Sharif Digital Repository

Core-shell structures of Ag@Pt nanoparticles (NPs) dispersed on Carbon Vulcan XC-72, Multiwalled carbon nanotube and reduced graphene oxide (rGO) support containing different Ag:Pt mass ratios and applied to the oxygen reduction reaction (ORR) in a proton exchange membrane fuel cell (PEMFC) were synthesized by the ultrasonic and reduction treatment method. The morphology of as-prepared catalysts characterized by the high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and induced coupled plasma atomic emission spectroscopy (ICP-OES). The ORR activities and stabilities of catalysts were studied through electrochemical measurements utilizing the Cyclic Voltammetry... 

The aim of this study was to investigate the rate of increase in temperature of a phantom equivalent to body tissue by different groups of magnetic iron nanoparticles in the external magnetic field to kill cancer cells based on the hyperthermia method. To achieve this goal, three groups of dextran magnetic nanoparticles with different properties and reduced iron oxide-graphene oxide magnetic nanoparticles by M-rGO supercritical synthesis method were used. After XRD, FTIR, SEM, FESEM, VSM, TEM characterization tests, these materials were placed in a phantom made of agarose gel and with the same properties, in a magnetic field with fixed characteristics for all groups and during the process of... 

In this work, a new catalyst based on gold nanoparticles immobilized on magnetic GO (graphene oxide) has been introduced. A new ligand based on pyridine has been used to the functionalization of GO to design robust heterogeneous catalyst for reduction in a short time using a low amount of the catalyst. The prepared catalyst was employed in the synthesis of aromatic amines using various types of nitroarnes in water. This catalyst is readily prepared from available starting materials and also is a reusable catalyst having very good stability to air and moisture. The proposed procedure applied here can conduct the reactions under milder reactions. Finally, due to total removal of the... 

Although much progress has been made in eliminating, conserving, and reducing migration and emissions of radioactive materials, the risk of radioactive material release into the environment is still one of the most important hazards in the use of nuclear energy. In this study, graphene compounds have been used as adsorbents for the removal of radioactive materials due to their high level, cost-effectiveness and simplicity of the synthesis process of various composites. In this regard, the removal of strontium and cobalt by graphene compounds has been investigated. Magnetite nanoparticles were anchored on the surface of graphene by sol-gel method and adsorption in batch mode was investigated.... 

Supercapacitors are safe and environmentally friendly energy storage devices that have been considered for their diverse applications. One of the most important factors that control supercapacitors' capacity is the electrode material's structure and properties. Adding heteroatoms or composite materials synthesis is one way to improve electrode performance. In this study, a facile, fast, and economical hydrothermal method was used to synthesize N doped, P doped or N/P co-doped 3D reduced graphene oxide (rGO) for high-performance supercapacitor application. Nitrogen and phosphorus elements were replaced by carbon atoms simultaneously during the graphene oxide hydrothermal reduction procedure.... 

The reaction of oxygen evolution, in other words, the process of water oxidation in the presence of heterogeneous photocatalysts such as g-C3N4, Co/g-C3N4 /rGO, Ni/g-C3N4/rGO, CoNi/g-C3N4 / rGO, Co2Ni1/g-C3N4/rGO, and Co1Ni2 /g-C3N4 /rGO were studied. The characterization of these nanocatalysts was done by XRD, SEM, FT-IR, BET, DRS, CHN, and TGA techniques. Thermogravimetric analysis (TGA) was used to check the thermal stability of these nanocatalysts. The FT-IR spectroscopy was used to identify the functional groups in graphitic carbon nitride and to confirm g-C3N4 synthesis. According to BET results, the pore sizes were determined which were at the nano and macro scale. It was found that... 

TiO2 and TiO2-Graphene have been synthesized by hydrothermal method. Their physical, chemical and morphological properties have been investigated using XPS, XRD, FTIR, TEM, EDX, UV-Vis and AFM analyses. Moreover, photocatalytic efficiency of prepared materials has been examined using degradation of methylene blue. AFM image exhibited that monolayer GO with thickness of 10 nm was synthesized using modified Hummer’s method. FTIR analysis represented main characteristic peak of oxygen bond on the surface of GO, whereas for TiO2-Graphene most of oxygen functionalities on the surface were removed partially or completely. Photocatalytic degradation of MB proved this extension of light absorption.... 

In this research, an attempt was made to increase the efficiency and effectiveness of the targeted and controlled release systems of the anticancer drug (doxorubicin) by using inorganic and organic compounds as well as inorganic-organic hybrids. For this purpose, a whole class of aluminum fumarate metal-organic frameworks-based and reduced-graphene oxide nanocarriers were synthesized and using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), scanning electron microscope (FESEM) and atomic force microscope (AFM) analysis were characterized, and their nano-composites based on organotin-complexes with the approach of achieving a stable drug delivery system,... 

Myocardial Infarction occurs due to sudden blockage in a coronary artery and causes necrosis of myocardial tissue. Since myocardium is unable to self-regenerate, cardiac tissue engineering has become a promising therapeutic approach for MI treatment by restoring heart function via combination of cells, biomaterials and signaling factors. For this purpose, myocardial extracellular matrix (ECM) is an attractive biomaterial providing better biomimetic for cultured cells. In this project, we synthesized an in situ forming hydrogel derived from myocardial ECM and for improving mechanical and electrical properties of ECM hydrogel we added oxidized alginate (OA) with 5% oxidation degree and APTMS... 

