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    Nanosheet arrays of TiO2synthesized by one step conversion of ZnO nanosheets: Boosting of electron transport rate and application in dye solar cells

    , Article RSC Advances ; Vol. 4, issue. 85 , 2014 , pp. 45174-45179 ; ISSN: 20462069 Alimirsalari, S ; Tajabadi, F ; Salehkoutahi, S. M ; Ghahary, R ; Taghavinia, N ; Sharif University of Technology
    Abstract
    A TiO2replica of ZnO nanosheet films is synthesized using a chemical replacement process. ZnO nanosheets are grown by electrodeposition on fluorine doped tin oxide (FTO) films, and a dissolution/deposition process is used to convert the ZnO template into a TiO2replica. Electron microscopy shows the final TiO2structure follows the morphology of the initial ZnO template. X-ray diffraction and energy dispersive spectroscopy verify the total transformation of ZnO to TiO2. The as-synthesized TiO2sheets are amorphous and after annealing turn into the anatase phase. The film of TiO2nanosheets is used as the photoanode of a dye sensitized solar cell. Despite the low roughness factor of 100, a... 

    Morphologically tailored CuO photocathode using aqueous solution technique for enhanced visible light driven water splitting

    , Article Journal of Photochemistry and Photobiology A: Chemistry ; Volume 337 , 2017 , Pages 54-61 ; 10106030 (ISSN) Kushwaha, A ; Moakhar, R. S ; Goh, G. K. L ; Dalapati, G. K ; Sharif University of Technology
    Elsevier B.V  2017
    Abstract
    Cupric oxide (CuO) nanostructures are grown on fluorine doped tin oxide (FTO) coated glass substrate using aqueous solution approach. The concentration of precursor's solution has significant impact on morphology of CuO nanostructure. By varying concentration of precursor, the growth of two different morphologies (oriented nanosheets and nanoleaves) is achieved. X-ray diffraction pattern and X-ray photoelectron spectroscopy reveals formation of pure CuO crystalline phase. Mott-Schottky characteristic confirms the p-type semiconducting nature. Ultrathin structures of nanoleaves lead to higher light trapping and light absorption in visible-NIR region. The nanoleaves film has lower bandgap in... 

    Mechanical hydrolysis imparts self-destruction of water molecules under steric confinement

    , Article Physical Chemistry Chemical Physics ; Volume 23, Issue 10 , 2021 , Pages 5999-6008 ; 14639076 (ISSN) Hosseini, E ; Zakertabrizi, M ; Habibnejad Korayem, A ; Carbone, P ; Esfandiar, A ; Shahsavari, R ; Sharif University of Technology
    Royal Society of Chemistry  2021
    Abstract
    Decoding behavioral aspects associated with the water molecules in confined spaces such as an interlayer space of two-dimensional nanosheets is key for the fundamental understanding of water-matter interactions and identifying unexpected phenomena of water molecules in chemistry and physics. Although numerous studies have been conducted on the behavior of water molecules in confined spaces, their reach stops at the properties of the planar ice-like formation, where van der Waals interactions are the predominant interactions and many questions on the confined space such as the possibility of electron exchange and excitation state remain unsettled. We used density functional theory and... 

    Evaluation of viscosity and thermal conductivity of graphene nanoplatelets nanofluids through a combined experimental–statistical approach using respond surface methodology method

    , Article International Communications in Heat and Mass Transfer ; Volume 79 , 2016 , Pages 74-80 ; 07351933 (ISSN) Iranmanesh, S ; Mehrali, M ; Sadeghinezhad, E ; Ang, B. C ; Ong, H. C ; Esmaeilzadeh, A ; Sharif University of Technology
    Elsevier Ltd 
    Abstract
    In the present study, three influential parameters including concentration, temperature and specific surface area of graphene nanosheets were investigated, which are the effective parameters on the viscosity and thermal conductivity of aqueous graphene nanosheets (GNP) nanofluids. A mathematical model developed by respond surface methodology (RSM) based on a central composite design (CCD). Also, the significance of the models was tested using the analysis of variance (ANOVA). The optimum results of aqueous GNP nanofluid showed that the concentration has a direct effect on the relative viscosity and thermal conductivity. Furthermore, predicted responses proposed by the Design Expert software... 

