Sharif Digital Repository

Unique and interesting properties of Graphene with two dimentional and CarbonNanotubes rod-like and their increasing applications such as application in electronic industry, sensors, displays, supercapasitors, pharmacy, etc, they hase become an important field of condensed matter and nanotechnology. Crystalization process and the distribution of light atoms and molecules on graphene surface hase become one of the reaserche arease of interest and hase attracted much attention. These studies play an important role in design of nanosensors graphene based. Most of the experimental observatins of surface diffusion in the chemical and physics systems have been classically described and... 

In this project, the photoelectrochemical properties of ZnO nanostructures modified by CdS and Graphene was studied. Firs, titanium foil was cut into rectangular shape with 1cm width and 3 cm length, cleaned by rinsing in acetone and ethanol and annealed at 4000C for an hour. As a result, a thin layer of titanium oxide was formed on Ti sheet. Then a layer of grapheme oxide was deposited on substrate using Electrophoretic deposition (EPD). After that, ZnO nanostructure was deposited on the TiO2 substrate using Electropulsation (EP) with 20 consecutive pulse followed by 3 minutes Electrodeposition (ED). Using SEM analysis, the morphology of ZnO was determined to be nanopetals in which the... 

Nowadays, there is no perfect drug delivery for cancer therapy; also the healthy tissues can be damaged more than tumor tissues. To resolve this problem, the new drug delivery system based on nanostructured materials is useful. Graphene oxide (GO) is one of the most important graphene derivatives and a potential candidate for drug delivery system. It has high specific surface area so that it can load and deliver the drug in a good manner. Hydrophobicity of graphene restricts its application in nanomedicine. In order to improve its solubility in water, graphene should be modified by hydrophilic polymers. Therefore, in this study, in order to activate the graphene surface and increase its... 

A series of V2O5 catalysts supported on multiwall carbon nanotube (MWCNT), single wall carbon nanotube (SWCNT) and graphene were synthesized by hydrothermal and reflux methods for oxidative dehydrogenation of propane (ODHP) to propylene. The catalysts were characterized by techniques including the BET surface area measurements, XRD, FTIR, H2-TPR, NH3-TPD, FESEM and UV-vis diffuse reflectance. The performance of the catalysts and the supports were subsequently examined in a fixed bed reactor. The vanadium catalyst supported on graphene with C/V molar ratio of 1:1 synthesized through the hydrothermal method had the best performance under the reactor test conditions of 450°C, feed C3H8/Air... 

In this thesis, the thermal and thermoelectric properties of graphene-based nanostructures are numerically investigated. The transport parameters, including Seebeck coefficient, electrical conductance, and thermal conductance are obtained as well as the thermoelectric figure of merit. The Hamiltonian matrix is set up using a third nearestneighbor atomistic tight-binding approximation and the dynamical matrix using a 4th nearest neighbor force constant approximation. Both ballistic and diffusive regimes are considered in this work. For transport investigation, the Landauer formula and the nonequilibrium Green’s function techniques are used. The role of temperature, geometrical parameters,... 

Supercapacitors represent a new class of energy storage devices that have been attracted many researchers in last few years. Graphene with unique properties such as superior electrical conductivity and large specific surface area is one of the most suitable materials in supercapacitor applications. Besides, metal oxides are being used as active compounds in supercapacitors due to their role in redox reactions. In this research, synthesis and characterization of supercapacitor electrodes based on graphene and MnO2 nanostructured materials was studied under different conditions. For this purpose, Graphene oxide (GO) was synthesized by Hummers’ method and then, it was deposited on a nickel foam... 

Nowadays, because of the importance of saving energy resources and also environmental issues, utilization of catalysts are increased in industry and products. In the last decades, a lot of efforts have been devoted to develop novel methods for heterogenizing of the homogeneous catalyst in order to combine the advantages of the both the homogeneous and the heterogeneous catalysts. Among the different solid supports, graphene with high surface area and distinctive mechanical and electronical properties have been introduces as an emerging support for heterogenizing of the homogeneous catalysts. On the other hand, the use of ionic liquid has been developed due to a broad range of polarity, low... 

In this thesis we have been mainly interested in studying Single Impurity Anderson model (SIAM) in Dirac fermions. Although this model seems to be simple, the rich physics of SIAM can not be underestimated. In this thesis we were interested in Dirac materials, systems which their low energy excitations are described by Dirac equation.Therefore, considering Dirac material in two dimensions(2D), we briefly review the distinct features of one atom thick layer of carbon. In addition, we will explain the effective Hamiltonian of Bismuth near L point which is considered a three dimensional(3D) Dirac material. Because of very strong spin-orbit interaction, bismuth is a key element in topological... 

These days, technological advances and industrial expansion cause to increase environmental pollution. Using different kinds of chemicals in textile industries, agriculture, ... led to enter huge amount of pollutant to natural ecosystems, especially in aquatic ecosystems. Advanced oxidation processes (AOPs) based on the generation of very reactive species such as hydroxyl radicals (•OH) oxidize a broad range of pollutants quickly and non selectively. Among AOPs, heterogeneous photocatalysis using TiO2 as photo-catalyst appears as the most emerging destructive technology. In this project, TiO2 nanostructured hybrid materials were synthesized as photocatalysts by various methods including... 

Graphene, a monolayer carbon-atomic honeycomb lattice crystal, has attracted attention due to its peculiar carrier transport properties owing to the gapless energy spectrum. Due to lack of applicable light source in terahertz (THz) band, further researches to finding materials that are suitable for semiconductor lasers in this band to be continued. In this thesis, the population inversion possibility that is the first provision of laser operation, was analyzed in graphene optical pumping situation. The analysis was done by numerical solving of carrier concentration and energy density relations.As a result of this analysis population inversion is obtained when the stimulation square pulse has... 

