Andre Geim and Prof. Konstantin Novoselov from the University of Manchester, UK were jointly awarded ...
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With exotic discovery of graphene, the focus of researchers brings initiatives in field of atom-thick two-dimensional (2D) materials having exceptional and extraordinary properties. In year 2010, Prof. Andre Geim and Prof. Konstantin Novoselov from the University of Manchester, UK were jointly awarded the Nobel Prize in Physics for their ground-breaking experiments on the two-dimensional material graphene. Data elucidated from Scopus indicates that since 2010, on graphene 77, 221 documents have been published from over 120 countries. Number of documents reported on graphene increased from 3,748 to 16,378 since 2010 to 2016.
Rickard Arvidsson
Abstract
Environmentally benign production processes are required in order to ensure a sustainable graphene supply. Life cycle assessment (LCA) is an established method for assessing life cycle environmental impacts of products and production processes. In this paper, life cycle impacts of five production processes ...
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Environmentally benign production processes are required in order to ensure a sustainable graphene supply. Life cycle assessment (LCA) is an established method for assessing life cycle environmental impacts of products and production processes. In this paper, life cycle impacts of five production processes for graphene are reviewed: Chemical reduction of graphite oxide, ultrasonication exfoliation, thermal exfoliation, chemical vapour deposition, and epitaxial growth. The reduction step, including the production of the reduction agent hydrazine, was the main contributor for most impacts in the chemical reduction of graphite oxide. Production of the solvent diethyl ether was the step that contributed the most for ultrasonication exfoliation, so solvent recovery is advised. For thermal exfoliation, microwave heating was the step that contributed the most to environmental impacts of graphene nanoplatelets. For chemical vapour deposition, the methane feedstock production step contributed the most, but methane recovery could reduce the energy use considerably. The environmental impacts of epitaxial graphene were dominated by electricity use for production of the silicon wafer substrate, which means that a ‘greener’ electricity mix can reduce impacts considerably. Overall, it is shown that graphene need not be an energy-intensive material compared to conventional materials used in society today.
Gounder Thangamani J.; Kalim Deshmukh; Kishor Kumar Sadasivuni; K. Chidambaram; M. Basheer Ahamed; Deepalekshmi Ponnamma; Mariam Al-Ali AlMaadeed; S. K. Khadheer Pasha
Abstract
Graphene and carbon nanotubes (CNTs) based sensors have been extensively studied because of their applications in the detection of various chemicals and biomolecules. From an application point of view, high sensitivity and selectivity is a promising tool for fast detection of gas leakage and early diagnosis ...
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Graphene and carbon nanotubes (CNTs) based sensors have been extensively studied because of their applications in the detection of various chemicals and biomolecules. From an application point of view, high sensitivity and selectivity is a promising tool for fast detection of gas leakage and early diagnosis of diseases for health care. In the present review article, we provide a comprehensive overview on the recent advances in the development of graphene and CNT based electrochemical biosensors and gas sensors. From the future point of view, special attention is paid to the synthesis techniques for high-performance biosensors and gas sensors. This article focuses on detecting mechanism for various volatile organic compounds (VOCs) gas sensing behavior of the graphene and CNT based sensors. A comparative study of the sensing behavior of pure metal oxide nanoparticles as well as their hybrids with graphene and CNTs has been reported.
Dafang He; Lixian Li; Fengjuan Bai; Chenyang Zha; Liming Shen; Harold H. Kung; Ningzhong Bao
Abstract
A unique hierarchically nanostructured composite of Si nanoparticles (Si NPs) embedded in a three-dimensional (3D) carbon nanotube (CNT)/graphene sheet (GS) matrix (Si@CNT/GS) is fabricated by freeze-drying and thermal reduction. In this novel nanostructured composite, since the intertwined elastic CNTs ...
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A unique hierarchically nanostructured composite of Si nanoparticles (Si NPs) embedded in a three-dimensional (3D) carbon nanotube (CNT)/graphene sheet (GS) matrix (Si@CNT/GS) is fabricated by freeze-drying and thermal reduction. In this novel nanostructured composite, since the intertwined elastic CNTs effectively disperse the Si NP anode material and provide extra physical connections between Si NPs and the surrounding 3D conductive matrix, the interconnected 3D CNT/GS matrix can serve to buffer the volume change of the Si NPs during cycling while simultaneously enhance the electrical conductivity of the overall electrode. As a result, Si@CNT/GS nanocomposite exhibits a high reversible capacity of 1362 mAh·g -1 at 500 mA·g -1 over 500 cycles, and an excellent rate capability of 504 mAh·g -1 at 8400 mA·g -1 , considerably improving the battery performance compared with those electrodes made from Si@graphene nanocomposites, thus exhibiting great potential as an anode composite structure for lithium storage. Copyright © 2017 VBRI Press.
Mykola Kartel; Yuriy Sementsov; Galyna Dovbeshko; Liudmyla Karachevtseva; Stanislav Makhno; Tatiana Aleksyeyeva; Yulia Grebel
Abstract
An effective cheap method for graphene nanoparticles (GNP) production with controlled size distribution was developed based on anodic oxidation of condensed exfoliated graphite. As it is shown, under certain condition the GNP could be self-organized into a 3-dimensional structure that could be important ...
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An effective cheap method for graphene nanoparticles (GNP) production with controlled size distribution was developed based on anodic oxidation of condensed exfoliated graphite. As it is shown, under certain condition the GNP could be self-organized into a 3-dimensional structure that could be important for understanding of the GNP interaction with different type of surfaces. Based on this feature, a synthesis method for preparation of composites containing GNP and polychlorotrifluoroethylene (PCTFE) was developed. Raman spectroscopy of GNP and GNP/PCTFE revealed a good crystalline structure of synthesized nanoparticles. Laser correlation spectroscopy and electron microscopy studies show that average size of particles ranges from tens to thousands nanometers and thickness consists ten or more graphene layers. We found that conductivity of GNP is of electronic nature. The real and imaginary parts of complex permittivity in the microwave range and electric conductivity at low frequencies were found to be a nonlinear function of a volume content of GNP in GNP/PCTFE composite. It could be explained by a presence of the percolation threshold equals to 0.5 wt.%. Low percolation threshold of GNP/PCTFE composite as self-organized 3D structure, could be a certificate of high surface energy for the particles strongly interacting with the surrounding media.
Rui Yan; Huinian Zhang; Congwei Wang; Yongzhi Liu; Quangui Guo; Junzhong Wang
Abstract
Nitrogen-doped graphene flakes/dots/Fe3N hybrids were synthesized by electrochemical charging/discharging of graphite in ionic liquid/water followed by thermal annealing at the presence of FeCl3. Rich edges of graphene dots and porous graphene flakes from electrochemical etching probably supply heteroatom-doping ...
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Nitrogen-doped graphene flakes/dots/Fe3N hybrids were synthesized by electrochemical charging/discharging of graphite in ionic liquid/water followed by thermal annealing at the presence of FeCl3. Rich edges of graphene dots and porous graphene flakes from electrochemical etching probably supply heteroatom-doping sites and active catalytic sites while porous graphene flakes support good electrical conductivity and pathway for electrons/ions/gases. The graphene flakes/dots/Fe3N material obtained at 700 °C shows the highest oxygen reduction reaction (ORR) activity with half-wave potential of 753 mV (vs RHE) and better durability and tolerance of methanol than Pt/C.
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