Search for: electrochemical-methods
Total 37 records
Deposition of Nanoporous Metallic Thin Films by Sputtering and Comparing with Electrochemical Method (Electroplating), M.Sc. Thesis Sharif University of Technology ; Rashidian, Bijan
Porous thin films have becom very atractive due to their applications in many types of electronic and optical devices. There are several methods for deposition of such films. Chemical method for deposition of nanoporous thin films are relatively simple, but usually hard to control. In this thesis, chemical deposition of thin porous Molybden films is reported. In addition, an available sputtering system has been modified and, controlled porosity thin films were then deposited on glass and silicon substrates using GLAD method.These films have been characerized, and compared with chemically deposited porous thin films
Effect of potential on the early stage of nucleation and growth during aluminum electrocrystallization from molten salt (AlCl3-NaCl-KCl), Article Journal of Electroanalytical Chemistry ; Volume 588, Issue 2 , 2006 , Pages 190-196 ; 15726657 (ISSN) ; Mahjani, M. G ; Gobal, F ; Danaee, I ; Sharif University of Technology
Electrodeposition of aluminum onto graphite from a molten electrolyte containing AlCl3-NaCl-KCl was studied by the method of chronoamperometery. In the early stage of the deposition and at low cathodic potentials two-dimensional (2D) nucleation and growth proceeding through instantaneous and a multitude of progressive steps followed the initial double layer charging. The processes are manifested as peaks on a decaying chronoamperogram. Non-linear fitting methods were applied to obtain the kinetic parameters in the light of Bewick, Fleischmann and Thirsk (BFT) theory. Under more cathodic potentials, transition from 2D to three-dimensional (3D) processes have been observed as manifested in the...
Synthesis of Graphene Nanosheets for Application in Biosensors, M.Sc. Thesis Sharif University of Technology ; Akhavan, Omid
Graphene, the newborn nanomaterial whose unique properties has extensively drawnattention of many scientists in the recent years, is an ideal candidate for sensing applications due to its exclusive properties like extremely high specific surface area, excellent electrical conductivity, andcapability of being easily functionalized. In this research, after reviewing the attempts already performed on detection of DNA, in order to detect the four bases of DNA (G, A, T, and C) via electrochemical approach, graphene nanosheets were synthesized by the popular Hummer’s method and were deposited on a graphite rod by electrophoretic deposition with a vertical preferred orientation. To eliminate the...
Electrochromism: An emerging and promising approach in (bio)sensing technology, Article Materials Today ; Volume 50 , 2021 , Pages 476-498 ; 13697021 (ISSN) ; Ranjbar, S ; Parolo, C ; Nguyen, E. P ; Álvarez Diduk, R ; Hormozi Nezhad, M. R ; Merkoçi, A ; Sharif University of Technology
Elsevier B.V 2021
Electrochromism (EC) is a unique property of certain materials that undergo an electrochemical-induced change in colouration. During the last decades, electrochromic materials (ECMs) have been applied in a variety of technologies ranging from smart windows to information displays and energy storage devices. More recently, ECMs have attracted the attention of the (bio)sensing community thanks to their ability to combine the sensitivity of electrochemical methods with the intuitive readout of optical sensors. Although still a nascent technology, EC-based sensors are on the rise with several targets (e.g. cancer biomarkers, bacteria, metabolites and pesticides), which have already been detected...
Nanostructural Coating of Al2O3 on NiTi Alloy Via Electrochemical Method for Improvement of Biomedical and Surface Properties, M.Sc. Thesis Sharif University of Technology ; Sadrnezhaad, Khatiboleslam
Nitinol alloy is important and increasingly used in medicine and industry due to its unique properties such as shape memory and superelasticity. Plasma Electrolytic Oxidation (PEO) is a relatively new method which in electrical discharge occurrence and formation of small plasma arcs on the anode surface and the electrochemical and thermochemical reactions in plasma environment prepare ceramic coating on the substrate. This method is taken into consideration because of its simplicity and effectiveness in the preparation of oxide ceramic coatings with porous structure on the surface of certain metals and alloys to improve their corrosion and wear properties. In this study, to improve the...
