Sharif Digital Repository

In this report, a combination of in-situ chemical synthesis and electrolysis methods was applied for the preparation of zinc oxide/graphene quasi core-shell nanoparticles. Pure zinc oxide was also prepared using the same method at different temperatures. The degree of 100 ◦C was selected for synthesizing of ZnO-GO quasi core-shell (zinc oxide as a core and few layer of graphene oxide as a shell). The particle size was 15±2 nm in all samples. In both processes, oxygen was the main reason for the connection between the core and the shell. Unlike chemical process that has all kind of functions in electrolysis process, one kind of function was produced and confirmed by FTIR. XRD patterns also... 

The aim of conducting this research is to study, fabrication and photocatalytic application of electrospun ZnO-based composite nanofibers. One of the most important challenges is to apply photocatalyst under solar irradiation and improve its activity for pollutant degradation. ZnO is a wide band gap semiconductor, hence, it is not active under the visible light. In Iran, we have at least 300 sunny days in a year. Therefore, fabrication and application of photocatalytic material with activity under the sunlight which contains 47% of visible light is so vital in our country. Since CuO is a visible light active photocatalyst and its interface with ZnO forms a type I heterojunction, this... 

Aerobic oxidation plays important role in industrial processes and pollutant remediation. The catalysts accelerating oxidation reaction rate are included thermal (typical) catalysts such as Pt or Au on oxide supports and photocatalysts such as TiO2 or ZnO. Although well-studied Au/TiO2 system have been under deep
investigations but Au/ZnO system have less investigated because Au/ZnO has low activity relative to Au/ZnO. Gold nanoparticles supported on ZnO nanostructures were prepared through a simple chemical-thermal method and characterized by SEM, TEM, XRD, BET and photo luminescence (PL) spectroscopy. Effect of
annealing temperature on catalytic activity of these Au/ZnO... 

In this research we focus on study and fabrication of ZnO composite nanofibers by electrospinning method for photocatalytic application. The most important challenges in the field of photocatalyst are photocatalytic activity under the visible light and efficiency enhancement. ZnO is a wide band gap semiconductor and it is not active under the visible light. In Iran, we have more than 300 sunny days in a year. Therefore fabrication and application of photocatalytic material with activity under the sun light that contained 40% of visible light is so vital in our country. In the first part of this project, ZnO-CNT nanofibers were fabricated and carbon doped in the crystal lattice of the ZnO.... 

The World Health Organization's annual statistics show that 83% of wounds are caused by bacterial infections. Diabetic ulcers affect approximately 28 million people worldwide. The use of antibacterial dressings can help control infections. Recent studies have found that electrical stimulation can accelerate wound healing. However, there is still a need for interventions that speed up epithelial tissue formation. New dressings with zinc and silver particles that have electrical activity are being developed, but research on these methods is limited. Zinc oxide nanoparticles have been used as antibacterial agents due to their unique surface properties. This research aims to use these... 

Recently, some wound dressings have been designed that are expected to enhance the wound healing process and prevent blood bleeding and infection. Polymeric dressings have attracted attention due to their biocompatibility, biodegradability, lack of toxicity, and non-allergenic nature. There is widespread interest in using silk fibroin (SF) for this purpose because of its unique properties. Given these points, we have designed an injectable antioxidant hydrogel wound dressing based on SF and Polydopamine(PDA) modified ZnO nanoparticles. First, ZnO nanoparticles were doped with Cu and then modified with PDA (ZnCuO@PDA). XRD, FTIR, SEM, and TEM characterizations were carried out to confirm the... 

Zinc oxide is a wide band gap semiconductor material with wide applications as conductive oxides used in electro-optical devices. Thin films of doped zinc oxide (e.g. Al:ZnO, B:ZnO) are already used in thin-film solar cell technologies as electrodes. Chemical bath deposition (CBD) is a promising method for fabricating transparent and conductive ZnO layers at low temperatures (<100 °C) on nonconductive and temperature-sensitive substrates. Having a natural crystal habit, ZnO readily grows rod-like arrays when grown in an aqueous solution by CBD, posing challenges when attempting to deposit dense and conductive layers. The purpose of this study was to deposit dense and conductive zinc oxide... 

We demonstrated 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 (obtained from... 

Polycarbonate (PC) and polyethylene-terephthalate (PET) are important engineering thermoplastics. During last decades these polymers and their blends have been studied extensively due to their wide range of applications. Blends of PET and PC combine mechanical properties and chemical resistance together, which make applicable in various components such as automotive, electrical and of medical parts. It has been accepted that PET/PC immiscible blends are subjected to transesterification reactions during thermal processing, which produces PET-PC copolymer chains. In fact, scissioning and substitution of ester/carbonate functional groups of PC and PET at the interface, transforms the initial... 

The goal of this study is synthesis of nanocoating on basis of ZnO by Sol-Gel method and evaluation of their antibacterial and photocatalyst properties changes by different values of TiO2. For this purpose in both method of synthesis contents of TiO2 hase been changed from 0-25 molar percent. Dip coat method has been used for coating from sol with 1.4 mm/s withdrawal speed and 2 minute immersion time. After each step of coating samples has been dried at 150oC for 10 minute and for increasing thickness this process has been repeated 4 times. In first method zinc acetate dihydrate in 0.1 M final concentration and titanium tetraisopropoxide are sol precursors at in situ way of synthesis. In... 

For application as a biosensor electrode, Aligned Carbon Nanotubes (CNTs) were produced on Stainless Steel 304 substrate by optimizing the CVD method. For better performance, Zinc Oxide (ZnO) nanoparticles were coated on CNTs, using electrochemical deposition method at room temperature and process variables were optimized to acquire discrete particles with a narrow distribution. After that, Polyaniline, which is a conductive polymer, was electropolymerized on CNT/ZnO composite to further improve the electrocatalytic abilities of the electrode. The produced electrode was then used to detect glucose by Cyclic Voltammetry and Amperometry methods. This electrode shows a linear relationship... 

