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Anodic behavior of clioquinol at a glassy carbon electrode
, Article Bioelectrochemistry ; Volume 80, Issue 2 , 2011 , Pages 175-181 ; 15675394 (ISSN) ; Fernandes, I. P. G ; Oliveira, S. C. B ; Shahrokhian, S ; Oliveira-Brett, A. M ; Sharif University of Technology
2011
Abstract
Clioquinol is an antifungal, antiprotozoal and an Alzheimer's disease drug with cytotoxic activity toward human cancer cells. The electrochemical behavior of clioquinol and its oxidation product was studied using cyclic, differential pulse and square-wave voltammetry over a wide pH range on a glassy carbon electrode. The results revealed that the oxidation of clioquinol is an irreversible pH-dependent process that proceeds with the transfer of one electron and one proton in an adsorption-controlled mechanism and results in the formation of a main oxidation product, which adsorbs very strongly on the glassy carbon surface. The charge transfer coefficient was calculated as 0.64. The adsorbed...
Visible light active Au:TiO2 nanocomposite photoanodes for water splitting: Sol-gel vs. sputtering
, Article Electrochimica Acta ; Volume 56, Issue 3 , January , 2011 , Pages 1150-1158 ; 00134686 (ISSN) ; Sangpour, P ; Moshfegh, A. Z ; Sharif University of Technology
2011
Abstract
In this study, pure TiO2 and Au:TiO2 nanocomposite thin films are both synthesized using sol-gel and RF reactive co-sputtering methods. Physical and photoelectrochemical properties of the thin films deposited by each method are compared. The optical density spectra and scanning electron microscopy images of the Au:TiO2 films reveal formation of gold nanoparticles in the all nanocomposite films synthesized by two methods. Moreover, the optical bandgap energy of the thin films decreases with addition of Au nanoparticles. X-ray photoelectron spectroscopy indicates that the presence of gold in metallic state and the formation of TiO2 is stoichiometric. The photoelectrochemical properties of the...
Al2O3/Si3N4 nanocomposite coating on aluminum alloy by the anodizing route: Fabrication, characterization, mechanical properties and electrochemical behavior
, Article Ceramics International ; 2016 ; 02728842 (ISSN) ; Afshar, A ; Ahmadi, S ; Sharif University of Technology
Abstract
An Al2O3/Si3N4 nanocomposite coating was successfully fabricated on commercial aluminum alloy. Hardness measurements, polarization and electrochemical impedance spectroscopy (EIS) were employed to study the mechanical and corrosion behaviors of the coatings. Field-Emission Scanning Electron Microscopy (FE-SEM) equipped with Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) were utilized to characterize the surface morphology and phase composition of the coatings. Also, coatings abrasive wear properties were evaluated with a modified ASTM G105 standard. FE-SEM image, EDS and XRD analysis revealed the presence of Si3N4 in the coating. Furthermore, the results showed hardness of...
Experimental Studies for Construction of a Microbial Fuel Cell (MFC) in Continuous Flow Mode
, M.Sc. Thesis Sharif University of Technology ; Vossoughi, Manoochehr (Supervisor) ; Aalemzadeh, Iran (Supervisor)
Abstract
In this research performance of microbial fuel cells (MFCs) in continuous flow mode was studied. Different anodic chambers were tested and it was found that granular activated carbons (GACs) produced the highest power density (1228 mW/m3) in comparison with multiple anodes (731 mW/m3), single anode (294 mW/m3) and polymeric packings (40 mW/m3). It was also shown that in a plug-anodic chamber (PAC) the power output is reduced by reducing agitation of anodic volume. Adding more GACs to anodic chamber results in power increase, however by increasing occupied volume from 80% to 100% the power increase was negligible in result of cathodic reactions limitations. Feed flowrate was increased from...
Effect of Solidification Rate of Copper Anodes on the Chemical and Electrochemical Dissolution during Electrorefining
, M.Sc. Thesis Sharif University of Technology ; Yoozbashizadeh, Hossein (Supervisor)
Abstract
In the present work,the effect of solidification rate on the electrochemical behavior of copperanodes of Sarcheshmeh copper complex has been studied.Inthis regard, three cylindrical coppers pecimens with different solidificationrates casted into water-cooled metal mold (A specimen), metal mold (B specimen) and sand mold (C specimen). Cylinders for microstructural and electrochemical investigation, alongthickness dividedinto several specimens. To investigate themicrostructure of the specimens, opticalmicroscopyand scanning electron microscopy(SEM)were used. ICP testhasbeen usedforelemental analysis of each specimen; and eventuallytoinvestigate theelectrochemical behavior ofeach of...
