Sharif Digital Repository

CuO flower-like microcrystals, prepared by a facile template-free thermal method, showed incredible photocatalytic activity towards degradation of Acid Blue 92 (AB92), an organic wastewater, Escherichia coli and Staphylococcus aureus pathogenic bacteria under visible light. The products were well characterised by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscope (SEM), Fourier transform infrared (FTIR), photoluminescence spectroscopy (PL) and diffuse reflectance spectra (DRS) analysis methods. The XRD pattern of the products well confirmed the formation of copper oxide crystalline phase without any other impurities. The results of the photocatalytic... 

In this study, MoS2/reduced graphene oxide (rGO) was used as a cocatalyst to synthesize very highly efficient Cu2O/MoS2/rGO for cooperative catalytic applications. The resulting nanocomposite was characterized by various analytical techniques and applied for catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol and photocatalytic degradation of Acid blue 92. Cu2O/MoS2/rGO composite presents superior performance to pure Cu2O particles in both catalytic and photocatalytic reactions. This excellent activity demonstrates synergistic effect of MoS2/rGO as a cocatalyst in the nanocomposite. The role of the active sites in the reduction of 4-NP and degradation of dye was discussed and... 

The main aim of this research is to improve the photocatalytic activity of TiO2 nanotubes by co-doping with copper and sodium for application in the water splitting process as a photoanode. The doping was performed simultaneously to the anodizing process through a single-step treatment. The synthesized TiO2 nanotube array (TNA) was characterized by applying FESEM (Field Emission Scanning Electron Microscopy), XRD (X-ray Diffraction), DRS (Diffraction Reflection Spectroscopy) and XPS (X-ray Photoelectron Spectroscopy) analyses. The results of XPS analysis proved the presence of copper with valence (2+) and carbon and sodium with valence (1+). Moreover, DRS tests showed a reduction in the band... 

Visible light-active BiOCl/BiVO4/mordenite and Ag/BiOCl/BiVO4 nanocomposite with a p–n heterojunction structure were prepared. Mordenite nanocrystals were synthesised using the hydrothermal method. Deposition and reduction methods were utilised to modify the Zeolite surface. The photocatalytic activities of the heterojunctions were investigated by scanning the change of Acid blue 92 (AB92) concentration under visible irradiation. The nanocomposites demonstrated improved efficiency for dye photodegradation. The activities are due to strong oxidative ability and efficient charge separation and transfer through the BiOCl/BiVO4 p–n junction. The photogenerated electron-holes react with species... 

Branched hierarchical zinc oxide nanowires (BH-ZnO NWs) were fabricated successfully by a facile and rapid synthesis using two-step growth process. Initially, ZnO NWs have been prepared by anodizing zinc foil at room temperature and followed by annealing treatment. Then, the BH- ZnO NWs were grown on the ZnO NWs by a solution based method at very low temperature (31 oC). The BH- ZnO NWs with different aspect ratio were obtained by varying reaction time (0.5, 2, 5, 10 h). Photocatalytic activity of the samples was studied under both UV and visible light. The results indicated that the optimized BH-ZnO NWs (5 h) as a photocatalyst exhibited the highest photoactivity with about 3 times higher... 

TiO2 has a high bandgap energy with light absorption in the ultraviolet region making it non-efficient under visible-light. The purpose of the present work is to modify the properties of TiO2 by adding carbon and copper to its structure, in order to acquire an active nanostructure for photocatalytic oxidative desulfurization of model liquid fuel under visible light irradiation. In this regard, carbon doped TiO2 was first synthesized by a hydrothermal method, then Cu (II) were impregnated on carbon doped TiO2. The resulting photocatalysts were characterized by techniques such as XRD, N2 physisorption, SEM, TEM, DRS, EDX, PL, and FTIR. The effects of parameters including calcination... 

