Search for: graphene
Total 811 records
Recent developments in graphene and graphene oxide: properties, synthesis, and modifications: a review, Article ChemistrySelect ; Volume 5, Issue 33 , 2020 , Pages 10200-10219 ; Abbaspour, S ; Abdolahi Sadatlu, M. A ; Mirkiani, S ; Ghasemi, A ; Hoseini Ghahfarokhi, M ; Mozaffari, N ; Karimi, M ; Hamblin, M. R ; Sharif University of Technology
Graphene was first discovered as a sheet structure mechanically exfoliated from a block of graphite, but in recent years researchers have extended their investigations into this two-dimensional carbon nanostructure. Various applications of graphene-based materials have included electronics, photonics, optoelectronics, sensors, and drug / gene delivery systems. These single atom carbon layers have the potential to be formed in different morphologies e. g., quantum dots, nanosheets, and nanoparticles, which can be tailored to achieve new breakthrough innovations. Nowadays, the utilization of graphene-based nanomaterials in medicine is a hot research topic. This review discusses the structure,...
Compact formulae for number of conduction channels in various types of graphene nanoribbons at various temperatures, Article Modern Physics Letters B ; Volume 26, Issue 1 , 2012 ; 02179849 (ISSN) ; Faez, R ; Moravvej Farshi, M. K ; Sharif University of Technology
We present two compact analytic formulae for calculating the channel number in graphene nanoribbons (GNRs), in terms of GNRs' width and Fermi energy. Numerical data obtained from these analytic formulae fit those obtained numerically from the exact formula, with accuracies within 1%. Using appropriate fit parameters, the compact formulae are valid for zigzag, armchair-metallic, and armchair-semiconducting GNRs, at room, liquid nitrogen, and liquid helium temperatures (i.e. 300, 77 and 4.2 K)
Electronic properties of hydrogenated quasi-free-standing graphene, Article Physica Status Solidi (B) Basic Research ; Volume 248, Issue 11 , OCT , 2011 , Pages 2639-2643 ; 03701972 (ISSN) ; Petaccia, L ; Wang, Y ; Quian, H ; Farjam, M ; Jafari, S. A ; Sachdev, H ; Federov, A. V ; Usachov, D ; Vyalikh, D. V ; Liu, X ; Vilkov, O ; Adamchuk, V. K ; Irle, S ; Knupfer, M ; Büchner, B ; Grüneis, A ; Sharif University of Technology
Tailoring the electronic properties of graphene is of fundamental interest regarding its application in electronic devices. One of the key strategies is chemical functionalization which modifies the p-electron system and thus can induce band gaps. However, in order to control the degree of functionalization it is crucial to know the exact amount of the chemisorbed species. We show with angle-resolved photoemission spectroscopy (ARPES) the formation of a band gap in graphene and estimate the hydrogen coverage from the scattering rate. Using X-ray photoemission spectroscopy (XPS) we identify the chemical environments in hydrogenated graphene and determine the total hydrogen to carbon...
Preparation and characterization of self-electrical stimuli conductive gellan based nano scaffold for nerve regeneration containing chopped short spun nanofibers of PVDF/MCM41 and polyaniline/graphene nanoparticles: Physical, mechanical and morphological studies, Article International Journal of Biological Macromolecules ; 2020 ; Ramazani S., A ; H Shirazi, F ; Hassanzadeh Nemati, N ; Sharif University of Technology
Elsevier B.V 2020
Conductive self -electrical stimuli bioactive scaffolds could be used the potential for peripheral nerve regeneration with the maximum efficiency. To produce such conductive self-electrical stimuli bioactive scaffolds, chopped spun piezoelectric nanofibers of polyvinylidene fluoride/mesoporous silica nanoparticle (PVDF/MCM41) are prepared and incorporated in gellan/polyaniline/graphene (gellan/PAG) nanocomposites which have been previously prepared by incorporation of polyaniline/graphene (PAG) nanoparticles in gellan gel at 80 °C. Highly conductive binary doped polyaniline/graphene nanoparticles are prepared by chemical oxidative polymerization of aniline monomer using in-suite...
Synthesis and Functionalization of Graphene for Uranium Adsorption, M.Sc. Thesis Sharif University of Technology ; Outokesh, Mohammad ; Khanchi, Alireza
Many concerns are directed toward heavy metal pollutions due to its environmental hazards, and many researchers have been working on elimination of heavy metals recently. The large volume of industrial wastewater and the probability of potable water resources pollutions, clarifies the importance of heavy metals removal from wastewater. Removing Uranium among all other heavy metals is of a great importance because of its radioactive and chemical toxication. This thesis topic is “Synthesis and Functionalization of Grapheme for Uranium Adsorption”. In order that, Graphene Oxide is fabricated from Graphite utilizing Hummers and Offman’s method firstly, and it is functionalized by two ligands...