Preparation and Physico-chemical Characterization of Titanium Dioxide Nanotubes with Electrochemical Method for Oxidative Dehydrogenation of Propane (ODHP), M.Sc. Thesis Sharif University of Technology ; Kazemeini, mohammad
Samples of the V2O5 catalysts supported on nanostructures of TiO2 and γ-Al2O3 were synthesized via hydrothermal method for the oxidative dehydrogenation of propane (ODHP) to propylene. The TiO2 support was utilized in both commercial microstructures and prepared nanostructures from their corresponding salts. Furthermore,the γ-Al2O3 was also prepared from two novel methods. Moreover, the vanadium catalysts supported on hybrid TiO2 and γ-Al2O3 were prepared. The performances of the prepared catalysts were subsequently examined in a fixed-bed reactor. The main products were propylene, ethylene and COx.The vanadium catalyst over TiO2 and γ-Al2O3 had the best performance under the reactor test...
Study on the Exfoliation of Graphite into Graphene by Electrochemical Method and Its Application in Thermoplastic Polyurethane Nanocomposite, M.Sc. Thesis Sharif University of Technology ; Pircheraghi, Gholamreza
Graphene is two dimensional nanomaterial, single layer of carbon atoms that exhibited excellent properties like high electrical conductivity and stiffness, but producing graphene and obtaining a good dispersion of graphene in a polymer matrix is still a major challenge. In this study by using the electrochemical route several graphene with different degree of oxidation produced in different electrolyte medium. According to XRD data, product of electrochemical exfoliation in dilute HNO3 medium includes 50% few-layer graphene (5 layers) and 25% GO and the rest are multi-layer graphene. Nonsolvent induced phase separation method were used to prepare TPU/Graphene nanocomposite. Different methods...
Blackening on Steel by Electrochemical Method, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad
In this study, the magnetite protective oxide layer was successfully formed on carbon steel substrate in an alkaline solution by an electrochemical method. The electroblackening was performed at a constant potential of 2 volts and in a 50 wt% solution at 75 ° C for 10 minutes. The properties of coating characterized using X-ray diffraction, field emission-scanning electron microscopy, polarization test and visible light spectrophotometery and porosity and thickness of oxide coating investigated. By adding 50 grams per liter of each of nitrate and chromate oxidizers, the porosity of oxide coating decreased from 24 percent to 14 percent and coating thickness increased from 1 micron to 3...
Electrochemical Desulfurization of Sample Oil, Ph.D. Dissertation Sharif University of Technology ; Farhadi, Fatolla ; Shahrokhi, Mohammad
Since, presence of sulfur compounds in fuels leads to environmental pollution and deacrese of fuel quality, fuel desulfurization should be considered for enhancing the fuel charachteristics. Electrochemical desulfurization was recogonized as one of desulfurization techniques that uses anode and cathode in an electrolytic environment under mild temperature and pressure. In this research, electrochemical desulfurization of crude gas-oil has been studied over electrodes of copper and stainless steel in the presence of NaOH and sulfuric acid. In this research, the effects of operational prameters like stirring rate, temperature, applied potential, sodium hydroxide/sulfuric acid addition as...
Investigation on Parameters of Carbon Nanotubes Growth and Effect of Interaction between H2 Gas and their Surfaces and Determining Capacity of Hydrogen Storage, Ph.D. Dissertation Sharif University of Technology ; Moshfegh, Alireza ; Nozad, Ahmad
In this study, growth of MWCNTs in form of thin film and powder for hydrogen storage was investigated. Different analytical techniques including SEM, TEM, STA, XRD, XPS, BET, BJH and Raman spectroscopy were applied to characterize the samples. The results showed that substrate, catalyst thickness and type of catalyst are influenced in yield of the growth, structure and quality of MWCNTs. The study has also indicated that MWCNTs grown on Fe-Pd bimetallic catalyst with 25-75 proportion had the highest growth yield. Moreover, decreasing of the growth temperature from 970 to 920 oC produced single-walled carbon nanotubes (SWCNTs) with high quality (IG/ID = 15.8) and low growth yield....
