Keywords : graphene

From Zero to Infinity: Customized Atomistic Calculations for Crystalline Solids —Applications to Graphene and Diamond

Aristides D. Zdetsis; Shanawer Niaz

Advanced Materials Letters, 2021, Volume 12, Issue 9, Pages 1-1
DOI: 10.5185/amlett.2021.091659

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.

Graphene in Russia: The Main Centers, Research Areas, Results

Grachev Vladimir; Gubin Sergey

Advanced Materials Letters, 2019, Volume 10, Issue 12, Pages 855-859
DOI: 10.5185/amlett.2019.2272

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.

Nano-Graphene and Its Derivatives for Fabrication of Flexible Electronic Devices: A Quick Review

Wee Siang Koh; Kiat Moon Lee; Pey Yi Toh; Swee Pin Yeap

Advanced Materials Letters, 2019, Volume 10, Issue 10, Pages 676-681
DOI: 10.5185/amlett.2019.0050

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.

Magnetic Properties of Intercalated Gr/Ni (111) System

Sergey M. Dunaevsky; Evgeniy K. Mikhailenko; Igor I. Pronin

Advanced Materials Letters, 2019, Volume 10, Issue 9, Pages 633-636
DOI: 10.5185/amlett.2019.0021

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.

Innovative Graphene-PDMS sensors for aerospace applications 

Filomena Piscitelli; Gennaro Rollo; Fabio Scherillo; Marino Lavorgna

Advanced Materials Letters, 2019, Volume 10, Issue 8, Pages 533-538
DOI: 10.5185/amlett.2019.9903

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.

Synthesis of 9-Aminoacridine and its Application as an Anode Material for Aqueous Rechargeable Lithium–ion Batteries

Madhushree M. Ravikumar; Vijeth R. Shetty; Suresh G. Shivappa

Advanced Materials Letters, 2019, Volume 10, Issue 8, Pages 586-594
DOI: 10.5185/amlett.2019.9909

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.

Chemical Reactivity and Electronical Properties of Graphene and Reduced Graphene Oxide on Different Substrates

E. Celasco

Advanced Materials Letters, 2019, Volume 10, Issue 8, Pages 545-549
DOI: 10.5185/amlett.2019.2204

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.

Various surfactants for 0 – 3 dimensional nanocarbons: Separation, exfoliation and solubilization

Naoki Komatsu

Advanced Materials Letters, 2019, Volume 10, Issue 8, Pages 520-523
DOI: 10.5185/amlett.2019.2278

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.

Functionalization of Graphene and Reduced Graphene Oxide in Different Matrices

E. Celasco; M. Sangermano

Advanced Materials Letters, 2019, Volume 10, Issue 7, Pages 460-464
DOI: 10.5185/amlett.2019.2201

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.

Graphene and doped graphene: A comparative DFT study

Jyoti Tyagi; Lekha Sharma; Rita Kakkar

Advanced Materials Letters, 2019, Volume 10, Issue 7, Pages 484-490
DOI: 10.5185/amlett.2019.2168

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.

Increasing the efficiency of graphene-based Schottky-barrier devices

Shuo-En Wu; Ya-Ping Hsieh

Advanced Materials Letters, 2019, Volume 10, Issue 2, Pages 132-135
DOI: 10.5185/amlett.2019.2183

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. 

Removal of dyes from wastewater by nanomaterials : A review

Wenqian Ruan; Jiwei Hu; Jimei Qi; Yu Hou; Chao Zhou; Xionghui Wei

Advanced Materials Letters, 2019, Volume 10, Issue 1, Pages 9-20
DOI: 10.5185/amlett.2019.2148

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. 

Three-dimensional Bi2WO6/graphene aerogel electrode for high-performance supercapacitor

Xun Xu; Fangwang Ming; Jinqing Hong; Zhoucheng Wang

Advanced Materials Letters, 2018, Volume 9, Issue 3, Pages 188-191
DOI: 10.5185/amlett.2018.1719

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.

Graphene-metal oxide nanocomposites for supercapacitors: A perspective review

Vardhaman V. Khedekar; Shaikh Mohammed Zaeem; Santanu Das

Advanced Materials Letters, 2018, Volume 9, Issue 1, Pages 2-19
DOI: 10.5185/amlett.2018.1932

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.

