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    Electrochemical and Photocatalytic Behaviour of V&S Doped Titania Produced with Plasma Electrolytic Oxidation

    , M.Sc. Thesis Sharif University of Technology Ahmadzadeh, Mohammad (Author) ; Ghorbani, Mohammad (Supervisor)
    Plasma Electrolytic Oxidation is a new and promising method for synthesis of oxide layers and coatings on light metals such as titanium and aluminum. This method is a fast, easy and economicalway to produce TiO2 layers on Ti substrate. Photocatalytic properties of TiO2 can be improved with doping of other elements such as metals and non-metals by expanding its band gap which is in UV area of light spectrum in to visible area.Photocatalytic properties of TiO2 is also dependent on surface area and grain size, oxide layers which has been produced with PEO process has a high surface area due to its porosity. Voltage, electrolyte and additives concentration are among parameters which can affect... 

    Synthesis of Carbon Nanostructure-Metal Nanoparticles Composites and Investigate their Application as a Modifier in Electrochemical Mesurments

    , Ph.D. Dissertation Sharif University of Technology Hosseininassab, Niloufar (Author) ; Shahrokhian, Saeed (Supervisor)
    In the first part, metallic nanoparticles were synthesized on the different carbon nanostructers platform such as nanodiamond and graphene sheet using electrochemical and chemical methods. The prepared composite film were characterized by electron microscopy, spectroscopy and electrochemical techniques. The synthesized nanocomposite were applied as a modifier in order to prepare electrochemical sensors for determination trace amount of important pharmaceutical and biological compounds.In the first work, Nanodiamond-graphite (NDG) decorated with Ag nanoparticles (AgNPs-NDG) was synthesized with chemical method. The surface morphology and the nature of the composite were investigated. The... 

    Electrochemical Hydrogen Generation Using Metal Organic Frameworks Derived Catalysts

    , M.Sc. Thesis Sharif University of Technology Koohdareh, Amir Reza (Author) ; Gholami, Mohamad Reza (Supervisor)
    In recent years, the widespread investigation on multi-transition metal oxides that with two or more transition metal oxides, have been increased rapidly for electrochemical application due to low cost, high conductivity and good electrochemical performance other than single metal oxides. In this project, CuCo2O4 nanoparticles were firstly fabricated by decomposing of CuCo-MOF as the template. The as prepared samples were used to synthesis a new nanocomposite of MoS2 and CuCo2O4. The best ratio of the two component were optimized to prepare the best electrocatalyst for Hydrogen evolution reaction (HER). The structure of prepared nanocomposite were investigated by various techniques such as... 

    Electrochemical behavior of S-doped nanostructured TiO2 layer synthesized with PEO process for photocatalytic applications

    , Article Advanced Materials Research ; Volume 829 , 2014 , Pages 487-491 ; ISSN: 10226680 ; ISBN: 9783037859070 Ahmadzadeh, M ; Ghorbani, M ; Sharif University of Technology
    Sulfur doped and pure micro-nanoporous TiO2 film were synthesized with PEO method to produce a film with a high surface area for photocatalysis applications. The effect of applied voltage and electrolyte concentration on the microstructure and photocatalytic properties of the prepared layer were investigated via SEM, XRD, EIS and DRS studies. Electrochemical Impedance Spectroscopy (EIS) was carried out in order to determine the corrosion and electrochemical properties of the produced layer. It was found that although the barrier layer resistance decreases with the voltage, the layers porosity and consequently the surface area increases. Finally the XRD and DRS spectrums were correlated with... 

    TiO2 surface nanostructuring for improved dye loading and light scattering in double-layered screen-printed dye-sensitized solar cells

    , Article Journal of Applied Electrochemistry ; Volume 45, Issue 8 , 2015 , Pages 831-838 ; 0021891X (ISSN) Jalali, M ; Moakhar, R. S ; Kushwaha, A ; Goh, G. K. L ; Sadrnezhaad, S. K ; Riahi Noori, N ; Sharif University of Technology
    Kluwer Academic Publishers  2015
    Abstract: Surface-nanostructured TiO2 nanorods were synthesized hydrothermally at 180 °C. Such nanorods have ‘crack-like’ surfaces that resemble burnt charcoal. Compared to nanorods with relatively smoother surfaces, the charcoal-like nanorods have higher-specific surface areas. By using the nanorods as a light-scattering layer in double-layered dye-sensitized solar cells, the cells based on the charcoal-like nanorods have 20 % higher dye loading and also higher diffuse reflectance compared with cells utilizing ‘smooth’ nanorods. The efficiency of a screen-printed double-layer dye-sensitized solar cell based on the charcoal-like nanorods is higher at 7.29 %. Electrochemical... 