Synthesis and Characterization of a Composite of ZIF-8 and TiO2 NPs as a Photocatalyst Material for Water Treatment, M.Sc. Thesis Sharif University of Technology ; Dolati, Abolghasem ; Abachi, Parvin
During the past few years, hexavalent chromium (Cr(VI)) is of environmental concern due to its high toxicity and mobility. Therefore, removing it from industrial wastewater is of chief significance. In this research, efficient photocatalyst materials (xµLTiO2NPs@ZIF-8) for the reduction of Cr(VI) from water resources were firstly synthesized. This composite was prepared by an in situ method with zeolitic imidazolate framework-8 as the matrix. TiO2 and ZIF-8 were selected for their excellent stability in aqueous media, high photoactivity, non-toxicity, and high surface area. The structure of the as-synthesized materials was characterized by X-ray powder diffraction (XRD), scanning electron...
Zn-Ni Electrophosphating on galvanized steel using cathodic and anodic electrochemical methods, Article Surface and Coatings Technology ; January , 2015 ; 02578972 (ISSN) ; Afshar, A ; Aliabadi, A ; Sharif University of Technology
Electrophosphating is the novel method for accelerating the low temperature phosphating bath. This method can be performed as cathodic and anodic treatments. Both of them influence the coating deposition mechanism and therefore coating properties. In this study Zn-Ni electrophosphate coating was applied on galvanized steel using cathodic and anodic electrochemical methods. Microstructure, composition and corrosion resistance of coating were characterized by using a scanning electron microscopy, X-ray diffraction method and potentiodynamic polarization test respectively. The results of this study indicated that, by using cathodic method, compact phosphate coating with high corrosion...
Electrochemical determination of CdS band edges and semiconducting parameters, Article Bulletin of the Chemical Society of Japan ; Volume 88, Issue 6 , February , 2015 , Pages 814-820 ; 00092673 (ISSN) ; Jafarian, M ; Mahjani, M. G ; Gobal, F ; Heidaripour, A ; Sharif University of Technology
Chemical Society of Japan 2015
Cadmium sulfide (CdS) thin film was electrodeposited on indium tin oxide (ITO) by chronoamperometry. The SEM images showed that hexagonal sheets of CdS deposited on the ITO surface. The X-ray diffraction (XRD) analysis confirmed this structure for CdS crystals and the average of crystalline size and the lattice constant parameters are approximately 39.54 and a = 0.4136, c = 0.6696 nm respectively. Photo-electrochemical investigations were performed by cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) techniques. CdS band edges and density of states (DOS) were determined by CV technique. The band gap energy (E
bg) was measured...
Zn–Ni electrophosphating on galvanized steel using cathodic and anodic electrochemical methods, Article Surface and Coatings Technology ; Volume 306 , 2016 , Pages 497-505 ; 02578972 (ISSN) ; Afshar, A ; Aliabadi, A ; Sharif University of Technology
Elsevier B.V 2016
Electrophosphating is the novel method for accelerating the low temperature phosphating bath. This method can be performed as cathodic and anodic treatments. Both of them influence the coating deposition mechanism and therefore coating properties. In this study Zn–Ni electrophosphate coating was applied on galvanized steel using cathodic and anodic electrochemical methods. Microstructure, composition and corrosion resistance of coating were characterized by using a scanning electron microscopy, X-ray diffraction method and potentiodynamic polarization test respectively. The results of this study indicated that, by using cathodic method, compact phosphate coating with high corrosion...
In-situ electrochemical exfoliation of Highly Oriented Pyrolytic Graphite as a new substrate for electrodeposition of flower like nickel hydroxide: Application as a new high-performance supercapacitor, Article Electrochimica Acta ; Volume 206 , 2016 , Pages 317-327 ; 00134686 (ISSN) ; Mohammadi, R ; Amini, M. K ; Sharif University of Technology
Elsevier Ltd 2016
Demand for more efficient energy storage devices stimulates efforts to search and develop new materials and composites with promising properties. In this regard, composite materials, including carbonaceous materials and metal oxides have attracted a great attention due to better electrochemical performance as compared to their single material analogues. For the first time, herein, we report a new and simple procedure for preparing porous highly oriented pyrolytic graphite/nickel hydroxide composite (P-HOPG/Ni(OH)2) via a fast and simple two-step electrochemical method including potentiostatic routes. In the first step, a low anodic potential (2 V) was applied to pristine HOPG in 0.5 M H2SO4...