Albumin-graphene oxide conjugates; Carriers for anticancer drugs, Article RSC Advances ; Vol. 4, issue. 62 , July , 2014 , pp. 33001-33006 ; ISSN: 20462069 ; Pourjavadi, A ; Adeli, M ; Sharif University of Technology
In order to improve its biological properties, graphene oxide can be modified with hydrophilic polymers. Therefore, in this study, the surface of graphene oxide was modified with polyethylene glycol and albumin by covalent methods. In the subsequent step, paclitaxel which is a hydrophobic anticancer drug was loaded onto the surface of the functionalized graphene by π-π interactions. The synthesis of the nanocarrier and its interaction with paclitaxel were evaluated by FT-IR, CD, TEM, UV, AFM, DLS and fluorescence experiments. Release of the loaded drug from albumin-graphene conjugate was investigated at pH 5.4, 6.8 and 7.4
Reflection and transmission of obliquely incident graphene plasmons by discontinuities in surface conductivity: Observation of the Brewster-like effect, Article Journal of Optics (United Kingdom) ; Volume 18, Issue 7 , 2016 ; 20408978 (ISSN) ; Rejaei, B ; Khavasi, A ; Sharif University of Technology
Institute of Physics Publishing
Scattering of graphene surface plasmons that are obliquely incident on a line discontinuity in graphene surface conductivity is investigated. The analysis is based on a solution of the quasi-static integral equation for surface charge density. It is shown that the reflection coefficient of the graphene plasmons reaches a minimum at a specific angle of incidence that depends on the ratio of conductivities of the two regions surrounding the discontinuity. This effect, which is similar to the well-known Brewster effect, is pronounced for abrupt discontinuities, but becomes weaker as the width of the transition region increases. The results obtained can be used for the design and analysis of...
Flexible bactericidal graphene oxide–chitosan layers for stem cell proliferation [electronic resource], Article Journal of Applied Surface Science ; 15 May 2014, Volume 301, Pages 456–462 ; Akhavan, O ; Simchi, A. (Abdolreza) ; Sharif University of Technology
Graphene oxide (GO)–chitosan composite layers with stacked layer structures were synthesized using chemically exfoliated GO sheets (with lateral dimensions of ∼1 μm and thickness of ∼1 nm), and applied as antibacterial and flexible nanostructured templates for stem cell proliferation. By increasing the GO content from zero to 6 wt%, the strength and elastic modulus of the layers increased ∼80% and 45%, respectively. Similar to the chitosan layer, the GO–chitosan composite layers showed significant antibacterial activity (>77% inactivation after only 3 h) against Staphylococcus aureus bacteria. Surface density of the actin cytoskeleton fibers of human mesenchymal stem cells (hMSCs) cultured...
Kondo resonance from p-wave hybridization in graphene, Article Journal of Physics Condensed Matter ; Vol. 26, Issue. 41 , 2014 ; SSN: 09538984m ; Tohyama, T ; Sharif University of Technology
The p-wave hybridization in graphene present a distinct class of Kondo problem in pseudogap Fermi systems with bath density of states (DOS) ρ0(ε) ∝ |ε|. The peculiar geometry of substitutional and hollow-site ad-atoms, and effectively the vacancies allow for a p-wave form of momentum dependence in the hybridization of the associated local orbital with the Dirac fermions of the graphene host which results in a different picture than the s-wave momentum independent hybridization. For the p-wave hybridization function, away from the Dirac point we find closed-form formulae for the Kondo temperature TKwhich in contrast to the s-wave case is non-zero for any value of hybridization strength V of...
Interaction of hydrogen molecules with perfect, defective and scandium doped polycyclic aromatic hydrocarbon structures, Article Computational and Theoretical Chemistry ; Volume 1026 , 2013 , Pages 65-71 ; ISSN: 2210271X ; Saboohi, Y ; Sharif University of Technology
In the present work the interaction of hydrogen molecules with perfect, defective and scandium doped polycyclic aromatic hydrocarbon (PAH) has been evaluated. At first the potential barrier for the penetration of hydrogen molecules through PAH structures has been investigated and then the adsorption of hydrogen molecules over PAH structures has been studied. To model the graphene surface for barrier calculations, it is shown that coronene can successfully estimate the graphene monolayer. The barrier height is calculated for perfect and two different defective PAH structures including Stone-Wales (SW) and 585. It is found that PAH even with small defects is impermeable to hydrogen molecules....