Graphenated ceramic nanofibers for highly sensitive simultaneous detection of dopamine, uric acid and ascorbic acid

Masoud Taleb; Irina Hussainova; Roman Ivanov; Iwona Jasiuk

Advanced Materials Letters, 2017, Volume 8, Issue 12, Pages 1178-1183
DOI: 10.5185/amlett.2017.1557

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. 

Synthesis of WO3@graphene composite for fructose degradation

Zhenya Jiang; Yao Wang; Lifeng Yan

Advanced Materials Letters, 2017, Volume 8, Issue 12, Pages 1184-1187
DOI: 10.5185/amlett.2017.1660

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.

A high energy 3V lithium-ion capacitor synthesized via electrostatic spray deposition

Richa Agrawal; Chunhui Chen; Samantha Dages; Chunlei Wang

Advanced Materials Letters, 2017, Volume 8, Issue 7, Pages 783-790
DOI: 10.5185/amlett.2017.7098

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.

Three-dimensional nanocomposites of graphene/carbon nanotube matrix-embedded Si nanoparticles for superior lithium ion batteries

Dafang He; Lixian Li; Fengjuan Bai; Chenyang Zha; Liming Shen; Harold H. Kung; Ningzhong Bao

Advanced Materials Letters, 2017, Volume 8, Issue 3, Pages 206-211
DOI: 10.5185/amlett.2017.7038

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.

Recent advances in electrochemical biosensor and gas sensors based on graphene and carbon nanotubes (CNT) - A review 

Gounder Thangamani J.; Kalim Deshmukh; Kishor Kumar Sadasivuni; K. Chidambaram; M. Basheer Ahamed; Deepalekshmi Ponnamma; Mariam Al-Ali AlMaadeed; S. K. Khadheer Pasha

Advanced Materials Letters, 2017, Volume 8, Issue 3, Pages 196-205
DOI: 10.5185/amlett.2017.7042

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.

Review of environmental life cycle assessment studies of graphene production

Rickard Arvidsson

Advanced Materials Letters, 2017, Volume 8, Issue 3, Pages 187-195
DOI: 10.5185/amlett.2017.1413

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.

Nitrogen-doped graphene flakes/dots /Fe3N as oxygen reduction reaction electrocatalyst

Rui Yan; Huinian Zhang; Congwei Wang; Yongzhi Liu; Quangui Guo; Junzhong Wang

Advanced Materials Letters, 2017, Volume 8, Issue 3, Pages 223-228
DOI: 10.5185/amlett.2017.1491

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. 

Spin transport in graphene monolayer antiferromagnetic calculated using the Kubo formalism

L. S. Lima

Advanced Materials Letters, 2017, Volume 8, Issue 3, Pages 283-287
DOI: 10.5185/amlett.2017.7045

We have employed the Dirac's massless quasi-particles together with the Kubo's formalism of the linear response to study the spin transport properties by electrons in the graphene monolayer. We have calculated the electric conductivity and verified the behavior of the AC and DC currents of this system, which is a relativistic electron plasma. Our results show a superconductor behavior for the electron transport with the AC conductivity tending to infinity in the limit ω → 0. This superconductor behavior for the electron transport in the graphene is similar to one recently obtained theoretically for the spin transport in the quantum frustrated Heisenberg antiferromagnet in the honeycomb lattice, verifying so a similarity between these two different kinds of transport what can generate futures applications in the modern electronic. 

Supercritical CO2 aided polyindole-graphene nanocomposites for high power density electrode

Harish Mudila; Sweta Rana; Mohammad G. H. Zaidi

Advanced Materials Letters, 2017, Volume 8, Issue 3, Pages 269-275
DOI: 10.5185/amlett.2017.7018

