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Colloidal stability of dextran and dextran/poly ethylene glycol coated TiO2 nanoparticles by hydrothermal assisted sol-gel method
, Article Ceramics International ; Volume 39, Issue 7 , 2013 , Pages 8377-8384 ; 02728842 (ISSN) ; Madaah Hosseini, H. R ; Faghihi Sani, M. A ; Sharif University of Technology
2013
Abstract
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...
Improved efficiency of dye-sensitized solar cells by design of a proper double layer photoanode electrodes composed of Cr-doped TiO2 transparent and light scattering layers
, Article Journal of Sol-Gel Science and Technology ; Volume 67, Issue 1 , 2013 , Pages 77-87 ; 09280707 (ISSN) ; Bakhshayesh, A. M ; Sadri, F ; Masroor, M ; Sharif University of Technology
2013
Abstract
A new strategy for enhancing the efficiency of TiO2 dye-sensitized solar cells (DSSCs) by design of a new double layer film doped with Cr ions, with various morphologies, is reported. X-ray diffraction and field emission scanning electron microscope (FE-SEM) analyses revealed that the synthesized nanoparticles had uniform and nanometer grains with different phase compositions and average crystallite size in the range of 10-12 nm depending upon Cr atomic percentage. UV-vis absorption showed that Cr introduction enhanced the visible light absorption of TiO2 nanoparticles by shifting the absorption onset to visible light region. Furthermore, the band gap energy of nanoparticles decreased with...
Fabrication of nanoporous nickel oxide by de-zincification of Zn-Ni/(TiO2-nanotubes) for use in electrochemical supercapacitors
, Article Electrochimica Acta ; Volume 100 , 2013 , Pages 133-139 ; 00134686 (ISSN) ; Faraji, M ; Sharif University of Technology
2013
Abstract
NiO-ZnO/TiO2NTs electrodes were synthesized by the electrodeposition of Zn-Ni onto TiO2 nanotubes, dealloying in a concentrated alkaline solution and finally calcination of the resulting Zn(OH)2-Ni(OH)2/TiO2NTs at 300 C. Morphology of the electrodeposited nanostructures was studied using scanning electron microscopy (SEM) while their electrochemical characterizations were carried out using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge procedures. The SEM analysis revealed the nanoporous/cracked structures of the NiO-ZnO/TiO2NTs obtained at the electroplating time of 20 min. The EIS studies showed that nanoporous/cracked structures of...
Synthesis and characterization of TiO2-graphene nanocomposites modified with noble metals as a photocatalyst for degradation of pollutants
, Article Applied Catalysis A: General ; Volume 462-463 , 2013 , Pages 82-90 ; 0926860X (ISSN) ; Esfandiar, A ; Rahman Setayesh, S ; Habibi Yangjeh, A ; Iraji Zad, A ; Gholami, M. R ; Sharif University of Technology
2013
Abstract
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...
Hydroxyapatite nanocomposites: Synthesis, sintering and mechanical properties
, Article Ceramics International ; Volume 39, Issue 3 , April , 2013 , Pages 2197-2206 ; 02728842 (ISSN) ; Eskandari, A ; Baroonian, M. H ; Berenov, A ; Razavi Hesabi, Z ; Taheri, M ; Sadrnezhaad, S. K ; Sharif University of Technology
2013
Abstract
Two different hydroxyapatite based composites reinforced by oxide ceramic (20 wt%) nano crystals were synthesized by high-energy ball milling and sintered by pressure less technique. Alumina and titania nanoparticles as secondary phases improved densification and mechanical behavior of apatite and postponed its decomposition to the tricalcium phosphate (TCP) phases at elevated temperatures. Increasing the relative density of apatite using nano reinforcements leads to enhance the bending strength by more than 40% and 27% (as compared to the pure HA) and increase the hardness from 2.52 to 5.12 (Al2O3 composite) and 4.21 (TiO2 addition) GPa, respectively. Transmission electron microscopy (TEM),...
