Sharif Digital Repository

This study focused on the synthesis of TiO2-Zeolite nanocomposite through a sol-gel approach. The decrease in the size of the nanocomposite is considered a primary parameter to improve photocatalytic activity. In this regard, fabricated samples were exposed to laser irradiation (532 nm) for four different time intervals in order to investigate the size variation of the nanocomposite. FTIR, UV-Vis, XRD, DLS, SEM and EDX analyses were applied to characterize and determine the size of the products. An optimized nanocomposite sample, in term of the particle size, was used for photodegradation of 2,4-D herbicide from aqueous solution. Photodegradation was carried out under UV irradiation (12 W)... 

TiO 2 -rGO nanocomposite coatings were obtained by electrophoretic deposition (EPD) technique of TiO 2 nanoparticles and graphene oxide (GO) on stainless steel substrate. First, GO particles were synthesized using a modified Hummers' method. GO was reduced electrochemically to form a coating in the presence of nano-sized TiO 2 particles. The influences of different parameters such as GO concentration, coupling co-electro-deposition parameters (electrophoretic duration and voltage) on thickness, surface morphology and, corrosion behavior of the as-synthesized TiO 2 -rGO nanocomposite coatings were systematically surveyed. The morphology and microstructure were investigated by field emission... 

In this study, biocompatible ceramic layers containing TiO2 and hydroxyapatite (HA) nanoparticles (TiO2/HA) were deposited on pure commercial titanium (Grade 2) by using plasma electrolytic oxidation and AC power supply. The coating process was carried out in five different solutions for various times at a current density of 500 mA cm−2. To achieve the optimum conditions for thickness and microstructure, the coating process was conducted in solutions with a 3 g L−1 concentration of HA nanoparticles. FESEM, XRD, and FTIR results showed that HA nanoparticles were successfully incorporated into the pores of the layer. Furthermore, the corrosion behavior of the coating layers in the simulated... 

As a low-cost method, hydrophilic SiO2 nanoparticles (NPs) and fluid catalytic cracking (FCC) coarse particles were used as assistant materials to improve the fluidity of Al2O3 and TiO2 hard-to-fluidize nanopowders. To decrease the strong electrostatic forces between the hydrophilic nanopowders, prepared samples were fluidized in the presence of methanol vapor. Results revealed that the amount of SiO2 NPs, increased from 5 to 50 wt. %, has a beneficial effect on the fluidization quality of the binary (hard-to-fluidize NPs + SiO2) and ternary (hard-to-fluidize NPs + SiO2 + FCC) mixtures. However, the amount of FCC particles when it varied from 15 to 30 wt. % in the ternary mixtures should... 

Zirconium based metal-organic frameworks (Zr-MOFs) are promising candidates for photocatalytic wastewater treatment due to their excellent properties such as high chemical and thermal stability and high photodegradation ability. Herein, we report a novel porous TiO2/ZrO2 photocatalyst derived from UiO-66 and Titania hybrids. UiO-66 nanoparticles was synthesized through solvothermal method and utilized as catalyst support to grow TiO2 particles on its surface. The prepared Titania/MOF nanocomposite was calcined to obtain porous TiO2/ZrO2 photocatalyst for degradation of organic pollutants from colored wastewater under LED visible light. The prepared materials were fully characterized with... 

Recently, membrane fouling has been one of the most important issues in the field of membrane technology. In this regard, TiO2 nanoparticles blended with polymeric membranes have shown to improve fouling performance. In this study, a new PVDF/PAN/TiO2 ultrafiltration blend membrane was prepared via phase inversion by dispersing TiO2 nanoparticles in the PVDF/PAN casting solutions. The effect of different concentrations of TiO2 on the characteristics of membranes (i.e., morphology, hydrophilicity, permeation performance, and antifouling properties) was investigated. Results of scanning electron microscopy analysis showed the finger-like pores and macrovoids decrease due to the presence of... 