A series of Polyindole/Graphene nanocomposites (PGNCs) as electrochemical energy storage materials were fabricated at varying concentration (%, w/w) of graphene raging 3.0–9.0 in Polyindole (PIN) matrix in Supercritical CO2. The electrochemical behavior of PGNC prepared at different proportion of graphene was investigated. The PGNC@9% has rendered specific capacitance of 389.17 F/g, along with energy and power densities of 13.51 Wh/kg and 511.95 W/kg respectively, which is greater as compared to graphene prepared through thermal reduction of graphene oxide. However, PIN comprises low capacitance of 24.48 F/g. Successive scans of PGNCs electrode for 1000 cycles at the scan rate of 0.1 V/s in KOH (1.0 M) shows a capacitive retention of ~98.6% indicating the electrochemical stability of the electrodes, with successive charge-discharge behavior. PGNCs display all the major peaks in Fourier Transform-Infrared and X-Ray diffraction spectra. Scanning electron micrograph in permutation with XRD spectra indicates the exfoliation of graphene into the matrix of PIN. Simultaneous TG-DSC reveals increased thermal stability of PGNCs with fractions of graphene. The good capacitive and charge-discharge performance indicates that supercritically fabricated PGNCs may serve as potential electrode materials for electrochemical energy storage devices.

The effect of graphene layers on the growth of vanadium oxide nanostructures: Structural, morphological and optical investigations and mechanisms revelation

Issam Derkaoui; Mohammed Khenfouch; Ibrahim Elmokri; Bakang M. Mothudi; Mokhotjwa S. Dhlamini; Sabata J. Moloi. Anouar Jorio; Izeddine Zorkani; Malik Maaza

Advanced Materials Letters, 2017, Volume 8, Issue 3, Pages 276-282
DOI: 10.5185/amlett.2017.1440

Most recently, Vanadium oxide nanoparticles/reduced Graphene oxide (VO-NPs/rGO) nanocomposite have attracted extensive attention due to their potential applications in energy-related areas. Hence, understanding the interactions on behalf the effect of graphene layers on the modification of VO-NPs properties as well as their growth mechanism are of great importance. In this work, our results are revealing that VO-NPs were efficiently grown and coated on the graphene surface and are clearly showing the strong effect of rGO layers on the growth of VO-NPs which leads to a modification in the form, the shape and also the phase. These interactions which were studied based on structural and morphological investigations will play an important role on the modification of these nanocomposites properties which is suitable for a wide range of potential applications and particularly as electrode in Li-ion batteries.

Lamellar structures from graphene nanoparticles produced by anode oxidation

Mykola Kartel; Yuriy Sementsov; Galyna Dovbeshko; Liudmyla Karachevtseva; Stanislav Makhno; Tatiana Aleksyeyeva; Yulia Grebel

Advanced Materials Letters, 2017, Volume 8, Issue 3, Pages 212-216
DOI: 10.5185/amlett.2017.1428

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.

Progress in the graphene research since 2010

Ashutosh Tiwari

Advanced Materials Letters, 2017, Volume 8, Issue 3, Pages 185-186
DOI: 10.5185/amlett.2017.3001

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. 

Two Step Electrochemical Deposition Of Palladium And Polyaniline On Graphene Dispersed Glassy Carbon electrode For Electrochemical Analysis Of Pesticide

M. Sivaprasad; N. Y. Sreedhar; M. R. Jayapal; Li Yang; Hongwei Ni

Advanced Materials Letters, 2017, Volume 8, Issue 1, Pages 30-36
DOI: 10.5185/amlett.2017.6912

Herein we reported graphene (Gr) was firstly fabricated on glassy carbon electrode (GCE) by drop casting method, subsequently  polyaniline (PAN) and Palladium (Pd) nanocomposite were fabricated by two-step electrochemical depositing process on graphene dispersed glassy carbon electrode (Gr/GCE) and used as an electrochemical sensor for determination of Tetrachlorvinphos (TCP < /span>) pesticide in vegetables. Here most of the work has been focused on the preparation and characterization of modified electrode with cyclic voltammetry (CV) and scanning electron microscopy (SEM). The modified composite electrode unveiled significantly good voltammetric response on TCP. Square wave voltammetry (SWV) was used for determination of TCP at optimized conditions such as square wave frequency, step potential, pH of buffer, applied sample volume, accumulation potential and accumulation time. The well-defined reduction (C=C) peaks were acquired over the potential maximum around at -1.3V in acidic medium in Briton-Robinson (B-R) buffer solution at low current values. The low current peaks were obtained over the concentration of TCP at 1.5×10 -6  M with lower detection limit and limit of quantifications are 5.62×10 -10  M and 2.65×10 -8 respectively. The composite modified electrode showed good stability and reproducibility. The proposed method was successfully applied for the present investigation with a great assure as an economical and simple sensor with furthermore a shorter analysis time and further the sensor also used for heavy metal detection in real samples.