    Biomimetic ultraflexible piezoresistive flow sensor based on graphene nanosheets and PVA hydrogel

    , Article Advanced Materials Technologies ; 2021 ; 2365709X (ISSN) Abolpour Moshizi, S ; Moradi, H ; Wu, S ; Han, Z. J ; Razmjou, A ; Asadnia, M ; Sharif University of Technology
    John Wiley and Sons Inc  2021
    Abstract
    Flow sensors play a critical role in monitoring flow parameters, including rate, velocity, direction, and rotation frequency. In this paper, inspired by biological hair cells in the human vestibular system, an innovative flow sensor is developed based on polyvinyl alcohol (PVA) hydrogel nanocomposites with a maze-like network of vertically grown graphene nanosheets (VGNs). The VGNs/PVA hydrogel absorbs a copious amount of water when immersed in water, making the sensor highly sensitive to tiny stimuli underwater. The sensor demonstrates a high sensitivity (5.755 mV (mm s−1)−1) and extremely low velocity detection (0.022 mm s−1). It also reveals outstanding performance in detecting... 

    Biomimetic ultraflexible piezoresistive flow sensor based on graphene nanosheets and PVA hydrogel

    , Article Advanced Materials Technologies ; 2021 ; 2365709X (ISSN) Abolpour Moshizi, S ; Moradi, H ; Wu, S ; Han, Z. J ; Razmjou, A ; Asadnia, M ; Sharif University of Technology
    John Wiley and Sons Inc  2021
    Abstract
    Flow sensors play a critical role in monitoring flow parameters, including rate, velocity, direction, and rotation frequency. In this paper, inspired by biological hair cells in the human vestibular system, an innovative flow sensor is developed based on polyvinyl alcohol (PVA) hydrogel nanocomposites with a maze-like network of vertically grown graphene nanosheets (VGNs). The VGNs/PVA hydrogel absorbs a copious amount of water when immersed in water, making the sensor highly sensitive to tiny stimuli underwater. The sensor demonstrates a high sensitivity (5.755 mV (mm s−1)−1) and extremely low velocity detection (0.022 mm s−1). It also reveals outstanding performance in detecting... 

    Electrochemical functionalization of graphene nanosheets with catechol derivatives as an effective method for preparation of highly performance supercapacitors

    , Article Electrochimica Acta ; Vol. 147, issue , 2014 , pp. 136-142 ; ISSN: 00134686 Jokar, E ; Shahrokhian, S ; Zad, A. I ; Sharif University of Technology
    Abstract
    Performance enhancement of supercapacitors has been recently discussed. In this paper a novel and facile procedure for functionalization of graphene with some electroactive molecules is presented. The graphene has been functionalized by catechol-based molecules, which are electroactive molecules with electrochemically reversible properties. The functionalized graphene exhibits very effective pseudocapacitor behaviorfor charge storage. For the first time, with the aim of an electrosynthesis procedure, catechol is covalently attached on graphene sheets. This attachment has been investigated by electrochemical, X-ray photoelectron spectroscopy and attenuated total reflectance methods. Catechol... 

    Preparation of conductive polyaniline/graphene nanocomposites via in situ emulsion polymerization and product characterization

    , Article Synthetic Metals ; Vol. 196 , 2014 , pp. 199-205 Baniasadi, H ; Ramazani, S. A ; Mashayekhan, S ; Ghaderinezhad, F ; Sharif University of Technology
    Abstract
    This work, which is a part of our ongoing studies on developing conductive scaffolds for nerve tissue engineering, reports synthesis of highly conductive binary-doped polyaniline nanoparticles and polyaniline/graphene nanocomposites. The samples were synthesized through chemical oxidation of aniline via in situ emulsion polymerization method in presence of hydrochloric acid and sodium dodecyl sulfate. Graphene nanosheets were also prepared via modified Hummer's method followed by chemical reduction using hydrazine monohydrate. Electrical conductivity measurements using a standard four-point probe technique with FTIR and UV-vis studies revealed that conductive binary-doped emeraldine salt... 