A conic body packed bed reactor, internally irradiated with a UV-C lamp and equipped with circulating upflow stream was employed to investigate the decomposition of a widely used azo dye, direct red 16, in water. The synthesized nanostructure TiO 2 photocatalyst particles were immobilized on the surface of transparent Raschig ring packings. Solutions with initial concentration of 30 mg L -1 of dye, within the range of typical concentration in textile waste waters, were treated under the mild operating conditions of natural pH of 6.75 and temperature of 25 °C. Investigations on the active species showed that hydroxyl radicals play the major role in the process, providing a perfect degradation... 

(ZnO)1-x(CdO)x nanofibers were fabricated via electrospinning of polymer precursor by subsequent annealing in air. Field emission scanning electron microscopy (FESEM) showed the smooth and beadless nanofibers and X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) showed the ZnO hexagonal and the CdO cubic structure. Diffuse reflectance spectroscopy (DRS) showed the band gap energy reduction by increasing the amount of CdO in (ZnO)1-x(CdO)x nanofibers that resulted in the photocatalytic activity under the visible light for dye degradation. Under the UV light CdO acted as both electron and hole sink in the (ZnO) 1-x(CdO)x nanofibers and a possible photocatalytic activity... 

Novel ZnO-carbon and ZnO nanofibers were fabricated by electrospinning of polymer precursor followed by subsequent annealing in nitrogen and air, respectively. Field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) indicated the smooth and beadless nanofibers with wurtzite crystal structure. X-ray photoelectron spectroscopy (XPS) showed the presence of oxygen vacancies (VO) and chemisorbed O2 on the surface of the samples. Band gap narrowing of the ZnO-carbon nanofibers in comparison to ZnO were measured by diffuse reflectance spectroscopy (DRS). Photo-degradation of azo dye under the UV and visible light was evaluated and ZnO-carbon showed an enhancement in... 

TiO2-graphene (TiO2-GR) nanocomposites were synthesized using photocatalytic reduction method. TiO2-GR nanocomposites were thereafter doped with noble metals (Pt and Pd) by chemical reduction of the corresponding cations. The samples were characterized by different techniques. The addition of GR to TiO2 decreases the crystalline size of TiO2 due to the homogeneous dispersion of the TiO2 nanoparticles on GR sheets and prevention of coagulation of TiO2 nanoparticles during synthesis process. In addition, the surface area of TiO2 was increased by addition of GR and deposition of noble metals which helps to prevent agglomeration of graphene sheets and TiO 2 nanoparticles. Red shifts to the... 

We have studied systematically photocatalytic properties of the vertically aligned ZnO@CdS core-shell nanorods where the features were grown through a multistep procedure including sol-gel for the formation of ZnO seed layer, hydrothermal process to grow ZnO nanorods, and successive ion layer adsorption and reaction (SILAR) process to deposit CdS nanoshells onto the ZnO nanorods. Formation of the ZnO seed layer and vertically aligned ZnO nanorods (d ∼ 40 nm) with a hexagonal cross-section was confirmed by AFM and SEM imaging. Successful capping of ZnO nanorods with homogeneous CdS nanocrystallites (∼5 nm) was ascertained by HRTEM diffraction and imaging. Optical properties of the samples... 

This article investigates phenol removal from an aqueous solution by using enzymatic and photocatalytic methods and the efficiency of these methods has been compared. In enzymatic and photocatalytic methods, Coprinus cinereus, peroxidase enzyme and commercial TiO2 powders (Degussa P-25) in aqueous suspension were used, respectively, in ambient temperature. The effects of different operating parameters such as duration of process, catalyst dosage or enzyme concentration, pH of the solution, initial phenol concentration and H2O2 concentration on both processes were examined. In enzymatic method, efficiency of degradation reached 100% within 5min, while in the photocatalytic method, the... 

In this study, TiO 2-SiO 2 nanocomposite films with different amounts of SiO 2 were prepared by sol-gel process and were coated onto stainless steel 316L. The effect of addition of various amount of SiO 2 in the precursor solution on the photocatalysis, photo-generated hydrophilicity and self-cleaning property of TiO 2 thin films was investigated by X-ray diffraction, Fourier transform infrared spectroscopy, water contact angle measurements and UV spectroscopy. In the tested ranges of SiO 2 content and sintering temperature, the highest photocatalytic activity and self-cleaning property were observed in the 15 mol% SiO 2 sample sintered at 750 °C. Addition of less than 30 mol% SiO 2 had a... 