    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) Miandari, S ; 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 (Ebg) was measured... 

    Multistep reduction of oxygen on polycrystalline silver in alkaline solution

    , Article Cuihua Xuebao/Chinese Journal of Catalysis ; Volume 31, Issue 5 , 2010 , Pages 541-546 ; 02539837 (ISSN) Jafarian, M ; Gobal, F ; Mahjani, M. G ; Hosseini Aliabadi, M ; Sharif University of Technology
    Oxygen reduction on a polycrystalline silver electrode was studied by cyclic voltammetry and electrochemical impedance spectroscopy. The reaction occurred by a two-electron pathway. The steps in the mechanism were observed in the cyclic voltammograms recorded with different scan rates. The intermediates formed in the steps were detected by electrochemical impedance spectroscopy  

    The pH effects on the capacitive behavior of nanostructured molybdenum oxide

    , Article Journal of Solid State Electrochemistry ; Volume 14, Issue 4 , 2010 , Pages 681-686 ; 14328488 (ISSN) Farsi, H ; Gobal, F ; Raissi, H ; Moghiminia, S ; Sharif University of Technology
    Nanostructured molybdenum oxide having a particle size in the range of 30-80 nm was prepared by potentiodynamic electrodeposition method, and the effects of H2SO4 concentration on its capacitive behavior were studied by cyclic voltammetry, galvanostatic discharge, and electrochemical impedance spectroscopy. Poor to fair capacitive behaviors were witnessed depending on the electrolyte concentration and conditions of charge/discharge. Increasing acid concentration to 0.02 M had favorable effect, while beyond that, the effect was detrimental. Capacitance around 600 F g-1 was recorded in the potential range of 0 to -0.55 V vs. Ag/AgCl  

    Impact of chromium doping on physical, optical, electronic and photovoltaic properties of nanoparticle TiO2 photoanodes in dye-sensitized solar cells

    , Article New Journal of Chemistry ; Volume 41, Issue 23 , 2017 , Pages 14516-14527 ; 11440546 (ISSN) Vafaei, M ; Mohammadi, M. R ; Sharif University of Technology
    Royal Society of Chemistry  2017
    Herein, we report the impact of chromium doping on the physical properties, electronic band structure and photovoltaic characteristics of their corresponding devices based on dye-sensitized solar cells (DSCs). Different DSCs with various compositions of the photoanode electrodes are fabricated to study their optical, structural, conduction band edge, donor density, depth of trap states and photoelectrochemical properties using X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), field-emission scanning electron microscopy (FE-SEM), Mott-Schottky capacitance analysis, chemical capacitance and electrochemical impedance spectroscopy (EIS) measurements. For such studies, the Cr-doped... 

    Electric field enhanced synthesis of copper hydroxide nanostructures for supercapacitor application

    , Article Nano ; Volume 12, Issue 1 , 2017 ; 17932920 (ISSN) Sepahvand, S ; Ghasemi, S ; Sanaee, Z ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2017
    Electric field enhanced approach has been used to synthesize different copper hydroxide morphologies as high-performance supercapacitors electrode materials. Employing this efficient, simple and low cost method, various shapes such as rod, flower and cube with an average grain size of 30nm to 1μm were obtained on the copper substrate. The results revealed that applied electric field considerably accelerates the formation time of nanostructures from several days to close to 1min, where some of the desired nanostructures were obtained even in 1s. The electrochemical properties of different morphologies were compared using cyclic voltammograms and charge/discharge tests and electrochemical... 