A Study on Properties of Composite Coating with Al2O3 Base Prepared by Hard Anodizing with ZrO2 Nanoparticles
, M.Sc. Thesis Sharif University of Technology ; Afshar, Abdollah (Supervisor)
Abstract
In this study anodized none composite and composite film containing ZrO2 nanoparticles were prepared on 1050 Al Alloy using hard anodizing method in sulfuric and oxalic acid mixed solution by pulse Currents. The microstructure and properties of the film were studied by field emission scanning electron microscopy with EDS analyzer and XRD diffraction and friction wear test were performed to evaluate the mechanical properties of coating . Results indicate that the composite film with ZrO2 nanoparticles have reduced friction coefficient with high micro hardness friction coefficient of composite film can be small as 0.16 which is much smaller than that 0.39 of none composite film. Micro hardness...
Enhanced dye loading-light harvesting TiO2 photoanode with screen printed nanorod-nanoparticles assembly for highly efficient solar cell
,
Article
Electrochimica Acta
;
Volume 169
,
2015
,
Pages 395-401
;
00134686 (ISSN)
; Siavash Moakhar, R
; Kushwaha, A
; Goh, G. K. L
; Riahi-Noori, N
; Sadrnezhaad, S. K
;
Sharif University of Technology
Elsevier Ltd
2015
Abstract
Morphology tailored TiO2 nano assemblies consisting of nanorods with and without nanoparticle attachments were hydrothermally synthesized and their characteristics and light scattering properties were determined by x-ray diffraction (XRD), nitrogen sorption analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), electrochemical impedance spectroscopy (EIS) and ultraviolet-visible spectroscopy (UV-Vis). The nanorod-nanoparticles (NR-NP) assemblies and smooth nanorod (NR) double layers were screen printed onto fluorine doped tin oxide coated glass underlayers to fabricate dye-sensitized solar cell (DSSC) photoanodes. The double layer heterogeneous...
Fabrication of a Sensor, Based on TiO2 Nanotubes Modified with Metal Nanoparticles and Carbon and its Application for Detection of Dopamine in Presence of Uric Acid and Ascorbic Acid
, Ph.D. Dissertation Sharif University of Technology ; Askari, Masoud (Supervisor) ; Dolati, Abolghasem (Supervisor)
Abstract
The present work describes sensing application of modified TiO2 nanotubes towards detection of dopamine. The TiO2 nanotubes electrode was prepared using anodizing method at different conditions, among which NaF/ NaHSO4 solution and voltage of 15 V was chosen as the optimum condition. In order to improve the performance, surface modification with metal nanoparticles (Pd, Pt and Au) and carbon is required using “pulse electrodeposition” and “decomposition of polyethylene glycol at 600 °C” respectively. Carbon was deposited by decomposition of polyethylene glycol in a tube furnace to improve the conductivity. In this regard two type of electrodes were proposed: Pd-Pt-Au-TiO2 and C-Ni(Pt)-TiO2....
Fabrication of Dental Implant from Ti-6Al-4V With Nanostructured Hydroxyapatite Coating
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhad, Khatiboleslam (Supervisor)
Abstract
The use of dental implants has grown considerably in recent years in Iran but this piece is the industrial imported parts that are not yet produced in Iran. So the main purpose of this research was to fabricate a dental implant from Ti-6Al-4V alloy by CNC machining techniques. On the other hand, the poor bonding strength of bioactive coatings and low cell growth on the surface of uncoated implants are the common problems in the use of dental implants. So another aim of this study was to investigate the effect of Nanoscale surface topography and nanostructured coatings on the surface modification of titanium implant in order to improve Osseointegration and the bonding strength of bioactive...
Hierarchical Co3O4/Co(OH)2 nanoflakes as a supercapacitor electrode: experimental and semi-empirical model
, Article ACS Applied Materials and Interfaces ; Volume 7, Issue 21 , 2015 , Pages 11172-11179 ; 19448244 (ISSN) ; Naseri, N ; Moshfegh, A. Z ; Sharif University of Technology
American Chemical Society
2015
Abstract
In this research, facile and low cost synthesis methods, electrodeposition at constant current density and anodization at various applied voltages, were used to produce hierarchical cobalt oxide/hydroxide nanoflakes on top of porous anodized cobalt layer. The maximum electrochemical capacitance of 601 mF cm-2 at scan rate of 2 mV s-1 was achieved for 30 V optimized anodization applied voltage with high stability. Morphology and surface chemical composition were determined by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. The size, thickness, and density of nanoflakes, as well as length of the porous anodized Co layer were measured about 460 ± 45 nm,...
