Sharif Digital Repository

Inclusion of carbon nanotubes (CNTs) into the titanium dioxide coating on 1050 aluminium alloy was studied with the aim at enhancing the corrosion resistance of the surface. Composite coatings with various contents of CNTs were prepared via the sol-gel method and dip coating. XRD and FTIR phase and structural evaluations showed the presence of anatase phase in all thin films. Concomitant enhanced corrosion behaviour in the presence of CNTs was resulted from polarization potentiodynamic test. Band-gap evaluation was performed using absorbance spectra of coatings and showed considerable decrease of band-gap energy in the presence of CNTs. Photocatalytic properties and hydrophilicity of... 

The objective of this study was to model the extent of improvement in the degradability of phenol dyes by SnO2/Fe3O4 nanoparticles using a photocatalytic reactor. The effect of operative parameters including catalyst concentration, initial dye concentration, stirring intensity, and UV radiation intensity on the photocatalytic batch reactor during removal of phenol red was investigated. Fractional factorial design and response surface methodology were used to design the experiment layout. The SnO2/Fe3O4 nanoparticles were synthesized using the core-shell method. The results of x-ray diffraction and transmission electron microscopy showed the successful synthesis of these nanoparticles. The... 

ZnO was grown on mordenite zeolite, activated carbon and alumina substrates by a liquid deposition method. The photocatalytic activity of the synthesised samples was elucidated using the photodegradation of Acid Blue 92 (AB92) dyes as a test pollutant under UV light irradiation. Supports play a key role in AB92 photodegradation and significantly improve the photocatalytic activity of ZnO. Different supports form additional transport channels and provide an effective pathway for the charge carriers. The supports effectively construct porous structures with more active sites. Hence, the higher photocatalytic activity of supported catalysts is attributed to the large surface area and charge... 

Very recently, we fabricated (WO3)x-(TiO 2)1-x layers via micro-arc oxidation process under different applied voltages. Morphological and topographical studies, accomplished by SEM and AFM techniques, revealed that the pores size as well as the surface roughness increased with the voltage. Phase structure and chemical composition of the layers were also investigated by XRD and XPS and the results showed the grown layers consisted of titanium and tungsten oxides. It was found that WO3 dispersed in the TiO2 matrix and also doped into the TiO2 lattice. In addition, optical properties of the synthesized layers were studied employing a UV-vis spectrophotometer. Band gap energy of the layers was... 

Local photodegradation of graphene oxide sheets at the tip of ZnO nanorods was used to achieve semiconducting graphene nanomeshes. The chemically exfoliated graphene oxide sheets, with a thickness of ∼0.9 nm, were deposited on quartz substrates. Vertically aligned ZnO nanorod arrays with diameters of 140 nm and lengths of <1 μm were grown on a glass substrate by using a hydrothermal method. The graphene oxide sheets were physically attached to the tip of the ZnO nanorods by assembling the sheets on the nanorods. UV-assisted photodegradation of the graphene oxide sheets (with dimension of ∼5 × 5 μm) at a contact place with the ZnO nanorods resulted in graphene nanomeshes with a pore size of... 

Pure titania porous layers consisted of anatase and rutile phases, chemically and structurally suitable for catalytic applications, were grown via micro-arc oxidation (MAO). The effect of applied voltage, process time, and electrolyte concentration on surface structure, chemical composition, and especially photocatalytic activity of the layers was investigated. SEM and AFM studies revealed that pore size and surface roughness of the layers increased with the applied voltage, and the electrolyte concentration. Moreover, the photocatalytic performance of the layers synthesized at medium applied voltages was significantly higher than that of the layers produced at other voltages. About 90% of... 

A novel visible-light-driven Ag3VO4/Ag3PO4/Ag photocatalyst was successfully synthesized via an anion-exchange reaction and characterized by X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, UV-vis diffuse-reflectance spectroscopy and Fourier transform infrared spectroscopy. The photocatalytic activities of prepared catalysts were evaluated by degradation of acid blue 92 (AB92) aqueous solutions under visible light irradiation. The photocatalytic results indicated that the synthesized Ag3VO4/Ag3PO4/Ag hybrid displays a significantly enhanced activity in degradation of acid blue 92 under visible light compared with pure Ag3VO4. The improved... 