Production of Al1050/TiO 2 -graphite hybrid nanocomposite via friction stir processing (FSP) was studied. The effect of graphite-to-TiO 2 volume fraction ratio (Gr/TiO 2 ), at a constant rotational speed (ω) and three levels of tool traverse speed (ν), on the microstructural evolution and mechanical properties of the nanocomposites was investigated. While TiO 2 is supposed to enhance the strength and hardness, graphite is believed to improve the tribological behavior. Furthermore, formation of intermetallic compounds (IMCs) through the solid-state reactions between the reinforcements and aluminum matrix may also promote the mechanical properties. To assess these assumptions, longitudinal and... 

H2O-assisted atmospheric pressure chemical vapor synthesis is a modern economical process for the gas-phase synthesis of TiO2 nanoparticles. In the present work, the influence of synthesis temperatures (100-800 °C) on the phase structure, nanoparticle size, morphology, and agglomeration is investigated by transmission electron microscopy, selected area electron diffraction, X-ray diffraction, thermogravimetry, and differential thermal analysis. Down to 400 °C, crystalline TiO2 nanoparticles are synthesized and at 200 °C amorphous nanoparticles are formed. Therefore, a decrease in minimum synthesis temperature by more than 500 °C is achieved. In addition, the paper investigates the hypothesis... 

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... 

Herein, we report the impact of light scattering mechanism on photovoltaic and photoelectrochemical performance of dye-sensitized solar cell (DSC) devices composed of TiO2 nanoparticles and hollow cubes. DSCs are designed by two different light scattering modes (i.e., mode I in form of single layer electrode containing nanoparticles and hollow cubes and mode II in the form of double layer electrode comprising active and scattering layers made of nanoparticles and mixtures of nanoparticles and hollow cubes, respectively). The synthesized anatase-TiO2 hollow cubes (200–400 nm) and nanoparticles (15–30 nm) are employed to enhance the optical length and light harvesting of photoanodes,... 

Herein, enhancement of dye-sensitized solar cell (DSC) performance is reported by combining the merits of the dye loading of TiO2 nanoparticles and light scattering, straight carrier transport path, and efficient electron collection efficiency of TiO2 cubes. We fabricate DSC devices with various arrangement styles and compositions of the electrodes in the forms of monolayer and double layer films. For this purpose, the solvothermal synthesized TiO2 cubic particles (100-600 nm) are employed as the scattering layer, whereas TiO2 nanoparticles (15-30 nm) synthesized via a combination of solvothermal and sol-gel routes are used as the active layer of devices. We improve the photovoltaic... 

The influence of particle size and surface modification on sonocatalytic activity of TiO2 nanoparticles was investigated by measuring the degradation efficiency of methyl orange (MO) as a model pollutant. Crystalline TiO2 nanoparticles with different particles and aggregate size were prepared through solution-phase method with varying synthesis temperatures. Coating with polyvinyl alcohol was performed to enhance colloidal stability of the particles over a wide range of pH values (1.5–7.5). Characterization was carried out using X-ray diffraction, high-resolution transmission electron microscopy, dynamic light scattering, and Fourier-transformed infrared techniques. It was found that... 

Friction stir processing (FSP) is a solid state route with a capacity of preparing fine grained nanocomposites from metal sheets. In this work, we employed this process to finely distribute TiO2 nanoparticles throughout an Al-Mg alloy, aiming to enhance mechanical properties. Titanium dioxide particles (30 nm) were preplaced into grooves machined in the middle of the aluminium alloy sheet and multipass FSP was afforded. This process refined the grain structure of the aluminium alloy, distributed the hard nanoparticles in the matrix and promoted solid state chemical reactions at the interfaces of the metal/ceramic particles. Detailed optical and electron microscopic studies showed that the... 