    Enzymatic biosensing by covalent conjugation of enzymes to 3D-networks of graphene nanosheets on arrays of vertically aligned gold nanorods: application to voltammetric glucose sensing

    , Article Microchimica Acta ; Volume 185, Issue 3 , 2018 ; 00263672 (ISSN) Mazaheri, M ; Simchi, A ; Aashuri, H ; Sharif University of Technology
    Springer-Verlag Wien  2018
    Abstract
    The authors demonstrate efficient direct electron transfer from the enzyme glucose oxidase to vertically aligned gold nanorods with a diameter of ~160 nm and a length of ~2 μm that are covalently linkage to a 3-dimensional network of reduced graphene oxide nanosheets. The assembly can be prepared by a 2-step electrochemical procedure. This hybrid structure holds the enzyme in a favorable position while retaining its functionality that ultimately provides enhanced performance for enzymatic sensing of glucose without utilizing mediators. The nanorod assembly was applied to the voltammetric detection of glucose. Figures of merit include an electrochemical sensitivity of 12 μA·mM−1·cm−2... 

    Wrapping bacteria by graphene nanosheets for isolation from environment, reactivation by sonication, and inactivation by near-infrared irradiation

    , Article Journal of Physical Chemistry B ; Volume 115, Issue 19 , 2011 , Pages 6279-6288 ; 15206106 (ISSN) Akhavan, O ; Ghaderi, E ; Esfandiar, A ; Sharif University of Technology
    American Chemical Society  2011
    Abstract
    Bioactivity of Escherichia coli bacteria (as a simple model for microorganisms) and interaction of them with the environment were controlled by their capturing within aggregated graphene nanosheets. The oxygen-containing functional groups of chemically exfoliated single-layer graphene oxide nanosheets were reduced by melatonin as a biocompatible antioxidant. While each one of the graphene (oxide) suspension and melatonin solution did not separately show any considerable inactivation effects on the bacteria, aggregation of the sheets in the melatonin-bacterial suspension resulted in trapping the bacteria within the aggregated sheets, i.e., a kind of inactivation. The bacteria trapped within... 

    Magnetite/dextran-functionalized graphene oxide nanosheets for in vivo positive contrast magnetic resonance imaging

    , Article RSC Advances ; Volume 5, Issue 59 , May , 2015 , Pages 47529-47537 ; 20462069 (ISSN) Moradi, S ; Akhavan, O ; Tayyebi, A ; Rahighi, R ; Mohammadzadeh, M ; Saligheh Rad, H. R ; Sharif University of Technology
    Royal Society of Chemistry  2015
    Abstract
    Superparamagnetic iron oxide (SPIO) nanomaterials are widely used as magnetic resonance imaging (MRI) contrast agents (CAs). These CAs significantly shorten transverse relaxation time (T2) and so decrease the intensity of the T2-weighted MRI (negative contrast imaging). However, the partial-volume effect is known to be one of the problems in negative contrast MRI. In this work, SPIO nanoparticles were modified by dextran and graphene oxide (GO) nanosheets to achieve a positive contrast MRI with high intensity. This modification resulted in shortening the longitudinal relaxation time (T1) of the SPIO nanoparticles (in addition to the T2 shortening).... 

    Improvement in mechanical performance of anionic hydrogels using full-interpenetrating polymer network reinforced with graphene oxide nanosheets

    , Article Advances in Polymer Technology ; Volume 35, Issue 4 , 2016 , Pages 386-395 ; 07306679 (ISSN) Kheirabadi, M ; Bagheri, R ; Kabiri, K ; Ossipov, D. A ; Jokar, E ; Asadian, E ; Sharif University of Technology
    John Wiley and Sons Inc 
    Abstract
    Weak mechanical possession is one of the limiting factors in application of hydrogels. To modify this inherent disadvantage, different approaches have been studied including synthesizing interpenetrating polymer network (IPN) and nanocomposite hydrogels. So, this study has focused on preparation of a novel full-IPN structure based on anionic monomers of 2-acrylamido-2-methylpropane sulfonic acid/acrylic acid–sodium acrylate via facile solution polymerization technique in an aqueous media with incorporation of graphene oxide (GO) nanosheets. Mechanical performance of materials in the “as-prepared condition” and “swollen state” was characterized via tensile, compression, and rheology tests,... 