Spin effect on band structure of zigzag and armchair graphene nanoribbones with Stone-Wales defect, Article 2013 21st Iranian Conference on Electrical Engineering ; May , 2013 , Page(s): 1 - 4 ; 9781467356343 (ISBN) ; Barami, S ; Sharif University of Technology
In this paper the band structure of spin polarized zigzag graphene nanoribbons(ZGNRs) and armchair graphene nanoribons(AGNRs) with Stone-Wales defect are investigated. The results show when the spin effect is considered, the band structures of ZGNRs and AGNRs will be changed and modified. A larger gap will be created and the degenerate bands in ZGNRs will become far from each other. Tight-binding and hubard model were used to simulate the band structures
Artificial intelligence techniques for modeling and optimization of the HDS process over a new graphene based catalyst, Article Phosphorus, Sulfur and Silicon and the Related Elements ; Volume 191, Issue 9 , 2016 , Pages 1256-1261 ; 10426507 (ISSN) ; Kazemeini, M ; Rashidi, A ; Tayyebi, S ; Sharif University of Technology
Taylor and Francis Ltd 2016
A Co-Mo/graphene oxide (GO) catalyst has been synthesized for the first time for application in a defined hydrodesulfurization (HDS) process to produce sulfur free naphtha. An intelligent model based upon the neural network technique has then been developed to estimate the total sulfur output of this process. Process operating variables include temperature, pressure, LHSV and H2/feed volume ratio. The three-layer, feed-forward neural network developed consists of five neurons in a hidden layer, trained with Levenberg–Marquardt, back-propagation gradient algorithm. The predicted amount of residual total sulfur is in very good agreement with the corresponding experimental values revealing a...
A graphene-based THz ring resonator for label-free sensing, Article IEEE Sensors Journal ; Volume 16, Issue 11 , 2016 , Pages 4338-4344 ; 1530437X (ISSN) ; Safian, R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
In this paper, we report on a novel resonant THz sensor for label-free analysis. The structure consists of a silicon nitride dielectric ring resonator vertically coupled to a thin layer of graphene strip ring resonator on top. The cladding is assumed to be porous alumina on the top of the graphene strip, which enhances the interaction of the surface plasmon wave and the target molecules. Finite difference time domain analysis is used to systematically design the structure and to investigate the performance of the sensor. Our simulations show that the proposed structure has larger refractive index sensitivity and lower intrinsic quality factor with respect to the similar optical structure. It...
Removal of toxic metal ions from sungun acid rock drainage using mordenite zeolite, graphene nanosheets, and a novel metal–organic framework, Article Mine Water and the Environment ; Volume 35, Issue 1 , 2016 , Pages 18-28 ; 10259112 (ISSN) ; Mohaghegh, N ; Sharif University of Technology
Springer Verlag 2016
We evaluated the sorptive properties of mordenite zeolite (MOR), a copper terephthalate metal–organic framework (MOF), and graphene oxide (GO) and their potential use in treating acid rock drainage (ARD) containing Fe3+, Cu2+, Mn2+, Zn2+, Pb2+, and Cd2+ ions. MOR was prepared via a hydrothermal method, MOF was prepared via a solvothermal method, and few-layered GO nanosheets were synthesized using Hummers’ method. The aqueous contaminants were removed by chemico-physical sorption and ion exchange in batch tests. It proved possible to dramatically improve removal efficiency and sorptive capacity by optimizing experimental conditions. Magnetic MOF crystals were more efficient in removing...
Immobilization of dioxomolybdenum(VI) schiff base complex on graphene oxide nanosheets and its catalytic activity for oxidation of sulfides, Article Journal of Coordination Chemistry ; Volume 70, Issue 17 , 2017 , Pages 2986-2998 ; 00958972 (ISSN) ; Karimi, H ; Amini, M ; Sharif University of Technology
Graphene oxide was an effective supporting material for immobilizing a dioxomolybdenum Schiff base complex via covalent interaction. The large surface of graphene oxide plays important roles to obtain a good degree of catalytic reaction. Catalytic capacity of the graphene-bound dioxomolybdenum Schiff base complex was investigated for the oxidation of various sulfides to sulfoxide compounds using hydrogen peroxide urea as an oxidant. The catalyst was characterized by various techniques including XRD, FTIR, TGA, SEM, UV–vis, and ICP-AES. The immobilized complex was very efficient with the extra benefits of easy recovery and recycling of the heterogeneous catalyst. The graphene oxide bound...