In the present work, one dimensional ZnO nanostructures were grown by seed-assisted hydrothermal method. Hydrothermal processing parameters were controlled to obtain ZnO nanorods with diameter lower than 120 nm. The products were characterized by FE-SEM, EDAX, XRD, PL, and ATR-FTIR analyses. ZnO nanoparticles were also synthesized via a simple solvothermal method and their photo peropeties were compared with onedimensional nanostructures. Thereafter dye-sensitized solar cells based on TiO2-ZnO double layer nanostructured film were fabricated. It was observed that DSSC efficiency increased with decreasing the thickness of the film. The highest efficiency of 2.41% was obtained  

Zinc oxide thin films due to special specification and properties have variable application in different industries. Recently because of wide application of zinc oxide doped SiO2 in optoelectronics and sensors, lots of investigation have been focus on it. Meanwhile due to the SiO2 hydrophilic properties, doping of ZnO with SiO2 can improve self-cleaning properties zinc oxide membrane.It this project zinc oxide and ZnO doped SiO2 thin films with different composition were made by sol-gel and dip-coating process used for coating of mentioned sol over the quartz surface(15*25 mm). At first point different sol with different components was mixed with each other to make composite films but due to... 

The aim of this research is to make a hierarchical zeolite catalyst as a basis for photocatalytic removal reactions of organic pollutants including dyes and drugs. The three main parts of this thesis deal with preparing the photocatalyst, performing the characterization test and investigating the reaction in different operating conditions. To prepare zeolite, first an organic molecule was synthesized to increase the diameter of the holes and it was used along with the rest of the precursors in the hydrothermal method. To increase the efficiency of photocatalytic reactions, the silver element was deposited on the ZnO / zeolite catalyst by photodeposition method and its characteristics were... 

Due to the increasing number of Advanced Oxidation Processes (AOPs) that are exploited to eliminate emerging and recalcitrant contaminants from water supplies, photocatalytic degradation of Reactive Blue 21 dye using Zinc Oxide nanoparticles is investigated in both a slurry phase and an immobilized photoreactor. The structural and optical properties of the prepared ZnO nanoparticles were examined by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and UV-Visible Diffuse Reflectance Spectroscopy (UV-vis DRS). The effects of photocatalyst concentration, calcination temperature, pH and UV lamps were optimized in the slurry phase photoreactor. It was shown that 250 ppm of ZnO that was... 

Aging of rubber compounds at high temperature and pressure acidic gas is a challenge for using them for a long time. Therefore, in this thesis aging of NBR/PVC compounds against H¬2S and CO2 has been investigated. The main method have been used is Full Factorial Design of Experiment. The parameters have been examined are content of zinc oxide, plasticizer RPO ASTM 290 and antioxidant 4010 NA. The content have been set in tow levels and effect of each have investigated in ambient and 120 degree of centigrad temperature. The results show that the effect of antioxidant 4010 NA on aging of compounds is negative and zinc oxide and plasticizer RPO ASTM 290 are positive  

Water-gas shift reaction (CO(g) + H2O(g) ↔ CO2(g) + H2(g)) is performed as the key step in the hydrogen and ammonia industrial plant. In this work, Fe/Cr/Cu high temperature water gas shift catalysts were synthesized by coprecipitation method, using sulfate precursors, in order to improve the catalytic performance and particular emphasis is placed on the catalytic activity affected by aging time, precipitating agent and ways of increasing the mechanical strength. Finally the prepared and industrial catalysts were compared when they were situated in the operating conditions (at 360oC and 2 bar) and were characterized by BET, XRD, TPR, TEM and crushing strength analysis. Catalysts being made... 

There are many archeological sites, historic building monuments and inscriptions in Iran and other countries in the world which have been damaged by environmental as well as biological causes. Lichens are one of the biological causes which, through their growth, bring about change and damage to the stones. Different methods, each of which has both advantages and disadvantages, have been used in order to deal with the problem. Since there are many historic buildings in our country which have been damaged by different biological causes including the lichens, doing a research on the topic seems to be quite significant and necessary. The Persepolis is among one of the most important historic... 

due to high mineralization rate of Zinc oxide، chemical and physical stability, non-toxicity and low price as the most promising photocatalysts studied, although its use is not too satisfactory. Because of the wide energy gap(3.2 ev) and for photocatalytic activity needs to UV light Unfortunately, the solar spectrum is made up only 5-7% of UV light, while 46-47% is the spectrum of visible light and infrared. Doped zinc oxide nanoparticles with metal and non-metallic atoms could increase the photocatalytic properties under visible light irradiation. In this research, nanoparticles of zinc oxide was doped by fluorine as Dopant. The results showed that photocatalytic activity of the modified... 

Water Gas Shift (WGS) reaction is an old reaction in which syngas is used for producing Hydrogen. At the present time, the major application of this reaction is in fuel cells, since the necessary Hydrogen for these cells is provided by this reaction.
The present study investigate the influence of different preparation methods on properties of Cu-ZnO/Al2O3 catalyst for water gas shift (WGS) reaction, which is now known as the Commercial catalyst for low temperature WGS, and its influence on performance of Cu-ZnO/Al2O3 catalyst to derive an optimal Cu-ZnO/Al2O3 catalyst for water gas shift (WGS) reaction. Cu-ZnO/Al2O3 catalysts was synthesized by CP, DP, DP-Ultra, IWI , CP-Urea, and...