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Poly (vinyl alcohol)/graphene oxide nanocomposite films and hydrogels prepared by gamma ray
, Article Plastics, Rubber and Composites ; Volume 48, Issue 2 , 2019 , Pages 42-47 ; 14658011 (ISSN) ; Dadbin, S ; Tabatabaei, M ; Sharif University of Technology
Taylor and Francis Ltd
2019
Abstract
Poly (vinyl alcohol)/graphene oxide (PVA/GO) gamma irradiated nanocomposite films and hydrogels were prepared. In composite films, GO was initially irradiated by gamma ray in order to improve interactions between GO and PVA. The film containing 1 wt-% GO was very strong where tensile modulus and tensile yield strength were 45 and 115% higher than those of pure PVA. In the second set of experiments PVA/GO hydrogels were made by irradiating PVA/GO suspensions by gamma ray at various doses. It was an interesting finding that GO increased the gel portion of hydrogels through contribution of H-bonds between PVA and GO. The hydrogels prepared at 20 kGy had remarkable water swelling ratio that...
Structural, microstructural and electrochemical studies of TiO2-Ag double layer coated NCM cathode for lithium-ion batteries
, Article Materials Research Express ; Volume 6, Issue 8 , 2019 ; 20531591 (ISSN) ; Ghorbanzadeh, M ; Sharif University of Technology
Institute of Physics Publishing
2019
Abstract
Lithium ion batteries as one of the most important energy storage equipments, have several challenges including capacity drop as number of cycles increases. Cathode particle coating is an effective approach in improvement of electrochemical performance of the batteries. In this study, TiO2-Ag coating was used to improve NCM cathode performance. The microstructure and crystal structure properties of coated NCMs were evaluated by the FE-SEM and XRD. Electrochemical behavior of the batteries was investigated by cycling performance analysis and EIS. TiO2 coating was deposited as a uniform layer and Ag coating was precipitated as dispersed nanoparticles. The results shows that using of TiO2-Ag...
Fabrication, characterization, and electrochemical performance of the hdpe/sepiolite nanocomposite as a novel separator for li-ion batteries
, Article Express Polymer Letters ; Volume 15, Issue 11 , 2021 , Pages 1063-1080 ; 1788618X (ISSN) ; Pircheraghi, G ; Sharifi, H ; Sharif University of Technology
BME-PT and GTE
2021
Abstract
Separators are one of the most critically important components of lithium-ion batteries to ensure the safe performance of the battery. Commercial polyolefin separators have high thermal shrinkage and low electrolyte uptake, which confines the application of the battery. By using the thermally induced phase separation (TIPS) method, we successfully prepared HDPE/sepiolite nanocomposite separators with high thermal stability and electrolyte wettability. The sepiolite nanofibers are modified with the Vinyltriethoxysilane (VTES) as a coupling agent for better dispersion and interaction in the HDPE matrix. The purpose of fabricating this separator is to decrease the thermal shrinkage and...
Cycling performance of LiFePO4/graphite batteries and their degradation mechanism analysis via electrochemical and microscopic techniques
, Article Ionics ; 2021 ; 09477047 (ISSN) ; Mosallanejad, B ; Mohammadzad, M ; Hosseini Hosseinabad, S. M ; Ramakrishna, S ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
In this work, cycling-induced aging occurring in 18650-type LiFePO4/graphite full cells at different C-rates is studied extensively. The mechanism of performance degradation is investigated using a combination of electrochemical and microstructural analyses. Half-cell studies are carried out after dismantling the full cells, using fresh and cycled LiFePO4 cathode and graphite anode to independently study them. The results show that the capacity of LiFePO4 electrodes is significantly recovered. The rate of capacity fading in the discharge state considered as irreversible capacity in the graphite is higher than LiFePO4 half cells, indicating a greater degradation in the performance of this...
Spinel H4Ti5O12 nanotubes for Li recovery from aqueous solutions: Thermodynamics and kinetics study
, Article Journal of Environmental Chemical Engineering ; Volume 9, Issue 1 , 2021 ; 22133437 (ISSN) ; Ghasemi, S ; Askari, M ; Khosravi, A ; Hasan Zadeh, A ; Alamolhoda, A. A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In this study, H4Ti5O12 nanotubes have been prepared as Li+ adsorbent by acid treatment of Li4Ti5O12 nanotubes. Li4Ti5O12 nanotubes were synthesized via a hydrothermal method in which TiO2(B) nanNotubes were used as a precursor. The prepared Li-ion sieve showed a significant high ion-exchange capacity (160.6 mgg−1) for lithium ions due to its large specific surface area of 115.4 m2 g-1 compared to the other related studies. The kinetics and isotherm investigation revealed that the pseudo-second-order equation well described the adsorption kinetics, and the Langmuir model well fitted the isotherm data. Furthermore, the low value of adsorption energy obtained from the Dubinin-Radushkevitch...