Polarization insensitive and broadband terahertz absorber using graphene disks, Article Plasmonics ; Volume 12, Issue 2 , 2017 , Pages 393-398 ; 15571955 (ISSN) ; AbdollahRamezani, S ; Khavasi, A ; Sharif University of Technology
Springer New York LLC 2017
We demonstrate design and characterization of a polarization-independent ultra-broadband absorber of light consisting of periodic array of graphene disks on top of a lossless quarter-wavelength dielectric spacer placed on a metallic reflector. The absorber is duly designed based on impedance matching concept by proposing a fully analytical circuit model resulting in a normalized bandwidth of 100 % in the terahertz regime. © 2016, Springer Science+Business Media New York
Synthesis, characterization and biological evaluation of a well dispersed suspension of gallium-68-labeled magnetic nanosheets of graphene oxide for in vivo coincidence imaging, Article Radiochimica Acta ; Volume 105, Issue 1 , 2017 , Pages 65-73 ; 00338230 (ISSN) ; Rahighi, R ; Tayyebi, A ; Feizi, S ; Sharif University of Technology
Walter de Gruyter GmbH 2017
Graphene oxide (GO) nanosheets were hybridized with Fe3O4 nanoparticles (NPs) to form magnetic GO (MGO) and were further labeled by [68Ga]GaCl3 as a potential drug delivery system. Paper chromatography, Fourier transform infra red (FTIR) spectroscopy, low-angle X-ray diffraction (XRD), CHN and atomic force microscopy (AFM) were utilized to characterize the trinary composite ([68Ga]@MGO). Biological evaluations of the prepared nanocomposite were performed in normal Sprague Dawley rats and it was found to be a possible host for theranostic radiopharmaceuticals. The results showed that the grafting of Fe3O4 NPs on nanocomposite reduced the unwanted liver and spleen uptakes and increased the...
Fabrication of chitosan/poly(lactic acid)/graphene oxide/TiO2 composite nanofibrous scaffolds for sustained delivery of doxorubicin and treatment of lung cancer, Article International Journal of Biological Macromolecules ; 2017 ; 01418130 (ISSN) ; Moradkhani, M ; beheshti, H ; Irani, M ; Aliabadi, M ; Sharif University of Technology
Elsevier B.V 2017
In this work, the synthesized graphene oxide/TiO2/doxorubicin (GO/TiO2/DOX) composites were loaded into the chitosan/poly(lactic acid) (PLA) solutions to fabricate the electrospun chitosan/PLA/GO/TiO2/DOX nanofibrous scaffolds via electrospinning process. The synthesized composites and nanofibers were characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. Three-factor three-level central composite design was used to determine the influence of PLA to chitosan ratio, TiO2/DOX content and GO/TiO2/DOX content on the release of DOX from nanofibrous scaffolds. Drug loading efficiency and drug release behavior from...
Graphene based strain sensors: A comparative study on graphene and its derivatives, Article Applied Surface Science ; Volume 448 , 2018 , Pages 71-77 ; 01694332 (ISSN) ; Bidmeshkipour, S ; Abdi, Y ; Arzi, E ; Mohajerzadeh, S ; Sharif University of Technology
Elsevier B.V 2018
In this study, we have experimentally investigated the electrical properties of graphene and its derivatives (Exfoliated graphene, CVD synthesized graphene, graphene oxide and hydrogenated graphene oxide) under uniaxial strain. We have used gauge factor as a common representation of the sensitivity of the strain sensors and found that the hydrogenated graphene oxide shows significantly higher responsivity comparing to other samples under study. Reproducibility, reliability and lack of hysteresis in the responses of the graphene based samples make them a good candidate to be used in the strain sensors. © 2018
Carbon black-intercalated reduced graphene oxide electrode with graphene oxide separator for high-performance supercapacitor, Article Journal of Nanostructures ; Volume 9, Issue 4 , 2019 , Pages 639-649 ; 22517871 (ISSN) ; Rasuli, R ; Ahadian, M. M ; Mehrabi, B ; Sharif University of Technology
University of Kashan 2019
We present a general study on a high performance supercapacitor based on intercalated reduced graphene oxide with carbon black nanoparticles. Graphene oxide sheets were synthesized by oxidation and exfoliation of natural graphite and were reduced using hydroiodic acid in the presence of carbon black nanoparticles. Graphene paper was fabricated by one-step procedure via simultaneous reducing and drying the aqueous solution of mixed carbon black nanoparticles and graphene oxide on a conductive substrate. Transmission electron microscopy confirmed the intercalation of carbon black nanoparticles into reduced graphene oxide sheets, preventing them from restacking during the fabrication of paper....