Colloidal stability of dextran (Dex) and Dex/poly ethylene glycol (PEG) coated TiO2 nanoparticles (NPs) were investigated. The particles were successfully synthesized by a hydrothermal assisted sol-gel technique. The results of Ultraviolet-visible (UV-vis) spectrophotometry showed that Dex and PEG additions during hydrothermal process (HTP) led to the formation of long-term (more than 60 days) stable colloids, while the addition of dispersants after HTP did not have a significant impact on the colloidal stability of NPs. X-ray diffraction (XRD) and selected area electron diffraction (SAED) analyses proved that PEG and/or Dex coated NPs had less crystallinity than the plain TiO2. Fourier... 

A new facile strategy for fabrication of high surface area electrode in the form of mixtures of coated carbon nanotubes (CNTs) and TiO2 nanoparticles with various weight ratios is reported. The so-called polymeric gel process was used to deposit thick film containing uniform distribution of TiO2 nanoparticles and coated CNTs with high porosity by dip coating for dye-sensitized solar cells (DSSCs) applications. Based on simultaneous differential thermal analysis, the minimum annealing temperature to obtain inorganic- and organic-free films was determined at 500°C. X-ray diffraction analysis revealed that deposited films were composed of primary nanoparticles with crystallite size in the range... 

Hydrolysis of titanium isopropoxide alcoholic solution has been used to prepare the crystallized TiO2 nanoparticles at low temperature. Concentration ratio was used to control the pathway of sol-gel process and change the physical characteristics of TiO2 nanopowders. The crystallinity, morphology and size of aged TiO2 nanopowders were studied by X-ray diffraction and Scanning Electron Microscopy (SEM). FTIR and, Thermo-Gravimetric (TG) analysis were used to identify the functional groups and thermal behavior of prepared samples. Experimental results have shown that high crystalline TiO2 nanomaterial with anatase polymorph can be obtained at room temperature. It has been found that the... 

A modified carbon paste electrode was prepared by incorporating the TiO2 nanoparticles in the carbon paste matrix. The electrochemical behavior of gallic acid (GA) is investigated on the surface of the electrode using cyclic voltammetry and differential pulse voltammetry. The surface morphology of the prepared electrode was characterized using the scanning electron microscopy. The results indicate that the electrochemical response of GA is improved significantly at the modified electrode compared with the unmodified electrode. Furthermore, the capabilities of electron transfer on these two electrodes were also investigated by electrochemical impedance spectroscopy. Under the optimized... 

Reduced graphene oxide (RGO) was used to improve the hydrogen sensing properties of Pd and Pt-decorated TiO2 nanoparticles by facile production routes. The TiO2 nanoparticles were synthesized by sol-gel method and coupled on GO sheets via a photoreduction process. The Pd or Pt nanoparticles were decorated on the TiO2/RGO hybrid structures by chemical reduction. X-ray photoelectron spectroscopy demonstrated that GO reduction is done by the TiO2 nanoparticles and Ti-C bonds are formed between the TiO2 and the RGO sheets as well. Gas sensing was studied with different concentrations of hydrogen ranging from 100 to 10,000 ppm at various temperatures. High sensitivity (92%) and fast response time... 

We report a simple and inexpensive synthesis route of TiO2 nanoparticles using electrical arc discharge between titanium electrodes in oxygen bubbled deionized (DI) water followed by heat treatment. The resulting nanoparticles were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD patterns demonstrate formation of TiO2 phase in oxygen bubbled water after heat treatment and dominance of rutile to anatase phase. The size and morphology of TiO2 nanoparticles were studied using different arc currents as a crucial parameter in properties of final... 

A carbon paste electrode (CPE) chemically modified with TiO2 nanoparticles and quinizarine (QZ) was used as a selective electrochemical sensor for the simultaneous determination of minor amounts of d-penicillamine (D-PA) and tryptophan (Trp). This modified electrode showed very efficient electrocatalytic activity for anodic oxidation of both d-PA and Trp. Substantial decreases of anodic overpotentials for both compounds made this analysis possible. Results of square wave voltammetry (SWV) using this modified electrode showed two well-resolved anodic waves for the oxidation of d-PA and Trp, which makes the simultaneous determination of both compounds possible. The peak potential for the...