Facile synthesis and simulation of MnO2 nanoflakes on vertically aligned carbon nanotubes, as a high-performance electrode for Li-ion battery and supercapacitor
, Article Electrochimica Acta ; Volume 390 , 2021 ; 00134686 (ISSN) ; Abnavi, A ; Ghasemi, F ; Ghasemi, S ; Sanaee, Z ; Mohajerzadeh, S ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
This study reports the successful fabrication of high-performance flexible binder-free lithium-ion battery anode and supercapacitor based on the synthesis of 3D hierarchical MnO2 nanoflakes (NFs) on vertically aligned carbon nanotubes (VACNTs) grown upon stainless steel (SS). The experimental results revealed that the prepared electrodes were well served as supercapacitors with a tremendous specific capacitance of MnO2 NFs VACNT/SS 1131 F/g at 0.25 A/g in 0.5 mol.L−1 Na2SO4, 518.8% more than VACNT/SS (218 F/g). Compared to other MnO2 NFs/CNT composites, as-fabricated binder-free MnO2 NFs/VACNTs electrode achieves outstanding performance with high initial discharge and charge capacities of...
Facile synthesis and simulation of MnO2 nanoflakes on vertically aligned carbon nanotubes, as a high-performance electrode for Li-ion battery and supercapacitor
, Article Electrochimica Acta ; Volume 390 , 2021 ; 00134686 (ISSN) ; Abnavi, A ; Ghasemi, F ; Ghasemi, S ; Sanaee, Z ; Mohajerzadeh, S ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
This study reports the successful fabrication of high-performance flexible binder-free lithium-ion battery anode and supercapacitor based on the synthesis of 3D hierarchical MnO2 nanoflakes (NFs) on vertically aligned carbon nanotubes (VACNTs) grown upon stainless steel (SS). The experimental results revealed that the prepared electrodes were well served as supercapacitors with a tremendous specific capacitance of MnO2 NFs VACNT/SS 1131 F/g at 0.25 A/g in 0.5 mol.L−1 Na2SO4, 518.8% more than VACNT/SS (218 F/g). Compared to other MnO2 NFs/CNT composites, as-fabricated binder-free MnO2 NFs/VACNTs electrode achieves outstanding performance with high initial discharge and charge capacities of...
Magnetic stirring assisted hydrothermal synthesis of Na3MnCO3PO4 cathode material for sodium-ion battery
, Article Ceramics International ; Volume 47, Issue 19 , 2021 , Pages 26929-26934 ; 02728842 (ISSN) ; Sadrnezhaad, S.K ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Na3MnCO3PO4 (NMCP) is considered one of the promising cathode materials for sodium-ion batteries due to its high theoretical capacity. The hydrothermal method is an efficient, environmental-friendly, and simple route with low instrument cost to prepare active cathode materials such as NMCP. In this research, magnetic stirring was applied to promote the hydrothermal synthesis, and NMCP was produced by controlling different stirring times. This method results in the formation of pure NMCP upon only 45 min processing time. According to the ICP results, the Na to Mn ratio in the NMCP approached the stoichiometric value of 3 by prolonging the stirring time. By analyzing the charge-discharge...
Lithium Extraction with TiO2 Nanotube Synthesized by Anodizing Method
, M.Sc. Thesis Sharif University of Technology ; Askari, Masoud (Supervisor)
Abstract
Due to the technology advancement and the large-scale application of lithium-ion batteries in recent years, the market demand for lithium is growing rapidly and the availability of land lithium resources is decreasing significantly. As such, the focus of lithium extraction technologies has shifted to water lithium resources involving salt-lake brines and sea water. The ion exchange process is a promising method for lithium extraction from brine and seawater having low concentrations of this element. Among various aqueous recovery technologies, the lithium ion-sieve (LIS) technology is considered the most promising one. This is because LISs are excellent adsorbents with high lithium uptake...
Quick speciation of iron(II) and iron(III) in natural samples using a selective fluorescent carbon dot-based probe
, Article Analytical Methods ; Volume 8, Issue 20 , 2016 , Pages 4064-4068 ; 17599660 (ISSN) ; Taghipour, M ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
A new, simple and rapid carbon dot (CD) based fluorescent probe for speciation of Fe2+ and Fe3+ ions was developed. The as-prepared CDs contain phenol groups on their surfaces and due to the special coordination interaction of phenol groups with Fe3+ ions, this sensing system exhibits excellent sensitivity and selectivity toward Fe3+. In order to detect Fe2+ ions as well, a specific amount of H2O2 was introduced to the detection system to transform Fe2+ to Fe3+ of which the latter is the determinable form of iron. Under the optimum experimental conditions, the fluorescence intensity of the sensor decreased as the Fe3+ ion concentration increased. The relationship plot between the...