An Era Of High-tech Materials

Ashutosh Tiwari

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 1-2
DOI: 10.5185/amlett.2016.1001

The design of innovative materials is one of measure for driving industry to place the sustainable basis of new technology in order to enhance the wealth and well-being of society. The last half century has realized a vital development in the area of high-tech materials ranging from various elements and composites, emerged through synthetic chemistry and often drawing motivation from the nature. The idea of an intelligent material imagines added values in terms of functionality built into the materials structure desirable to response the defined conditions. The previous two decades has emerged to understand the extraordinary behavior and properties of engineered nanostructured materials.

Global Graphene Forum (GGF - 2016), Sweden 

Ashutosh Tiwari

Advanced Materials Letters, 2015, Volume 6, Issue 12, Pages 1025-1025
DOI: 10.5185/amlett.2015.12001

VBRI Press is pleased to announce ‘Global Graphene Forum, during 23 – 25 August 2016, Sweden. It is a three-day international event organised with collaboration of International Association of Advanced Materials (IAAM), and Linkoping University on the Baltic Sea from Stockholm-Helsinki-Stockholm by the Viking Line Cruise, M/S Mariella. The aim of the event is to cover the latest technology developments, applications, commercialization progress, end user requirements and challenges of Graphene and related 2D Materials.

Electronic Structure And NMR Study Of Selected Doped And Functionalized Graphene 

A. Nouri; M. Mirzaei; T. Tayebi; Z. Alipanah

Advanced Materials Letters, 2014, Volume 5, Issue 8, Pages 441-446
DOI: 10.5185/amlett.2014.amwc.1024

In this work, density functional theory (DFT) calculations at the BLYP/6-31G* level was performed to investigate doping and functionalizing effect on the graphene in according geometric, NMR parameters and electronic properties. In the considered models, the energy gap is decreased in doped and functionalized models in respect to the pristine model but there are not significant changes between energy gap of the pristine model and functionalized models. Furthermore, results show the high and low sensitivity of the electronic properties of doped and functionalized models towards pristine model respectively. The results indicate that the formation energies of functionalized models are smaller than doped models ones. The NMR parameters follow the results of structural properties. It was found that for production of electronic devices doped models is better than functionalized models and nitrogen atom is a better choice for this purpose respect to the boron atom. All DFT calculations are performed by the Gaussian 98 package.

Preparation of ZnS-graphene Nanocomposite and its Photocatalytic Behavior for Dye Degradation

B. N. Patil; S. A. Acharya

Advanced Materials Letters, 2014, Volume 5, Issue 3, Pages 113-116
DOI: 10.5185/amlett.2013.fdm.16

In the present work, ZnS-Gaphene (ZnS-GNS) composite was prepared by microwave irradiation method. The prepared samples were characterized by X-ray diffraction (XRD), to confirm the formation of GNS by reducing Graphite as well as ZnS-GNS nanocomposite. Raman spectroscopy identified D and G photon vibration mode of GNS in the ZnS-GNS composite. X-ray photoelectrons spectra are also detected presence of graphene in ZnS. UV/VIS Spectra are studied for evaluation of photocatalytic activity. The composite is explored as photocatalysts to study dye degradation using methylene blue dye in aqueous slurry under irradiation of 663 nm wavelength. Under the same conditions the photocatalytic activity of the pure ZnS is also examined. The ZnS-GNS composite is found in enhancing the rate of photodegradation of toxic dyes as compared to pure ZnS. This Graphene based metal sulphide/oxide semiconductor nanocomposites are high potential material for Photo-degradation of toxic dyes, and act as good photocatalyst.