In recent years, graphene-based materials have received much attention due to their prominent physicochemical properties such as high specific surface area, high mechanical strength and rich surface functional groups. In addition to these properties, low cost and environmental safety make graphene-based materials a green catalyst for many catalytic processes, including oxidative desulfurization. Tin oxide is a substance with strong acidic sites. Recent studies have shown that the oxidative desulfurization process using tin oxide nanoparticles is a new method for producing cleaner diesel fuels. In this study, rGO based tin oxide nanocatalyst was synthesized. To synthesize this catalyst,... 

The air cathode of li-air batteries plays a pivotal role in the overall performance of Li-air batteries. Graphene-based cathodes have been investigated as cathode catalysts for lithium-air batteries due to their extraordinary potential for accelerating and facilitating oxygen reduction reaction (ORR).In this study graphene oxide have been synthesized via modified Hummers’ method. Consequently, the as obtained graphene oxide have been reduced using chemical, electrochemical, and hydrothermal methods. Results of elechtrochemical evaluations demonstrate that the graphene oxide reduced via hydrothermal method possesses the most positive ORR onset potential (+0.55V vs SHE) among the other samples... 

The main purpose of this research was functionalizing graphene, in order to achieve higher hydrophobicity, and producing nanocomposite of functionalized graphene and titanium dioxide by hydrothermal method, and sequently invastigation on photocatalytic properties of the powders and corrosion properties of EPD coated samples. Graphene oxide was synthesized by improved Hummers method and reduced and sequently was functionalized through the chemical process with hydrazine and octadecylamine respectively. Then the nanocomposite of functionalized graphene-titania was synthesized by use of titanium isopropoxide precursor and its photocatalytic properties were measured. The analysis of the... 

In this project, graphene oxide was produced by chemical method (modified hummers method) because of simplicity and reproductiblity in the manufacuring process. Zinc nanoparticles were produced from pure zinc anode in the graphene oxide solution (anodic dissolution). Nanocomposite coating of reduced graphene oxide – zinc was created by electrochemical reduction with voltage pulse. Optimization of corrosion current density of the coating was done by design of experiments software (central composite design). To achieve this goal, several parameters such as cycles of zinc dissolution, frequency, duty cycle, total time of coating and applied voltage were examined. Using analysis of variance... 

Fabrication of porous hybrid coatings, specially in combination with carbon compounds, can improve the electrochemical behavior of the coating. In this study, graphene oxide (GO) was first synthesized by tour method. After examining different methods to create a porous coating, the electrochemical coating method for simultaneous deposition of GO and nickel on the copper substrate was selected. CTAB was used to form nanometer porosity in the coating structure. In order to investigate the effect of GO on the properties of the deposited coating, two porous coatings of nickel (Ni) and nickel reduced-graphene oxide (Ni-rGO) were investigated by different analyzes. These analyzes include FESEM... 

This research aimed at production of Cu-rGO via the combination of Molecular-Level-Mixing (MLM) method and powder metallurgy route (PM). First, Cu-GO composite powder was produced via MLM method. Subsequently, the resultant powder was mixed with electrolytic copper powder.Synthesis process included adjustment of the solution containing copper sulfate and 2Na.EDTA using NaOH solution. In the next step, GO suspension was added to the aforementioned solution. Finally, reduction of copper powder and formation of nanocomposite powder completed via the addition of Sodium Borohydrate. Nanocomposite powder was washed and dried in vacuum oven in 70˚C. GO reduction process took place using a tube... 

In the first part, a novel electrochemical sensor based on nanocellulose-carbon nanoparticles (NC–CNPs) nanocomposite film modified glassy carbon electrode (GCE) is developed for the analysis of metoclopramide (MCP). The electrochemical behavior of MCP was investigated on the surface of the modified electrode using cyclic voltammetry (CV). Characterization of the surface morphology and properties of NC/CNPs was carried out by scanning electron microscopy (SEM), atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS). Effective experimental variables, such as scan rate, pH of the supporting electrolyte, drop size of the casted modifier suspension and accumulation... 

In the first work, a stable composite film of silver nanoparticles decorated on reduced graphene oxide is easily prepared. The surface morphology of the modified electrode is characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The electrochemical behavior of TNZ on the surface of the modified electrode is investigated by using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The prepared modified electrode acts as a highly sensitive platform for the voltammetric determination of tinidazole (TNZ). Voltammetric investigations demonstrated that, in comparison to the glassy carbon electrode individually coated with... 

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... 

In the present study, TiO2-reduced graphene oxide (T-RGO) nanocomposites were synthesized via various in-situ and ex-situ methods, then their photovoltaic performance was examined as photoanode and mesoporous layers in dye-sensitized Solar Cells (DSSCs) and perovskite Solar Cells (PSCs), respectively. Graphene oxide (GO) was prepared using Hummer’s method with some modifications. Both thermal and hydrothermal processes were used to reduce GO. Structural and optical characterization was analytically demonstrated by subjecting of the obtained materials by several techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, thermogravimetric analysis (TGA),... 

Heat pipes are useful devices in heat transfer, renewable energies and cooling systems in particular. According to various application of this systems in different industries, performance improvement of this devices has gained much importance. Working fluid is one of the effective factors on pulsating heat pipes. Since heat transfer in PHPs is natural convection and two-phase, specific heat and thermal conductivity of working fluid have an important role in the performance of pulsating heat pipes. In the present study, the effect of using nano-encapsulated PCM along with reduced graphene oxid (RGO) dispersed in water and their mixture as working fluid has on the performance of PHPs has been...