Effect of asphaltene and resin on interfacial tension of acidic crude oil/ sulfate aqueous solution: Experimental study
, Article Fluid Phase Equilibria ; Volume 414 , 2016 , Pages 149-155 ; 03783812 (ISSN) ; Ayatollahi, S ; Sharif University of Technology
Elsevier
2016
Abstract
Although the capability of using sulfate anion as a wettability modiffier is well established, no systematic investigation on the effect of sulfate ions and natural surfactants in the crude oil including asphaltene and resin on the interfacial tension (IFT) of acidic crude oil (ACO)/sulfate were performed. In this regards, the fluid/fluid interactions are tested through the IFT measurements for ACO, asphaltene and resin extracted from ACO in the presence of sulfate salts including Na2SO4, MgSO4 and CaSO4 while the concentration of each salt ranges between 0 and 45000 ppm. The obtained results demonstrate that the capability of asphaltene molecules is higher for IFT reduction compared with...
Possibility of methane conversion into heavier hydrocarbons using nanosecond lasers
, Article Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy ; Volume 156 , 2016 , Pages 118-122 ; 13861425 (ISSN) ; Irani, E ; Sadighi Bonabi, R ; Sharif University of Technology
Elsevier
2016
Abstract
Effect of nanosecond lasers on the methane dissociation is experimentally studied by using three different laser wavelengths at 248 nm, 355 nm and 532 nm. C2H2 generation is measured as a major reaction product in experiments and the energy consumptions in production of this component are measured as 5.8 MJ/mol, 3.1 MJ/mol and 69.0 MJ/mol, for 355 nm, 532 nm and 248 nm wavelengths, respectively. The mechanism of conversion and production of new stable hydrocarbons is also theoretically investigated. It is found that in theoretical calculations, the ion-molecule reactions should be included and this leads to a unique approach in proper explanation of the experimental measurements
Synthesis parameters effect on the final morphology of the layered double hydroxide (LDH)
, Article Protection of Metals and Physical Chemistry of Surfaces ; Volume 53, Issue 3 , 2017 , Pages 460-465 ; 20702051 (ISSN) ; Afshar, A ; Sharif University of Technology
Maik Nauka Publishing / Springer SBM
2017
Abstract
Smart coatings which prevent corrosion by several mechanisms recently have been carefully planned. One of these mechanisms is the use of ion exchangers like LDH in the coating network. Since the morphology is the most important properties for the applications that the surface plays an important role, LDH morphology was evaluated in this study. For this purpose, the LDH contain a kind of green inhibitor was synthesized and after evaluating its performance it was examined morphologically by changing significant parameters like MII/MIII, pH, aging time and temperature. It is found that, high ratio of the MII/MIII cause thinner layer of LDH. The pH also has special effect on the surface...
Photo-Fenton like degradation of catechol using persulfate activated by UV and ferrous ions: Influencing operational parameters and feasibility studies
, Article Journal of Molecular Liquids ; Volume 249 , 2018 , Pages 463-469 ; 01677322 (ISSN) ; Takdastan, A ; Borghei, S. M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
In the present study, photo-Fenton degradation of catechol from aqueous solution was carried out using UV light and iron ions (Fe2+) as activators of persulfate (PS). Catechol degradation from solution was studied under different experimental variables such as solution pH (2.0–10.0), iron dosages (0.1–0.5 g/L), persulfate loadings (1.0–5.0 mM), initial catechol concentrations (20–100 mg/L) and scavengers (TBA and IPA). The comparative study of catechol removal showed that among the applied approaches, the order of degradation of catechol is as follows: PS/Fe2 +/UV > PS/Fe2 + > UV/PS > PS > UV. Furthermore, higher catechol degradation was observed with increasing iron dosage and PS...
An inhomogeneous theory for the analysis of an all-optical gain-stabilized multichannel erbium-doped fiber amplifier in the presence of ion pairs
, Article Optical Fiber Technology ; Volume 14, Issue 1D , 2008 , Pages 54-62 ; 10685200 (ISSN) ; Keyvaninia, S ; Karvar, M ; Sharif University of Technology
Academic Press Inc
2008
Abstract
In this paper the gain dynamics of an all-optical gain-clamped multichannel erbium-doped fiber amplifier (EDFA) with an inhomogeneous active medium in the presence of ion pairs is modeled. A two-level model for single ions and a three-level model for ion pairs are used to drive the propagation and rate equations of inhomogeneous laser medium. The governing equations are an uncountable system of partial differential equations (PDEs). Using the moment method, the system of PDEs is converted to a finite system of ordinary differential equations (ODEs). The solution of the system of ODEs is used to analyze the gain dynamics of all-optical gain-stabilized multi-wavelength heavy doped EDFA....