Thermally Reduced Graphene oxide/thermoplastic Polyurethane Nanocomposites As Photomechanical Actuators 

M. N. Muralidharan;Seema Ansari

Advanced Materials Letters, 2013, Volume 4, Issue 12, Pages 927-932
DOI: 10.5185/amlett.2013.5474

Optically triggered actuators offer unique advantages like wireless actuation and remote control when comared to other type of actuators. They are extremely useful where stimulus other than electricity or heat is preferred. Thermally reduced graphene oxide (TRGO)/thermoplastic polyurethane (TPU) composite actuators were prepared by simple solution casting technique. The photomechanical actuation properties of the composites were studied under infrared illumination. It was found that the photomechanical response can be tuned by controlling the applied prestrain and the filler loading. Even with a low filler loading of 2 wt. % TRGO, the composite exhibited a very high photomechanical strain of 50.2% with an excellent stress of 1680 kPa at a prestrain of 220%. These high values were achieved at a very low light intensity of 16mWcm -2 . The high values of strain obtained with very good generative forces indicate that this is a promising material for light triggered actuators for many potential applications including robotics and biomedical devices.

Surface Affinity Of Graphene For Health, Energy And Environmental Safety Applications

Jyoti Tyagi;Rita Kakkar

Advanced Materials Letters, 2013, Volume 4, Issue 10, Pages 721-736
DOI: 10.5185/amlett.2013.3438

This review focuses on the applications of graphene, and the effects of doping and functionalization on its properties. Though known for several years, the potential applications of graphene in various fields have only been recently realized. Remarkable research is going on in the various application based fields of graphene, such as in hydrogen storage, Li batteries, catalysis and many more. Its use as a sensor to detect various species at the molecular level is fascinating. Also, on account of its 2D structure, graphene has found promising applications in several adsorption phenomena. Various adsorption studies have been done on the graphene surface resulting in the chemisorption of the chemical species. This review focuses on the application of graphene for removal of hazardous substances, such as heavy metal ions and drug metabolites, from waste waters. Another class of substances, known as disinfection by-products (DBPs), formed during the disinfection of drinking water using chlorine, ozone, chloramines and chlorine dioxide as disinfectants, and the use of graphene for their removal, is also discussed. Use of graphene based materials as chemical and biosensors and its applications in various other fields is also briefly discussed.

Spectroscopic And Morphological Analysis Of Graphene Vinylester Nanocomposites

Anupama Chaturvedi; Ashutosh Tiwari; Atul Tiwari

Advanced Materials Letters, 2013, Volume 4, Issue 9, Pages 656-661
DOI: 10.5185/amlett.2013.4469

This communication describes the development of graphene and graphene reinforced polyvinylester nanocomposites. Low concentration of graphene was incorporated in the polymer matrix with the help of two different solvents. The role of solvent in the nanocomposite was studied. The FTIR spectroscopy and electron microscopy have supported the presence of graphene in the nanocomposites. It was discovered that vehicular medium (i.e., solvent) plays a vital role in the properties of the ultimate nanocomposites. When dimethylacetamide was used as solvent, the morphological analysis suggested the increased toughness while in case when tetrahydrofuran was used as solvent, nanocomposite appeared brittle in nature.

Perspectives Of Fluorescent And Cubic Silicon Carbide

Mikael Syv

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 175-176
DOI: 10.5185/amlett.2012.7002

The world of materials science is a fascinating dimension. Findings in materials which were first made many years ago may lead to new frontiers for energy technologies. In these days of increasingly urgent needs for environmental progress, it is a pleasure for a materials scientist to explore materials concepts with potential advances in energy and environmental, or even biomedical, engineering. Already in 1907 it was observed that there could be light emission from an indirect bandgap material namely, carborundum which is an early name of silicon carbide. This observation is referred to as the first report of a light emitting diode. Now more than 100 years after, the silicon carbide is revisited to make a rare earth metal free white LED for general lighting purpose from new insightful perspectives regarding materials synthesis and growth technology implementation.

Fascinating World Of Immerging Graphene Technologies

Atul Tiwari

Advanced Materials Letters, 2012, Volume 3, Issue 2, Pages 172-173
DOI: 10.5185/amlett.2012.2003

After decades, allots of research to exploit the unique properties of graphite resulted to a successful discovery of a new nano material called graphene. Unprecedented efforts by two Manchester University professors resulted in an extraction of a single layer of graphite in the year 2004 that earned them a Nobel Prize of physics in 2010. Several terms that are interrelated to graphene such as graphite nano platelets, graphite oxide, single layer or few layers of graphite oxide, graphene oxide, functionalized graphene sheets or functionalized nano graphene sheets, exfoliated graphene oxide and their numerous processing techniques have appeared in the last few years.