Effect of current density on electrochemical phosphating of stainless steel 316L, Article TMS 2009 - 138th Annual Meeting and Exhibition, San Francisco, CA, 15 February 2009 through 19 February 2009 ; Volume 3 , 2009 , Pages 613-620 ; 9780873397407 (ISBN) ; Afshar, A ; Sharif University of Technology
In this study two cation coating of calcium and zinc has been developed on stainless steel 316L by electrochemical method. Cathodic current used as an accelerator for phosphating process and the effects of current density on microstructure of the phospahted layer and the time needed for termination of the phosphating process has been evaluated by potential-time, SEM, EDS, etc. Results indicate that higher current densities in electrochemical phosphating will result in heavier phospahted layer with finer crystal size which in turn deteriorates the quality of the layer by its higher porosity. Chemical analysis of the layer reveals that using the electrochemical method for phosphating of...
Electrocrystallization of Ni nanocones from chloride-based bath using crystal modifier by electrochemical methods, Article Journal of Alloys and Compounds ; Volume 818 , 2020 ; Aliofkhazraei, M ; Dolati, A ; Rouhaghdam, A. S ; Sharif University of Technology
Elsevier Ltd 2020
The early stages of nucleation and growth of nanostructures can control the shape and final size of the fabricated nanostructure. Therefore, the study of the nucleation and growth mechanism of nanostructures is of great importance. The purpose of this study is to investigate the nucleation and growth mechanism of nickel nanocones from a chloride-based bath containing ethylene ammonium dichloride as a crystal modifier. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry tests were employed to investigate the nucleation and growth mechanism and also the mechanism of crystal modifier performance on the growth of nanocones. Electrochemical studies revealed...
Comparison of corrosion behavior between fusion cladded and explosive cladded Inconel 625/plain carbon steel bimetal plates, Article Materials and Design ; Volume 43 , January , 2013 , Pages 467-474 ; 02641275 (ISSN) ; Akbari Mousavi, S. A. A ; Madani Sani, F ; Sharif University of Technology
One of the main concerns in cladding Inconel 625 superalloy on desired substrates is deterioration of corrosion resistance due to cladding process. The present study aims to compare the effect of fusion cladding and explosive cladding procedures on corrosion behavior of Inconel 625 cladding on plain carbon steel as substrate. Also, an attempt has been made to investigate the role of load ratio and numbers of fusion layers in corrosion behavior of explosive and fusion cladding Inconel 625 respectively. In all cases, the cyclic polarization as an electrochemical method has been applied to assess the corrosion behavior. According to the obtained results, both cladding methods aggravate the...
Kinetic studies of glucose electrocatalytic oxidation on GC/Ni electrode, Article International Journal of Chemical Kinetics ; Volume 44, Issue 11 , 2012 , Pages 712-721 ; 05388066 (ISSN) ; Jafarian, M ; Forouzandeh, F ; Gobal, F ; Sharif University of Technology
Nickel-modified glassy carbon electrode (GC/Ni) prepared by galvanostatic deposition was used for the electrocatalytic oxidation of glucose in alkaline solutions where different electrochemical methods were employed. In cyclic voltammetry studies, in the presence of glucose an increase in the peak current of the oxidation of nickel hydroxide is followed by a decrease in the corresponding cathodic current. This suggests that the oxidation of glucose is being catalyzed through mediated electron transfer across the nickel hydroxide layer comprising nickel ions of various valence states. Under the chronoamperometric regime, the reaction followed a Cottrellian behavior and the diffusion...
Softening of bond stretching phonon mode in Ba 1-x K x BiO 3 superconductor, Article Journal of Superconductivity and Novel Magnetism ; Volume 23, Issue 7 , 2010 , Pages 1385-1389 ; 15571939 (ISSN) ; Kobayashi, J ; Tanaka, K ; Miyasaka, S ; Tajima, S ; Uchiyama, H ; Baron, A. Q. R ; Sharif University of Technology
Single crystals of Ba 1-x K x BiO 3 compound for different values of x (0 x 0.6) from insulator to superconducting region have been grown by electrochemical method. The crystals have been characterized by powder X-ray diffraction and Laue X-ray to determine the crystal structure, phases and potassium concentration. The phonon dispersion of the crystals in (100) direction has been investigated by high-resolution inelastic X-ray scattering. The phonon dispersion for low energy region is almost similar for all crystals measured in this study, while the higher energy modes shift to higher energy by increasing the potassium concentration. Anomalous softening of highest energy phonon has been...