    Composites of reduced graphene oxide/nickel submicrorods for non-enzymatic electrochemical biosensing: application to amperometric glucose detection

    , Article Journal of the Electrochemical Society ; Volume 167, Issue 8 , 2020 Mohammadzadeh, A ; Mazaheri, M ; Sedighian, A ; Ghanbari, H ; Simchi, A ; Sharif University of Technology
    Institute of Physics Publishing  2020
    Abstract
    For the rapid detection of hyperglycemia in human blood, we adopted a facile and two-step electrochemical procedure to prepare nickel/reduced graphene oxide (rGO) hybrid electrodes in the framework of a three-dimensional (3D) nanostructure. High-density and vertically-aligned nickel submicrorods with an average diameter of 155 ± 15 nm and a length of 7 ± 1 μm (an aspect ratio of about 40-50) were prepared by template-mediated electrochemical deposition techniques. Networks of rGO nanosheets between the rod-shaped arrays were formed by the cathodic electrophoretic deposition method. The synergistic effect of nickel morphology (planar and high-density rod-shaped arrays) and graphene oxide... 

    On the mechanical characteristics of graphene nanosheets: A fully nonlinear modified Morse model

    , Article Nanotechnology ; Volume 31, Issue 11 , 2020 Shoghmand Nazarloo, A ; Ahmadian, M ; Firoozbakhsh, K ; Sharif University of Technology
    Institute of Physics Publishing  2020
    Abstract
    In this paper, the mechanical properties of graphene nanosheets are evaluated based on the nonlinear modified Morse model. The interatomic interactions including stretching and bending of the covalent bonds between carbon atoms, are replaced by nonlinear extensional and torsional spring-like elements. The finite element method is implemented to analyze the model under different loading conditions and linear characteristics of the graphene structure including the Young's modulus, surface modulus, shear modulus and Poisson's ratio are evaluated for various geometries and chirality where these properties are shown to be size and aspect ratio dependent. It is also found that when the dimensions... 

    Hybrid of cerium dioxide nanoparticles/reduced graphene oxide as an electrode material for supercapacitor applications

    , Article Journal of Physics and Chemistry of Solids ; Volume 159 , 2021 ; 00223697 (ISSN) Salarizadeh, P ; Askari, M. B ; Beydaghi, H ; Rastgoo Deylami, M ; Rozati, S. M ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    In this study, we prepared cerium oxide (CeO2) hybridized with reduced graphene oxide (rGO) nanosheets using the hydrothermal method. CeO2 and CeO2/rGO were evaluated as electrode materials for use in supercapacitor applications. The structure and morphology of the synthesized materials were investigated. Cyclic voltammetry tests determined a high specific capacitance of 581 F g−1 for CeO2/rGO at a scan rate of 10 mV s−1 in 2 M KOH. In addition, the CeO2/rGO electrode retained 91 % of its initial capacitance after 5000 consecutive cycles, thereby indicating its excellent electrochemical stability. The excellent stability of CeO2/rGO was due to a synergistic effect between CeO2 and rGO. CeO2... 

    Vibration Analysis of Orthotropic Graphene Sheets Using Nonlocal Elasticity Theory in Elastic Support With Different Boundary Conditions

    , M.Sc. Thesis Sharif University of Technology Bayati, Mohammad Reza (Author) ; Dehghani Firouzabadi, Rohollah (Supervisor)
    Abstract
    Nanotechnology with the tools, materials and their applications in areas such as engineering mechanics, materials, electronics, computers, and machines at the nanoscale is dealing. The Fnarvy, atoms and molecules as building materials, engineering bricks counts. In mechanical engineering branch, two aspects are discussed in view of nanotechnology, nano-scale structures and analyzing the behavior of phenomena that occur at the nanoscale. In this project, methods to analyze the behavior of nanoscale materials has been studied.
    The present thesis examines the natural frequencies of nano graphene sheets on elastic foundation deals. The elastic foundation modeled with two springs.At first The... 