The main aim of the present study was to enhance the degradation capacity of Acid Blue 92 (AB92) by visible-light-active Ag3PO4 nanocomposites based on g-C3N4 and Multiwalled Carbon Nanotubes (MWCNTs). The nanocomposites were fabricated through a tunable in situ deposition method. The properties of the resulting samples were investigated by X-ray diffraction, scanning electron microscopy and Fourier transform infrared (FTIR) spectroscopy. The photocatalytic activity results revealed that the Ag3PO4/g-C3N4 heterojunction inorganic/organic composite exhibited an improvement in both efficiency and the rate of AB92 photodegradation in comparison with the others. The enhanced photocatalytic... 

Graphene-supported BiPO4/Ag/Ag3PO4 photocatalyst has been fabricated by simple hydrothermal and impregnation reaction. In BiPO4/Ag/Ag3PO4 based on Reduced Graphene Oxide (RGO), this network renders numerous pathways for rapid mass transport, strong adsorption and multireflection of incident light; meanwhile, the interface between BiPO4/Ag/Ag3PO4 and RGO increases the active sites and electron transfer rate. BiPO4/Ag/Ag3PO4 based on RGO noticeably exhibited high photocatalytic activity than that of BiPO4/Ag/Ag3PO4 and P25 under visible light irradiation for cationic dye (Rhodamine B), anionic dye (methyl orange) and 4-chlorophenol (4-CP) as a neutral pollutant, which are usually difficult to... 

Graphene oxide platelets synthesized by using a chemical exfoliation method were deposited on anatase TiO2 thin films. Postannealing of the graphene oxide/TiO2 thin films at 400 °C in air resulted in partial formation of a Ti-C bond between the platelets and their beneath thin film. By using atomic force microscopy and X-ray photoelectron spectroscopy analyses, UV-visible light-induced photocatalytic reduction of the graphene oxide platelets of the annealed graphene oxide/TiO2. thin films immersed in ethanol was studied for the different irradiation times. After 4 h of photocatalytic reduction, the vertical space between the platelets decreased from about 1.1 to less than 0.8 nm and the... 

The major purpose of this research is increasing the photocatalytic activity of TiO2 nanotube arrays by doping with sodium and carbon for using in water splitting as photoanode. The synthesized TiO2 nanotubes (TNA) were characterized using FESEM (Field Emission Scanning Electron Microscope), XRD (X-ray Diffraction), DRS (Diffraction Reflection Spectroscopy) and XPS test (X-ray Photoelectron Spectroscopy) analyses. The results of FTIR and XPS confirmed the presence of sodium and carbon in the lattice of TNA as dopants. Moreover, the DRS test showed the decrease in the band gap energy of TNA from 3.20 to ∼2.88 eV; uv-visible test exhibited extension in the absorption edge of pure TiO2... 

Au@TiO2-Graphene (GR) nanocomposite was prepared using photocatalytic reduction method. TiO2-GR nanocomposite was synthesized under UV irradiation of deaerated ethanolic suspension of TiO2. The nanocomposite was calcined at 400∘C followed by loading of highly dispersed Au nanoparticles throughout the deposition-precipitation method. The Au@TiO2/GR was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, diffuse reflectance spectroscopy, transmission electron microscope and the BET surface area measurements. It was found that Au-TiO2-GR and TiO2-GR nanoparticles have smaller crystalline size and higher surface area than pure TiO2. Presence of highly dispersed Au nanoparticles... 

Herein, a novel quaternary Ag3PO4/BiPO4@MIL-88B(Fe)@g-C3N4 (AB@MIL-88B(Fe)@g-CN) nanocomposite with a core@shell structure is successfully fabricated in two simple steps. The prepared samples are characterized via various techniques. The photocatalytic activity of the prepared samples is evaluated by the degradation of navy Acid Blue 92 (AB92) dye as an organic pollutant under visible light irradiation. Highly enhanced photocatalytic efficiency is observed for the quaternary AB@MIL-88B(Fe)@g-CN nanocomposite compared to that for the other samples. The experimental results indicate that the photocatalytic activity enhancement is mainly attributed to the strong visible light absorption and... 