Graphene-tungsten oxide composite thin films with sheetlike surface morphology were fabricated and applied in photoinactivation of viruses under visible light irradiation. Using X-ray photoelectron spectroscopy, it was found that the chemically exfoliated graphene oxide sheets incorporated in the tungsten oxide film reduced through a visible light photocatalytic reduction. In addition, annealing the films at 450 °C in air resulted in formation of W-C and W-O-C bonds to obtain graphene-tungsten oxide composite films. The composite films fabricated by this method showed an excellent visible light photocatalytic performance in photoinactivation of bacteriophage MS2 viruses, as compared to... 

Zeolite-based Ag/AgBr and Ag/AgBr/TiO 2 photocatalysts were prepared by sol-gel and deposition methods and were characterized. Their photocatalytic activities were evaluated by inactivation of Escherichia (E.) coli and the photodegradation of Acid Blue 92 and potassium permanganate. The composites containing Ag/AgBr showed the antibacterial activity in the dark by releasing Ag ions into the medium. The results for inactivation of E. coli indicated that Ag/AgBr/TiO 2 modified photocatalyst had better antibacterial activity than Ag/AgBr/zeolite, while zeolite and TiO 2/zeolite did not show any antibacterial activity under visible light and dark conditions. Photodecolarization rate was affected... 

Using a combined hydrothermal and sol-gel route, TiO 2 -capped ZnO nanoparticles with an average size of 60 nm were prepared. The titania shell was amorphous with a thickness of ∼10 nm. Formation of Zn 2TiO 4 phase at higher calcination temperature was noticed. Effects of Ti/Zn molar ratio and coating time on the thickness of TiO 2 shell and the photoactivity of the particles for decolorization of Methylene Blue (MB) under UV lamp irradiation (3 mW/cm 2) were investigated. The nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, fourier-transform infrared spectrometry (FTIR), diffuse reflectance spectroscopy (DLS), and atomic absorption spectroscopy.... 

Various morphologies of CuO/Cu(OH)2 nanostructures with different adsorbed -OH contents were synthesized on an acid-treated Cu foil through variation of NaOH concentration from 0 to 50 mM with an in situ oxidation method. X-ray diffractometry and X-ray photoelectron spectroscopy (XPS) indicated formation of CuO on the Cu(OH)2 crystalline phase at a growth temperature of 60°C for 20 h. Antibacterial activity of the nanostructures against Escherichia coli bacteria was studied in the dark and under light irradiation. The nanostructures grown at a NaOH concentration of 30 mM showed the highest surface area and the strongest antibacterial activity among the samples. After elimination of the... 

TiO2 nanoparticles supported on activated carbon (AC) and multiwalled carbon nanotubes (MWCNTs) were prepared by the sol-gel method using ultrasonic irradiation. All the prepared samples were calcined at different temperatures and characterized by X-ray diffraction, nitrogen adsorption/desorption isotherms, scanning electron microscopy, transmission electron microscopy and diffuse reflectance spectroscopy. The effects of size and type of carbon on the morphology and photocatalytic activity of the resulting hybrid materials were investigated. The results showed that a decrease in the size of the carbon led to a decrease in size of TiO2 nanoparticles. Both AC and MWCNTs retarded the... 

Multi-component photocatalysts based on apatite-coated Ag=AgBr=TiO 2 were prepared by the deposition method. The effects of various kinds of apatites, with hydroxyl and fluoro substituents, on photocatalytic activity were investigated. The antibacterial processes in the dark, and under visible light, on two types of bacteria indicate that the multi-composites can inhibit the growth of bacteria by two different mechanisms. TEM images and optical microscopic data demonstrate that by attaching the nanosize catalyst to the outer membrane of the cell, the bacteria could not derive nourishment from surrounding media, i.e. this component acts as bacteria-static. The mechanism for deactivation of...