Sodium-ion batteries are cost-effective rechargeable batteries which have attracted considerable interest in recent years due to the low cost and abundance of sodium resources on the earth. Na3MnCO3PO4 (NMCP) has been identified as a potential cathode material with a high theoretical capacity of 191 mAh g-1. In order to improve the conductivity and electrochemical properties of NMCP, fabrication of NMCP/reduced graphene oxide (rGO) composite is a novel and interesting research goal. Therefore, in the current study, rGO was produced by using modified Hummers method. Then, the kinetics of NMCP formation through hydrothermal process was investigated. Results indicate that the optimum... 

The main object of the presented thesis is manufacturing ultra high molecular weight polyethylene(UHMWPE)/Graphene nanocomposites by insitu polymerization using Ziegler Natta catalysts. In this study, three types of Ziegler Natta Catalysts such as Magnesium ethoxide supported, single-supported and bi-supported have been studied. Experimental conditions are optimized (from point of productivity and molecular weight) by Design expert software with response surface methodology (Box-Behnken design). Effect of process parameters like temperature, pressure and [Al]/[Ti] molar ratio on productivity and Molecular weight are investigated. Also, the effect of hydrogen presence and type of cocatalyst... 

Due to the growing need for plasmonic wavs in microwave and terahertz spectra, a periodic arrangement of one-dimensional cut-through slits is investigated and an equivalent model based on the effective medium theory is derived. In contrast to the all previous attempts that were successful in mimicking only the zeroth-order diffracted waves, the proposed effective medium is capable of mimicking all diffraction orders. The parameters of the equivalent model are established by comparing the scattered waves of the semi-homogeneous medium and those of the main structure obtained by invoking the rigorous mode matching approach based on the single mode approximation inside the slits. This medium is... 

World population growth, depletion of fossil fuels resources depletion and increased air pollution resulting from their consumption, human society has had to replace fossil fuels with renewable sources. In this context, the production of hydrogen using solar energy is feasible candidate to replace fossil fuels, which can be produced by water splitting in a photoelectrochemical (PEC) cell using an appropriate photocatalyst. This clean production method has been attended by many researchers in recent years. The most common photocatalyst for the conversion of sunlight to hydrogen by splitting water is Titanium dioxide (TiO2). But high energy gap and fast electron-hole recombination rate in TiO2... 

In this thesis the graphene-based magnetic nanocatalyst was synthesized. The surface of this catalyst was cavered by silica and AgNPs. In addithion of simple sepration by magnetbar, yeild of reaction was promoted by surface modification. Catalyst structure was verified by transmission electron microscopy , scanning electron microscope, fourier transform infrared spectroscopy, X-ray diffraction and Energy dispersive spectroscopy.At the end catalytic activity was examined by oxidation reaction in persense of different alcohols. The oxidation of benzylic alcohol with electron withdrawing substituents was more difficult and the yield was lower, but electron donor substituents effect positively... 

Solar energy is one of the man's solutions to cope with problems involved in exhaustible fossil resources. In this regard, using photocatalysts is a practical and rational pproach.Nanotechnology facilitates using catalysts and photocatalysts with more productivity.TiO2 semiconductor is one of the most popular material in this field but its efficiency is low by several factors such as being inactive in visible light, recombination and the high cost of using noble metals. In this research, we tried to fix these limitations by creating a p-n junction TiO2 - NiO nanocomposite. The samples are made by three methods: impregnation, ultrasonic assisted modified impregnation with ammonium hydroxide... 

One atom thick layer of pure carbon in bonded and hexagonal lattice is named graphene. graphene has unique mechanical, optical, thermal and electrical properties and because of these properties has grabbed attention. graphene has been made from high pure graphite by different methods such as CVD(chemical vapor deposition) , chemical exfoliation , micromechanical cleavage and colloidal suspension. through these methods, green methods for synthesis of graphene, using eco-friendly reductants during synthesis of graphene instead of hydrazine and recently using waste(not graphite) are attractive for synthesis of graphene. Following this idea , a group has produced graphene from wastes such as... 

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... 

This thesis is divided into three parts: In part I, structure and electronic properties of ionic liquids based on N7, N9-dimethylguaninium cation and α-amino acid (Gly, His, Phe, Try, and Tyr) anions and also ionic liquids based on 1-ethyl-3-methylimidazolium [emim]+ cation and alkyl-trifluoroborate ([RBF3]-, R=n-CmH2m+1 (m=1-5)) anions were discussed at the DFT(B3LYP)/6-311++G(d,p) level of theory. Then, the effect of chain length in anion on the nature and strength of interaction between cation and anion was investigated. Our results indicated that interaction energy values decrease with the increase in side chain size in anion. NBO and QTAIM results indicated that the interaction in these... 

Graphene quantum dots (GQDs) as a sort of carbon-based nanomaterials are applied in a multitude of exciting areas. They are effective fluorescent probe for many potential biological and medical applications. In comparison to conventional organic fluorescent probes (organic dyes), GQDs have substantial advantages, such as photostability, excellent solubility, low cytotoxicity and biocompatibility.
In this thesis, green fluorescent GQDs have been prepared via solvothermal method from graphite powder.Various analysis methods were utilized to characterization of the product. So, several experiments on GQDs in solution and in solid substrate at room temperature have been performed. The...