    A degree based topological study of two carbon nanosheets and nanosheets VC5C7 and HC5C7

    , Article Polycyclic Aromatic Compounds ; 2021 ; 10406638 (ISSN) Ishtiaq, M ; Rauf, A ; Rubbab, Q ; Siddiqui, M. K ; Rehman, A. U ; Cancan, M ; Sharif University of Technology
    Bellwether Publishing, Ltd  2021
    Abstract
    Nanomaterials are chemical compounds or substances which are moderately produced and used. Nanomaterials are engineered to reveal novel properties of nanocells that contrast with related non-visible substances, such as expanded consistency, conductivity or synthetic reaction. Topological indexes are quantities related to molecules that capture the harmony of molecular structures and give scientifically related properties, such as: viscosity, boiling point, radius of gravity, and so on. Their demands in genetics, chemistry, physics and nanoscience are infinite. The molecular topology of such compounds would be clarify by the quantitative structure properties relationship (QSPR) and... 

    Plasma surface functionalization of boron nitride nano-sheets

    , Article Diamond and Related Materials ; Volume 77 , 2017 , Pages 110-115 ; 09259635 (ISSN) Achour, H ; Achour, A ; Solaymani, S ; Islam, M ; Vizireanu, S ; Arman, A ; Ahmadpourian, A ; Dinescu, G ; Sharif University of Technology
    Elsevier Ltd  2017
    Abstract
    On silicon substrates, boron nitride nanosheets (BNNS) consisting of interconnected hexagonal boron nitride nano-layers were produced via chemical vapor deposition process at 1200 °C whose roughness's are at the micrometer- and nanometer-scale. The BNNS were functionalized in argon plasma admixed with ammonia or nitrogen or oxygen. The samples were characterized to investigate the surface chemistry and structural changes after plasma treatment using X-ray photoelectron spectroscope and Micro-Raman spectroscope techniques, respectively. While no significant changes in the surface features, upon plasma treatments of the BNNS, were noticed during SEM and TEM examination, the oxygen functional... 

    Al doped ZnO NanoStructures by Electrodeposition & Solvothermal for Dye Sensitized Solar Cells Application

    , M.Sc. Thesis Sharif University of Technology Ghahary, Raheleh (Author) ; Taghavinia, Nima (Supervisor)
    Abstract
    ZnO semiconductor has a wide band gap (3.3eV) and high electron mobility, making it a possible candidate for an effective structure-based Dye-sensitized solar cell (DSSC) semiconductor. Efficiency of DSSC based on ZnO is lower than TiO2 due to its low chemical satability. It is well known that the energy conversion efficiency of DSSC depends on the electron transport in the photoelectrode so in this investigation we fabricated high transport photoelectrode by doping Al in ZnO nanostructures. DSSC based on Al doped and undoped ZnO nanosheet synthesized by electrochemical deposition. Current density-voltage (J-V) characterizations indicate that Al-doping in ZnO crystal structure increases... 

    Preparation of Nanocomposites from Carbon Nanostructures and Transtion Metal Oxides and their use in Preparation of Hybrid Electrochemical Capacitors

    , M.Sc. Thesis Sharif University of Technology Rahimi, Sajad (Author) ; Shahrokhian, Saeed (Supervisor)
    Abstract
    In the first part, we report a new and simple procedure for preparing reduced graphene oxide /nickel, cobalt hydroxide composite (Ni,Co-OH/rGO/NF via a fast and simple two-step electrochemical method including potentiostatic routes in the presence of Cetyl trimethyl ammonium bromide )CTAB( as a cationic surfactant. In the first step, a piece of nickel foam (NF) is sonicated in a suspension of graphene oxide (GO, 6 mg/L) after dried in an oven, reduced by electrochemically. After that, Ni, Co LDH were co-deposited on the surface of rGO/NF. The resulting modified electrode afforded extremely high specific capacitance of 2133.3 F/g at a current density of 4 A g-1. FE-SEM results showed that...