Sharif Digital Repository

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... 

Improving the photocatalytic activity of titania nanoparticles and Cognition the mechanisms governing this property, has received more attention in the recent few years. One of the main strategies for improving the photocatalytic activity and modifying the bandgap structure of titania nanoparticles, is incorporation different metallic and nonmetallic ions in the titania lattice. In this study, 1%Fe, 1%Gd and 2%P (molar ratio) doped titania nanoparticles were successfully prepared by a modified sol-gel method in room temperature. The products were characterized with various spectroscopic and analytical techniques to determine their structural, morphological, physicochemical and... 

In this study, we synthesized ZSM-5 and doped ZSM-5 applying cations such as Zn(II) and Fe(II). Furthermore, we synthesized [Zn,Fe]-ZSM-5 using similar method for the first time. The final products were characterised by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. On the other hand, the hierarchical mesoporous Zn-ZSM-5 zeolite catalyst was prepared by alkali treatment by NaOH and Zn impregnation, and its application in the conversion of methanol to gasoline (MTG) process was studied. The modified zeolite samples after modification were also characterized by FT-IR and XRD methods. Zn impregnated mesoporous catalyst Zn-Alk-Z5 exhibited dramatic improvements in... 

Titania is one of the photocatalytic materials , but low quantum yield and relatively high band gap of TiO2 limited its applications.There are several ways to improve the photocatalytic properties of this material relied on narrowing the band gap,by doping TiO2 with other metals and oxides or increasing its specific surface area.In this work ,TiO2-SiO2-Ni coating have been made by sol-gel process and deposited on quartz substrate by using of dip-coating method .Effect of increasing Nickel content in nanocomposite and primary sol on crystalline structure,morphol ogy, photocatalytic properties and specific surface area have been investigated by means of X-Ray diffraction method, FT-IR, SEM,... 

In recent years, much attention has been focused on quantum dot films due to their high amount of surface area and their size-dependant band-gap tenability. However, high surface area results in increase in energy traps in case of insufficient surface passivation. In this research, PbS colloidal quantum dots were synthesized via hot injection route having the size of 3 nm approximately. Then cationic doping with Zn, Ca and Cd and ligand exchange of long oleic acid with short organic mercaptopionic acid were done. Excitonic peak of these dots and photoluminescence peak appeard in wavelengths of 930 and 1100 nm respectively. Optimum film thickness was also determined as 300 nm. Quantum dot... 

Improvement of semiconductors photocatalytic activity by different means has always been one of the challenges for researchers. Semiconductors doping for band-gap engineering and changing morphology to increase specific surface area and photocatalytic reaction sites are amongst these efforts. In this research simultaneous effect of these two parameters for three morphologies containing nanoparticle, nanowire and micro dandelion, simultaneously doped with carbon and nitrogen has been investigated. Final purpose of this thesis is to decrease the band-gap energy close to soft UV photon energies to make surface photodynamic therapy possible. Nanoparticle morphology with size distribution between... 

Li-ion batteries have been widely applied as power sources for portable electronic devices. Recently, Li-ion batteries are considered as the most promising energy storage technology for electric vehicle applications however, fundamental improvements are needed. TiO2 (B) is attractive candidate for anodes in rechargeable Li-ion batteries, due to their low cost, non-toxicity and favorable channel structure for fast lithium mobility. It is predicted that synthesis of doped nanostructure of this material, through reducing the diffusion pathway and formation of crystal defects, will increase the capacity of TiO2(B). In this investigation, Co and V doped TiO2(B) nanowires are synthesized by... 

In this thesis, we focus on studying and fabrication of doped titanium dioxide electrodes and their application in nanostructured dye sensitized solar cells (DSSCs). For this purpose, non-metallic nitrogen (N) and metallic neodymium (Nd) elements were selected. N-doped titanium dioxide nanoparticles were synthesized via solvothermal method and their structural and optoelectrical properties were investigated in comparison to undoped titanium dioxide synthesized by the same method. Based on the obtained results, doping of titanium dioxide by nitrogen resulted in shifting the Fermi level up-ward, increase in charge carriers density, shift of optical absorbance to higher wavelength, and decrease... 

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... 

In this study, different metal oxides were impregnated on the surface of ZSM-5 employed as photocatalysis for degradation of methylene blue dye used in the presence of ultraviolet light. The final products were characterized by powder X-ray diffraction (XRD) and fourier transform infrared (FT-IR) method. According to the proposed mechanism for the photocatalytic degradation of methylene blue based on these results, it was found that the reaction followed from the first-order mechanism. The results indicated that rate constant for pure ZSM-5 was 9.3〖 ₓ10〗^(-3) (min-1). Furthermore the impregnated ZSM-5 having 12% zinc oxide demonstrated the highest photocatalytic activity with rate constant... 

The main purpose of this research was simultaneous doping of carbon and nickel in the structure of barium strontium titanate, in order to investigate its dielectric and optical properties. Powders and films of BST, was synthesized by the sol-gel method in six different compositions: without any dopant, 0.04mol nickel dopant, 0.04mol nickel dopant accompanied by different amounts of carbon (0.01, 0.02, 0.03 and 0.04 mol). Suspensions were dip coated on alumina and quartz substrates. Structural features and chemical bonds, were studied through thermal analysis, XRD, FT-IR, FESEM and AFM. For electrical and optical properties, LCR-meter and UV-Vis were used. XRD and FESEM proved that nickel... 

Nowadays, one of the most important research goals is to develop intermediate-temperature solid oxide fuel cells (IT-SOFC) operated at 500–800 °C. However, the large cathode polarization resistance caused by the reduced temperature is a major barrier against such an urgent demand for commercialization. In this regard, it is necessary to select a proper material as a cathode working efficiently at reduced temperatures without losing its desired performance. Various mixed ionic electron conductors (MIECs), especially Ruddlesden–Popper-type oxides, are used to improve the cathode performance at intermediate temperatures. Among these layered oxides, Pr2NiO4 has been reported to possess the... 

The variety of 2D materials and their wide range of properties, as well as numerous methods to manipulate them, have made this class of materials among prominent candidates for the future of the energy industry. Among the means available to tailor nanomaterials performance for such applications, introducing dopants and the creation of heteroatom-doped structures are of great interest. In this study, mixtures of urea, boric acid, and graphene oxide, as cheap and available precursors, were used to synthesize C-doped h-BN nanosheets. After the implementation of TGA/DSC to select a suitable calcination temperature of 950 C°, the samples were successfully synthesized with relatively precise... 

With decreasing fresh water availability and growing demand for clean water, alternative water sources are used in many parts of the world. At the same time, the increasing environmental pollution with a variety of manmade chemicals with known or unknown effects on the aquatic wildlife and human health is an uncontested reality. These emerging pollutants include pharmaceuticals and personal care products, pesticides and hormones. Due to the high sensitivity of color pollutants and many concerns about this issue, in this study, by designing and optimizing a falling film reactor, the removal of Basic red 46 dye from water by advanced oxidation method is investigated. The photocatalytic...