Freestanding light scattering hollow silver spheres prepared by a facile sacrificial templating method and their application in dye-sensitized solar cells
, Article Journal of Power Sources ; Volume 225 , 2013 , Pages 46-50 ; 03787753 (ISSN) ; Dadgostar, S ; Taghavinia, N ; Iraji Zad, A ; Sharif University of Technology
2013
Abstract
Hollow silver microspheres are synthesized in an easy and environmentally friendly process by a sacrificial templating method. Carbonaceous microspheres (CMSs) are used as hard templates, which have been synthesized previously by a hydrothermal carbonization process. Hollow silver spheres (HSSs) are synthesized by thermal removal of the core carbon component. The thickness of shell could be controlled by the concentration of precursors. Depending on the thickness, uniform or discontinuous shells are formed. The spheres are coated with SiO 2, and then added into the electrolyte of a dye solar cell. The enhancement of 50% is achieved in short-circuit current density (JSC) due to the scattering...
Improved efficiency of dye-sensitized solar cells aided by corn-like TiO2 nanowires as the light scattering layer
, Article Electrochimica Acta ; Volume 90 , 2013 , Pages 302-308 ; 00134686 (ISSN) ; Mohammadi, M. R ; Dadar, H ; Fray, D. J ; Sharif University of Technology
2013
Abstract
We present a new TiO2 morphology, featuring highly crystalline anatase structure, synthesized by a two consecutive hydrothermal operation for the manufacture of dye-sensitized solar cells (DSSCs). This construct is a one-dimensional (1D) nanostructure (i.e., nanowire) with interconnected nanoparticles on the surface with a large percentage of reactive facets, so called corn-like nanowire. Such morphology is produced by a surface modification concept using surface tension stress mechanism. The double layer DSSC made of anatase-TiO2 nanoparticles as the under-layer and corn-like TiO 2 nanowires as the over-layer (as light scattering layer) shows higher conversion efficiency of 7.11% and short...
Construction of a modified carbon paste electrode based on TiO2 nanoparticles for the determination of gallic acid
, Article Journal of Solid State Electrochemistry ; Volume 17, Issue 1 , 2013 , Pages 157-165 ; 14328488 (ISSN) ; Nami Ana, S. F ; Hashemnia, S ; Hormozi Nezhad, M. R ; Sharif University of Technology
2013
Abstract
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...
Adverse effects of graphene incorporated in TiO 2 photocatalyst on minuscule animals under solar light irradiation
, Article Journal of Materials Chemistry ; Volume 22, Issue 43 , 2012 , Pages 23260-23266 ; 09599428 (ISSN) ; Ghaderi, E ; Rahimi, K ; Sharif University of Technology
2012
Abstract
The adverse effect of graphene-titanium oxide composite films (containing sheet-like surface morphology) on Caenorhabditis elegans nematodes (as a model for minuscule animals) was investigated in a solar light-induced photocatalytic process. X-ray photoelectron spectroscopy demonstrated photocatalytic reduction of the chemically exfoliated graphene oxide sheets included in the TiO 2 film. Furthermore, formation of TiC and Ti-O-C bonds in the composite film (obtained through annealing at 450 °C in air) resulted in a substantial delay in the recombination rate of the photoexcited electron-hole pairs and more efficient photocatalytic processes. The composite film showed a type of...
MAO-derived hydroxyapatite-TiO 2 nanostructured bio-ceramic films on titanium
, Article Materials Research Bulletin ; Volume 47, Issue 11 , 2012 , Pages 3407-3412 ; 00255408 (ISSN) ; Golestani Fard, F ; Rezaie, H. R ; Mirhosseini, S. M. M ; Ziaee, A ; Sharif University of Technology
2012
Abstract
Micro Arc Oxidation (MAO) process was utilized to fabricate nano bioceramic TiO 2-hydroxyapatite coatings on titanium substrates. Samples were produced in electrolytes contained 1 g/l β-glycerophosphate and 5, 10 and 15 g/l calcium acetate for 3, 6 and 10 min at 350 V. The techniques including XRD, XPS, SEM, FESEM and EDX were employed to study the effect of processing parameters. Hydroxyapatite, anatase, α-tri calcium phosphate and calcium titanate phases as well as 30-60 nm-size crystals were detected in the coating layer. It was also observed that the pore volume would increase by increasing the electrolyte concentration. The growth time was also found to influence the total pore volume....