Synthesis and study of a new class of red pigments based on perovskite YAlO3 structure
, Article Ceramics International ; Volume 33, Issue 8 , December , 2007 , Pages 1427-1433 ; 02728842 (ISSN) ; Faghihi Sani, M. A ; Mirhabibi, A ; Sharif University of Technology
2007
Abstract
A red pigment has been prepared by substituting chromium ions in aluminum ion sites in YAlO3 perovskite structure. In a first step, effect of various mineralizers on YAlO3 formation has been investigated, which resulted in decrease of formation temperature down to 1400 °C. In the next step, a red pigment corresponding to YAl1-yCryO3 (y = 0.05), has been prepared by heating a mixture containing Y2O3, Al2O3 and Cr2O3 at 1500 °C for 6 h. Later, effect of the doped chromium amount on the pigment redness (a*) has been studied. The highest redness has been obtained when y was 0.04(YAl1-yCryO3). Application of the prepared red pigment in low and high temperature glazes, demonstrated its high...
Electrical properties of nanocontacts on silicon nanoparticles embedded in thin SiO2 synthesized by ultralow energy ion implantation
, Article Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures ; Volume 23, Issue 6 , 2005 , Pages 2821-2824 ; 10711023 (ISSN) ; Shalchian, M ; Coffin, H ; Claverie, A ; Grisolia, J ; Dumas, C ; Atarodi, S. M ; Sharif University of Technology
2005
Abstract
In this paper, we present the room temperature current-voltage characteristics of large (100×100 μ m2) and a nanoscale (100×100 nm2) metal-oxide-semiconductor (MOS) capacitor containing few silicon nanocrystals. The layer of silicon crystals is synthesized within the oxide of this capacitor by ultralow energy ion implantation and annealing. Current fluctuations in the form of discrete current steps and sharp peaks are apparent in the static and dynamic I (V) characteristics of the capacitor. These features have been associated to quantized charging and discharging of the nanoparticles and the resulting Coulomb interaction to the tunneling current. © 2005 American Vacuum Society
Application of the GV-MSA model to the electrolyte solutions containing mixed salts and mixed solvents
, Article Fluid Phase Equilibria ; Volume 231, Issue 1 , 2005 , Pages 67-76 ; 03783812 (ISSN) ; Taghikhani, V ; Ghotbi, C ; Sharif University of Technology
2005
Abstract
In this work the Ghotbi-Vera mean spherical approximation (GV-MSA) model, coupled with two different expressions for the cation-hydrated diameters, was used in predicting the mean ionic activity coefficients (MIAC) of electrolytes for a number of the mixed-solvent and mixed-salt electrolyte solutions at 25 °C. In all cases the cation diameters in solutions changed with concentration of electrolyte while the anion diameters were considered to be constant and equal to the corresponding Pauling diameters. In application of the GV-MSA model to the electrolyte systems, two different expressions were used for concentration dependency of cation-hydrated diameters, i.e., the GV-MSA1 and GV-MSA2...
, M.Sc. Thesis Sharif University of Technology ; Pourjavadi, Ali (Supervisor) ; Zohurian Mehr, Mohammad Jalal (Supervisor)
Abstract
Polyampholyte hydrogels are hydrophilic networks that contain both positively- and negatively-charged functional groups on their structure. Polysulfobetaines are the most important type of polyampholytes, which have been extensively studied. However, these hydrogels exhibited poor gel strength causing limitation of their applications. Consequently, much attention has been focused on the preparation of nanocomposite hydrogels with high gel strength and lower cost using organomodified clays. In this project, Novel polyampholytic superabsorbing nanocomposites based on the zwitterionic sulfobetaine monomer [3-(methacrylamido)propyl)]dimethyl(3-sulfopropyl) ammonium hydroxide (MPDSAH) were...
An Investigation About Using Engineering Polymers, Polycarbonate and Polysulfone, as Membrane in Fuel Cells
, M.Sc. Thesis Sharif University of Technology ; Ramazani Saadatabadi, Ahmad (Supervisor) ; Musavi, Abbas (Supervisor)
Abstract
In this work, sulfonated polycarbonate (SPC ) membranes with different acid contents have been prepared by conducting sulfonation reaction at room temperature using Chlorosulfonic acid (CSA) as sulfonating agent at different concentration of acid in reacting solution. The SPC membranes were obtained by casting from 10% solution of SPC in chloroform at room temperature. The prepared membranes were characterized using Ion exchange capacity (IEC), and degree of sulfonation (DS), Fourier Transform Infrared (FTIR), NMR spectra, Thermal Gravimetric Analysis (TGA) and Water uptake. The obtained results showed that with increaseing in Chlorosulfonic acid content in sulfonation reaction IEC and DS of...