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Talebian N.,Islamic Azad University at Shahreza | Nilforoushan M.R.,Sharekord University
Thin Solid Films | Year: 2010

Indium oxide (In2O3), zinc oxide (ZnO), stannic oxide (SnO2), and titanium dioxide (TiO2) thin films were prepared on glass substrates using electron beam evaporation. The samples characterized by UV-vis spectroscopy, diffraction ray-X and scanning electron microscopy techniques. The photocatalytic degradation of methylene blue in an aqueous solution, as a model compound, was investigated using different metal oxides in an attempt to compare the decomposition reaction rate. The progress of degradation was monitored using UV-vis spectrophotometry. The effects of various experimental parameters such as initial concentration of methylene blue (5-10 mg/l), pH of the solution (2-8), annealing temperature (250-550 °C), and catalyst nature and its microstructure were systematically studied in order to achieve maximum degradation efficiency. The results obtained were fitted with the Langmuir-Hinshelwood model to study the degradation kinetics and discussed in detail. Nearly complete degradation was obtained at optimal operational parameters including the higher annealing temperature of thin film and the increase in MB solution pH. The degradation with In2O3 was more efficient than with SnO2, ZnO and TiO2 films. © 2009 Elsevier B.V. All rights reserved. Source


Talebian N.,Islamic Azad University at Shahreza | Nilforoushan M.R.,Sharekord University | Mogaddas F.J.,Islamic Azad University at Shahreza
Ceramics International | Year: 2013

The enhanced sonophotocatalytic degradation of Chrome Intra Orange G (C.I. 18745), an azo dye, in aqueous solution under UV light has been carried out using solvothermally sensitized ZnO nanoparticles as catalyst. The effects of sonolysis, sonocatalysis, photocatalysis and sonophotocatalysis have been examined to study the influences on the degradation rates by varying the initial dye concentration, dye solution pH, catalyst morphology and loading to ascertain the synergistic effect on the degradation techniques. ZnO sonophotocatalysis was always faster than the respective individual processes. Ultrasound may modify the rate of photocatalytic degradation by promoting the deaggregation of the catalyst and ultrasound-induced increase of its active surface area, by increasing the amount of reactive radical species through cavitation leading to water splitting and formation of H2O 2 by both photocatalysis and sonolysis. To further verify the direct relation of the effective surface area offered by ZnO to its reaction rate, sonophotocatalysis experiments were conducted using nanorods of different dimensions and aspect ratios. Higher aspect ratio values correspond to an enhancement of the sonophotocatalytic activity. © 2012 Elsevier Ltd and Techna Group S.r.l. Source


Talebian N.,Islamic Azad University at Shahreza | Nilforoushan M.R.,Sharekord University | Zargar E.B.,Islamic Azad University at Shahreza
Applied Surface Science | Year: 2011

The nano-sized coupled oxides ZnO/SnO 2 thin films in a molar ratio of 2:1 (Z2S), 1:1 (ZS) and 1:2 (ZS2) were prepared using sol-gel dip coating method and characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis spectroscopy. Escherichia coli (E. coli, ATCC 25922) was selected as a model for the Gram-negative bacteria to evaluate antibacterial property of composite samples compared with single ZnO (Z) and single SnO 2 (S) films. The antibacterial activity has been studied applying the so-called antibacterial drop test under UV illumination. The bactericidal activity was estimated by relative number of bacteria survived calculated from the number of viable cells which form colonies on the nutrient agar plates. The influence of the SnO 2-ZnO nanocomposite composition on the structural features and on the antibacterial properties of the thin films are reported and discussed. It is found that all coatings exhibited a high antibacterial activity. The coupled oxide photocatalyst Z2S has better photocatalytic activity to bacteria inactivation than ZS, ZS2, Z and S films. Furthermore, nanostructured films were active even in the absence of irradiation. © 2011 Elsevier B.V. All rights reserved. Source


Talebian N.,Islamic Azad University at Shahreza | Nilforoushan M.R.,Sharekord University | Salehi Z.,Islamic Azad University at Shahreza
Ceramics International | Year: 2012

In the present study, the effects of the heterojunctions on the optical and structural characteristics and the resulting photocatalytic properties of multilayered ZnO-based thin films were investigated. The junctions were composed of semiconducting ZnO nano-porous films coated on the In 2O 3 and SnO 2 counterpart layers. The multilayered ZnO films based on the triple-layered Ag-doped indium oxide (AIO)/tin oxide (TO)/zinc oxide (ZnO), indium oxide (IO)/Ag-doped tin oxide (ATO)/zinc oxide (ZnO), indium oxide (IO)/tin oxide (TO)/zinc oxide (ZnO) and tin oxide (TO)/indium oxide (IO)/zinc oxide (ZnO) have been fabricated by subsequent sol-gel dip coating. Their structural and optical properties combined with photocatalytic characteristics were examined toward degradation of Solantine Brown BRL (C.I. Direct Brown), an azo dye using in Iran textile industries as organic model under UV light irradiation. Effects of operational parameters such as initial concentration of azo dye, irradiation time, solution pH, absence and presence of Ag doping and consequent of sublayers on the photodegradation efficiencies of ZnO nultilayered thin films were also investigated and optimum conditions were established. It was found that the photocatalytic degradation of azo dye on the composite films followed pseudo-first order kinetics. Photocatalytic activity of AIO/TO/ZnO interface composite film was higher compared with other films and the following order was observed for films activities: AIO/TO/ZnO > IO/TO/ZnO > ATO/IO/ZnO > TO/IO/ZnO. Differences in the film efficiencies can be attributed to differences in crystallinity, interfacial lattice mismatch, and surface morphology. Besides, the presence of Ag doping between layers that may act as trap for electrons generated in the ZnO over layer thus preventing electron-hole recombination. © 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Source


Talebian N.,Islamic Azad University at Shahreza | Nilforoushan M.R.,Sharekord University | Memarnezhad P.,Islamic Azad University at Shahreza
Journal of Sol-Gel Science and Technology | Year: 2013

In present study, ZnO/SnO2/ZnO/SnO2/ZnO multi-layer, ZnO/SnO2/ZnO triple layer and ZnO single layer films have been deposited on glass substrate by sol-gel dip-coating technique. The structural and optical properties of thin films have been investigated by X-ray diffractometer, UV-visible, photoluminescence spectroscopies and scanning electron microscopy. The structural analysis reveals structural inhomogeneities and different crystallite growth processes as function of number of deposited layers. A comparison between photocatalytic activity of zinc oxide samples toward photodegradation of phenol, 4-aminophenol and 4-nitrophenol has been performed under UV light irradiation. Experiments were conducted to study the effects of operational parameters on the degradation rate. Pseudo-first-order photodegradation kinetics was observed on all films and the reaction constants were determined. The results showed that the photocatalytic activity of ZnO multi-layer film was superior to that of the ZnO single- and triple-layer films. Differences in film efficiencies can be attributed to differences in crystallinity, surface morphology, defect concentration of oxygen vacancy and to presence of SnO2 sublayer that may act as trap for electrons generated in the ZnO layer thus preventing electron-hole recombination. The results reveal that SnO2 hetrojunction layers improve crystalline quality, optical and photocatalytic properties of ZnO multilayered films. © 2012 Springer Science+Business Media New York. Source

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