Removal of an organic pollutant from waste water by photocatalytic behavior of AgX/TiO2 loaded on mordenite nanocrystals
, Article Research on Chemical Intermediates ; Volume 38, Issue 8 , 2012 , Pages 1975-1985 ; 09226168 (ISSN) ; Salari, H ; Ahmadvand, S ; Gholami, M. R ; Sharif University of Technology
Springer
2012
Abstract
Mordenite (MOR) nanocrystals were synthesized using the hydrothermal method. Sol-gel and deposition methods were utilized to modify the zeolite surface with TiO2 and then AgBr or AgCl particles. Photocatalysts were characterized by using X-ray diffraction, Brunauer-Emmett-Teller (BET), and scanning electron microscopy techniques. Activity was evaluated by photodegradation of Acid Blue 92 as an azo dye. The effect of silver halide deposition on the photocatalytic behavior of the prepared nanocomposites was studied under both ultraviolet (UV) and visible light, and the results were compared. The results showed that AgCl/TiO2/MOR was more active under UV, while with visible source,...
Tailoring of morphology and crystal structure of nanomaterials in MgO-TiO 2 system by controlling Mg:Ti molar ratio
, Article Journal of Sol-Gel Science and Technology ; Volume 64, Issue 1 , October , 2012 , Pages 135-144 ; 09280707 (ISSN) ; Fray, D. J ; Sharif University of Technology
Springer
2012
Abstract
The morphological manipulation and structural characterisation of TiO 2-MgO binary system by an aqueous particulate sol-gel route were reported. Different crystal structures including pure MgTiO 3, mixtures of MgTiO 3 and TiO 2 and mixtures of MgTiO 3 and Mg 2TiO 4 were tailored by controlling Mg:Ti molar ratio and annealing temperatures as the processing parameters. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) revealed that all compounds crystallised at the low temperature of 500 °C. Furthermore, it was found that the average crystallite size of the compounds depends upon the Mg:Ti molar ratio as well as the annealing temperature, being in the range 3-5 nm at...
Effects of ion-exchange and hydrolysis mechanisms on lead silicate glass corrosion
, Article Corrosion ; Volume 68, Issue 9 , September , 2012 , Pages 793-800 ; 00109312 (ISSN) ; Sadrnezhaad, S. K ; Sharif University of Technology
2012
Abstract
Corrosion of lead silicate glass (LSG) contacting 0.5 M aqueous nitric acid (HNO 3) was investigated via scanning electron microscopy, energy-dispersive spectroscopy, inductively coupled plasma analysis, and weight-loss measurement to determine the respective contributions of the ion-exchange vs. the hydrolysis reactions. The LSG having X M ≡ Pb+K+Na/Si mole ratios of less than 0.7 showed very little weight loss with no Si network deterioration. At X M > 0.7, the mechanism changed into the hydrolysis, which caused the formation of a networkless gel layer resting at the solid/liquid interface. Addition of titania (TiO 2) and zirconia (ZrO 2) had disparate effects: X M < 0.7 improved corrosion...
Photoactive and self-cleaning TiO 2-SiO 2 thin films on 316L stainless steel
, Article Thin Solid Films ; Volume 520, Issue 20 , 2012 , Pages 6355-6360 ; 00406090 (ISSN) ; Afshar, A ; Dolati, A ; Sharif University of Technology
Abstract
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...
The influence of chromium substitution on an iron-titanium catalyst used in the selective catalytic reduction of NO
, Article Journal of Catalysis ; Volume 292 , August , 2012 , Pages 32-43 ; 00219517 (ISSN) ; Salehi, V ; Sharif University of Technology
Elsevier
2012
Abstract
A series of Cr-substituted Fe-Ti compounds were prepared by the co-precipitation method and were systematically investigated as catalysts for the selective catalytic reduction (SCR) of NO by NH 3. A variety of analytical techniques revealed that the Cr substitution amount affects the N 2 selectivity, SCR activity, redox behavior of NH 3/NO x, adsorption ability, and structure of catalysts in terms of surface properties, porosity, mobility of lattice oxygen, oxidative ability of Cr species, ratio of Bronsted acid sites and Lewis acid sites, NO x adsorption capacity, and structural disorder and distortion. In a series of Fe aCr 1-aTiO x (a = 1, 0.75, 0.5, 0.2, 0) catalysts, Fe 0.5Cr 0.5TiO x...