Sol-gel technique was used to coat multiwall carbon nanotubes (MWCNTs) with anatase titania to increasing the surface area and improve the photocatalytic activity of TiO2. Room temperature ballistic conduct of MWCNT combined with semiconducting behavior of anatase brought about a photocatalytic improvement of ∼37 % with respect to the highest methyl orange decolorization flair. For characterization and photocatalytic efficiency determination, X-ray diffraction (XRD), field emission (FE) scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS) and ultraviolet visible (UV-vis) spectroscopy were rehearsed. Attachment of anatase... 

The main purpose of this research work is to investigate the effect of nickel as metal dopant on the morphology and photocatalytic activity of TiO2 nanotube arrays synthesized in the organic electrolyte by anodizing process containing sodium carbonate as an additive (TNAS). In order to characterize the synthesized nanotubes, various analyses such as FESEM, XRD, FTIR, XPS, DRS, and EIS were applied. The results of XPS and FTIR tests evaluate the participation of sodium (Na), nickel (Ni), and carbon (C) in the lattice of nanotubes as dopants. According to the DRS and UV-visible tests results, the band gap energy of TiO2 nanotube arrays decreases from 3.20 to ~ 2.64 eV as well as the absorption... 

Fast transfer of photoinduced electrons and subsequent slow electron-hole recombination in semiconductor heterostructures give rise to long-lived charge separation which is highly desirable for photocatalysis and photovoltaic applications. As a type II heterostructure, CdS/TiO2 nanocomposites extend the absorption edge of the light spectrum to the visible range and demonstrate effective charge separation, resulting in more efficient conversion of solar energy to chemical energy. This improvement in performance is partly explained by the fact that CdS/TiO2 is a type II semiconductor heterostructure and CdS has a smaller energy band gap than UV-active TiO2. Ultrafast transient absorption... 

Ternary novel BiOI@MIL-88A(Fe)@g-C3N4 nanocomposite with core@shell structure was successfully synthesized by hydrothermal method. fabricated photocatalysts were characterized and results confirmed the formation of MIL-88A(Fe)@g-C3N4 core@shell structure and subsequently BiOI decoration on the surface of MIL-88A(Fe)@g-C3N4. Photocatalytic performances of prepared samples were investigated for degradation of Acid Blue 92 (AB92), Rhodamine B (RhB) and phenol under visible irradiation. It is clearly demonstrated that the as-prepared ternary BiOI@MIL-88A(Fe)@g-C3N4 composites exhibits exceptional visible-light photocatalytic activities for cationic, anionic as well as neutral pollutant molecules... 

A new plasmonic Ag hybridized CuWO4/WO3 heterostructure was successfully synthesized via a ligand-assisted sol gel method. The as-prepared plasmonic nanohybrid was thoroughly characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectroscopy, photoluminescence (PL) spectrometry, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis and electrochemical impedance spectroscopy (EIS). Moreover, the photocatalytic activity was evaluated by photo-degradation of methylene blue (MB) under visible light irradiation. The results indicate that the as-prepared plasmonic Ag-CuWO4/WO3 nanohybrid (compared to pure... 

In this paper, three metal-organic frameworks (Materials of Institut Lavoisier: MILs-100 (Fe)) as porous nanomaterials were synthesized using FeCl3, Fe(NO3)3 and Fe2(SO4)3 and denoted as MIL-100-1, MIL-100-2 and MIL-100-3, respectively. The synthesized MILs-100 (Fe) were characterized by FTIR, SEM, TEM, XRD, UV–vis DRS and zeta potential. Basic Blue 41 (BB41) was used as a model dye to study the photocatalytic dye degradation ability of the synthesized metal organic frameworks. The results showed that the synthesized nanomaterials decolorized BB41. The decolorization kinetics followed first-order kinetic model. The rate constant was 0.0034, 0.0041, 0.0091 and 0.0289 (1/min) for 0.01, 0.02,... 

In this review, the importance of nanoparticles (NPs), with emphasis on their general and specific properties, especially the high surface-to-volume ratio (A/V), in many technological and industrial applications is studied. Some physical and chemical preparation methods for growing several metallic and binary alloy NP catalysts are reviewed. The growth and mechanism of catalytic reactions for synthesis of 1D nanostructures such as ZnO nanowires and multiwall carbon nanotubes (MWCNTs) are discussed. Gas-phase production with emphasis on dependence of catalytic activity and selectivity on size, shape and structure of NPs is also investigated. Application of NP catalysts in several...