Modification of nanostructured anodized aluminum coatings by pulse current mode
, Article Surface and Coatings Technology ; Volume 278 , 2015 , Pages 48-55 ; 02578972 (ISSN) ; Afshar, A ; Sharif University of Technology
Elsevier
2015
Abstract
In this study, the effects of pulse current mode on corrosion resistance and mechanical properties of anodized coatings were explored. Thickness and hardness measurements, polarization and electrochemical impedance spectroscopy were employed to take mechanical and corrosion behaviors of the anodized coatings into consideration. Also, field-emission scanning electron microscopy (FE-SEM) was utilized to characterize the surface morphology of the coatings. It was shown that in short anodizing times, coating thickness is controlled by the heat concentrated on coating. Although at prolonged anodizing times, the coating thickness is affected by average current density. Hardness measurements showed...
Hydrothermal synthesis of TiO2 nanocrystals in different basic pHs and their applications in dye sensitized solar cells
, Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 70 , June , 2015 , Pages 113-120 ; 13869477 (ISSN) ; Marandi, M ; Taghavinia, N ; Sharif University of Technology
Elsevier
2015
Abstract
In this research TiO2 nanocrystals with sizes about 11-70 nm were grown by hydrothermal method. The process was performed in basic autoclaving pH in the range of 8.0-12.0. The synthesized anatase phase TiO2 nanocrystals were then applied in the phtoanode of the dye sensitized solar cells. It was shown that the final average size of the nanocrystals was larger when the growth was carried out in higher autoclaving pHs. The photoanodes made of TiO2 nanocrystals prepared in the pHs of 8.0 and 9.0 represented low amounts of dye adsorption and light scattering. The performance of the corresponding dye sensitized solar cells was also not acceptable. Nevertheless, the energy conversion efficiency...
Comparison of the corrosion resistance of alkaline- and acid-anodized titanium
, Article Materials Performance ; Volume 54, Issue 1 , 2015 , Pages 51-55 ; 00941492 (ISSN) ; Ghahramani, S ; Afshar, A ; Malekinejad, P ; Sharif University of Technology
National Assoc. of Corrosion Engineers International
2015
Abstract
The process of self-color anodizing of titanium is done in acidic and alkaline solutions, and anodic films of different colors are formed. Results of this work show that the corrosion rate of titanium decreased after the application of an anodizing layer
Self-organized titanium oxide nanotubes prepared in phosphate electrolytes: Effect of voltage and fluorine concentration
, Article ECS Transactions, 25 April 2010 through 30 April 2010 ; Volume 28, Issue 7 , April , 2010 , Pages 67-74 ; 19385862 (ISSN) ; 9781607681830 (ISBN) ; Dolati, A ; Goodarzi, M ; Askari, M ; Ghahramaninezhad, A ; ECS All Divisions ; Sharif University of Technology
2010
Abstract
TiO2 a nanotube array was prepared using an anodization process. The process proceeded in a two-electrode cell containing of platinum sheet as the cathode electrode. Two phosphate-base electrolyte solutions containing different amounts of HF and NH4F were prepared. Different concentration of fluorine ions were examined in respected electrolytes. Current transient techniques were used to produce the TiO2 nanotubes at constant voltage of 18-25V. It was revealed that anodization at 18-22V, in so-called electrolytes would end up to nano-tubular structure. However the tubular structure prepared at 20V and from phosphate electrolyte containing of 0.5 wt% NH4F as well as 0.5 wt% HF, was recognized...
Diffusion-controlled growth model for electrodeposited cobalt nanowires in highly ordered aluminum oxide membrane
, Article ECS Transactions, 25 April 2010 through 30 April 2010, Vancouver, BC ; Volume 28, Issue 17 , 2010 , Pages 13-25 ; 19385862 (ISSN) ; 9781607681939 (ISBN) ; Dolati, A ; Sharif University of Technology
2010
Abstract
This work studies the electrochemical growth behavior of cobalt nanowires in highly ordered aluminum oxide membrane. Considering the electrodeposition of metallic nanowires, cation concentration profile in each nano pore was calculated. With assumption of linear diffusion zone on the growing surface of nanowires, a modified Cottrell equation was evaluated. To confirm the model, the Co nanowires were electrodeposited into porous anodic aluminum oxide (AAO) templates and the mechanism of deposition was studied. Comparing the results of model and the experiments has proved the accuracy of the model. Also, it was observed that the growth of the Co nanowires was controlled mainly by diffusion...