Investigation of the antibacterial and photocatalytic properties of the zeolitic nanosized AgBr/TiO 2 composites
, Article Materials Science in Semiconductor Processing ; Volume 15, Issue 1 , February , 2012 , Pages 73-79 ; 13698001 (ISSN) ; Elahifard, M. R ; Vatan Meidanshahi, R ; Ghasemi, S ; Haghighi, S ; Gholami, M. R ; Sharif University of Technology
2012
Abstract
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...
Photocatalytic activity of TiO 2-capped ZnO nanoparticles
, Article Journal of Materials Science: Materials in Electronics ; Volume 23, Issue 2 , 2012 , Pages 361-369 ; 09574522 (ISSN) ; Simchi, A ; Nemati, Z. A ; Sharif University of Technology
Abstract
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....
Catalytic activity of TiO 2 nanotubes modified with carbon and Pt nanoparticles for detection of dopamine
, Article ECS Transactions ; Volume 35, Issue 35 , 2011 , Pages 53-62 ; 19385862 (ISSN) ; 9781607682950 (ISBN) ; Mahshid, S. S ; Ghahremaninezhad, A ; Askari, M ; Dolati, A ; Yang, L ; Luo, Sh ; Cai, Q ; Sensor; Organic and Biological Electrochemistry ; Sharif University of Technology
2011
Abstract
Catalytic activity of carbon/Pt nanoparticles modified TiO 2 nanotubes electrode was studied by using dopamine contained solutions. The TiO 2 nanotubes electrode was prepared using anodizing method in aqueous solution. The electrochemical pulse method was then applied for electrodeposition of Pt nanoparticles onto the TiO 2 nanotubes. Further modification was achieved by decomposition of polyethylene glycol in a tube furnace to have a carbon/Pt nanoparticles modified TiO 2 nanotubes electrode. The final modified electrode could successfully detect the electro-oxidation of dopamine in a ImM contained solution using cyclic voltametry method. Also, a high sensitivity towards the oxidation of...
Preparation and characterization of PES and PSU membrane humidifiers
, Article Journal of Membrane Science ; Volume 383, Issue 1-2 , 2011 , Pages 197-205 ; 03767388 (ISSN) ; Mousavi, S. A ; Moallemzadeh, A ; Roostaazad, R ; Hesampour, M ; Pihlajamaki, A ; Manttari, M ; Sharif University of Technology
Abstract
Polysulfone (PSU) and polyethersulfone (PES) porous membranes; and mixed polymer with nanoparticles TiO2, were prepared for air humidification. The mechanical properties and morphology of these membranes were studied by Tensile tester and SEM/EDX. The effects of membrane composition and operating factors on humidifier performance were investigated. The results revealed that the membrane composition and its structure have significant effect on humidification. The porous membranes with finger type cavities had higher humidification performance but lower mechanical properties. Water flux of the membranes was about 0.16-0.2L/hm2 at 25°C. Furthermore, adding 0.1wt% TiO2 nanoparticles to casting...
Gel-sol synthesis and aging effect on highly crystalline anatase nanopowder
, Article Bulletin of Materials Science ; Volume 34, Issue 6 , October , 2011 , Pages 1189-1195 ; 02504707 (ISSN) ; Askari, M ; Sadrnezhaad, S. K ; Sharif University of Technology
2011
Abstract
Highly crystalline TiO 2 anatase nanoparticles were synthesized via gel-sol method by using titanium isopropoxide and triethanolamine. The products were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric/differential thermal analysis and nitrogen gas absorption methods. The particle size ranged from 7 to 24 nm having specific surface area of 64 to 220 m 2/g. Selective Ti(OH) 4 gel specifications and hydrothermal test conditions resulted in thermodynamically- stable phase-formation. Aging at 130°C for 4 h resulted in particle size of 7 nm; while at 130 and 160°C for 12 h resulted in 12 and 21 nm, respectively