Synthesis of Doped Titania Nanotube Arrays by Anodizing of Titanium and Surveying of their band Gap
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
In recent decade, photocatalystic properties of titania nanotube and its mechanisms has been considered greatly in many researches. One of the major ways to increase photocatalystic properties and extending the usage of TNTs is doping them with various elements and modifying their band structure. In present research doped TNTs were prepared by doping of Molybdenum, Nitrogen, and Carbon elements by anodizing method in about of 35 degrees of centigrade and constant voltage of 20V on the surface of titanium sheet. Structural and photocatalystic properties of as-prepared TNTs were studied using field emission scanning electron microscope (FESEM), x-ray diffraction (XRD), energy dispersive...
Electrochemical oxidation of saccharose on copper (hydr)oxide-modified electrode in alkaline media
, Article Cuihua Xuebao/Chinese Journal of Catalysis ; Volume 31, Issue 11 , 2010 , Pages 1351-1357 ; 02539837 (ISSN) ; Rashvand Avei, M ; Danaee, I ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
2010
Abstract
A stable copper (hydr)oxide-modified electrode was prepared in 0.5 mol/L NaOH solution by cyclic voltammetry in the range of -250 to 1000 mV. It can be used for electrochemical studies in the range of -250 to 1000 mV without interfering peaks because there is no oxidation of copper. During an anodic potential sweep, the electro-oxidation of saccharose on Cu occurred by the formation of CuIII and this reaction also occurred in the early stages of the reversed cycle until it is stopped by the negative potentials. A mechanism based on the electro-chemical generation of CuIII active sites and their subsequent consumption by saccharose was proposed, and the rate law and kinetic parameters were...
New smart carrageenan-based superabsorbent hydrogel hybrid: Investigation of swelling rate and environmental responsiveness
, Article Journal of Applied Polymer Science ; Volume 117, Issue 6 , September , 2010 , Pages 3228-3238 ; 00218995 (ISSN) ; Pourjavadi, A ; Seidi, F ; Eftekhar Jahromi, P ; Soleyman, R ; Sharif University of Technology
2010
Abstract
Synthesis of novel natural-based superabsorbents with improved properties is of prime importance in many applications. In this article we report an efficient synthesis of new polysaccharide-based superabsorbent hybrid composing carrageenan, acrylic acid, sodium acrylate, and 2-hydroxyethyl acrylate through homogenous solution polymerization process. Infrared spectroscopy and thermogravimetric analysis (TGA) were carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was examined by scanning electron microscopy (SEM). To deeper studies on the structure-property relation in SAP hydrogels, three hydrogels with different acrylic acid/2-hydroxyethyl...
Fabrication of self-organised highly ordered titanium oxide nanotube arrays by anodic oxidation and characterisation
, Article International Journal of Nanomanufacturing ; Volume 5, Issue 3-4 , 2010 , Pages 297-309 ; 17469392 (ISSN) ; Ahadian, M. M ; Iraji Zad, A ; Taghavinia, N ; Dolati, A. G ; Sharif University of Technology
2010
Abstract
Self-organised and vertically oriented titanium oxide nanotube array (TNTA) has been synthesised by potentiostat anodisation of Ti foil in fluoride-based electrolyte. By varying the anodisation voltage from 8 V to 24 V it was possible to gradually change the topologies of nanotubes. The size of TNTAs was measured using SEM images and also determined based on a non-destructive optical method. In addition, photoelectrochemical properties of nanotubular TiO2/Ti electrodes were examined by anodic photocurrent response, potentiodynamic polarisation measurements and electrochemical impedance spectroscopy. A general equivalent circuit model was proposed for photoelectrochemical system consists of...
Electrochemically Assisted Photocatalytic Oxidation of Methanol on TiO2 Nanotube Arrays
, Article Journal of Materials Science and Technology ; Volume 26, Issue 6 , June , 2010 , Pages 535-541 ; 10050302 (ISSN) ; Irajizad, A ; Taghavinia, N ; Rahman, M ; Ahadian, M. M ; Sharif University of Technology
2010
Abstract
The influence of an externally applied bias on photocatalytic performance of crystallized TiO2/Ti nanotubular electrode formed by anodization in fluoride-based electrolyte were investigated and compared to the behavior of multiporous TiO2 electrode. The photoelectrocatalytic oxidation behavior of methanol over the nanotubular electrode has been studied by measuring photocurrent response, potentiodynamic polarization spectroscopy and using electrochemical impedance spectroscopy (EIS). It was found that the photoelectrocatalytic oxidation and the charge transfer rate constant of reaction on TiO2/Ti nanotubular electrode can significantly be increased by applying electrochemical bias. Moreover,...