    Nanoporous gold as a suitable substrate for preparation of a new sensitive electrochemical aptasensor for detection of salmonella typhimurium

    , Article Sensors and Actuators, B: Chemical ; Volume 255 , 2018 , Pages 1536-1544 ; 09254005 (ISSN) Ranjbar, S ; Shahrokhian, S ; Nurmohammadi, F ; Sharif University of Technology
    Elsevier B.V  2018
    Nowadays, achievement to easy, fast, reliable and cost-effective techniques and tools is one of the most important challenges in detection of microorganisms. Salmonella typhimurium is one of the most important pathogenic bacteria that affect the human health and environmental infections. In this work we report a new, stable, biocompatible and cost-effective platform for construction of an aptasensor based on nanoporous gold (NPG) for detection of S. typhimurium. Nanoporous gold is electrochemically synthesized using Au-Cu alloy at the surface of Au/GCE. Thiol functionalized aptamer is used for effective linking to the surface of NPG/Au/GCE via self-assemble monolayers (SAMs) formation.... 

    Development of a sensitive diagnostic device based on zeolitic imidazolate frameworks-8 using ferrocene-graphene oxide as electroactive indicator for pseudomonas aeruginosa detection

    , Article ACS Sustainable Chemistry and Engineering ; Volume 7, Issue 15 , 2019 , Pages 12760-12769 ; 21680485 (ISSN) Shahrokhian, S ; Ranjbar, S ; Sharif University of Technology
    American Chemical Society  2019
    Since Gram-negative bacteria have a predominant role in nosocomial infections, there are high demands to develop a fast and sensitive method for diagnosis of bacteria in clinical samples. To address this challenge, we designed a novel electrochemical biosensor based on aptamers immobilized in engineered zeolitic imidazolate Framework-8 (ZIFs-8) via EDC-NHS chemistry. Cyclic voltammetry and electrochemical impedance spectroscopy techniques were conducted to monitor the electrochemical characterization. With respect to unique π-πinteractions between aptamer and graphene oxide (GO), the differential pulse voltammetry technique was applied with ferrocene-graphene oxide (Fc-GO) as an... 

    Electrocrystallization of Ni nanocones from chloride-based bath using crystal modifier by electrochemical methods

    , Article Journal of Alloys and Compounds ; Volume 818 , 2020 Barati Darband, G ; 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... 

    Epoxy nanocomposite coatings with enhanced dual active/barrier behavior containing graphene-based carbon hollow spheres as corrosion inhibitor nanoreservoirs

    , Article Corrosion Science ; Volume 185 , 2021 ; 0010938X (ISSN) Haddadi, S. A ; Ramazani Saadatabadi, A ; Mahdavian, M ; Arjmand, M ; Sharif University of Technology
    Elsevier Ltd  2021
    Graphene-based carbon hollow spheres (CHSs) fabrication, doped with 2-mercaptobenzimidazole (MBI) was successfully done in previous work. The active/barrier corrosion protection performance (CPP) of epoxy coatings was evaluated using salt spray test, electrochemical impedance spectroscopy (EIS), and scanning vibrating electrode technique (SVET). Results proved the active/barrier CPP enhancement of epoxy coatings in the presence of 3 wt. % MBI@CHSs. While the presence of MBI and empty CHSs in epoxy coatings did not further improve the active performance. An improvement in the adhesion loss of the epoxy coating, ca. 58 %, was observed in the presence of 3 wt. % MBI@CHSs. © 2021  

    DNA impedance biosensor for detection of cancer, TP53 gene mutation, based on gold nanoparticles/aligned carbon nanotubes modified electrode

    , Article Analytica Chimica Acta ; Vol. 836, issue , July , 2014 , p. 34-44 ; ISSN: 00032670 Fayazfar, H ; Afshar, A ; Dolati, M ; Dolati, A ; Sharif University of Technology
    For the first time, a new platform based on electrochemical growth of Au nanoparticles on aligned multi-walled carbon nanotubes (A-MWCNT) was developed for sensitive lable-free DNA detection of the TP53 gene mutation, one of the most popular genes in cancer research. Electrochemical impedance spectroscopy (EIS) was used to monitor the sequence-specific DNA hybridization events related to TP53 gene. Compared to the bare Ta or MWCNT/Ta electrodes, the synergistic interactions of vertically aligned MWCNT array and gold nanoparticles at modified electrode could improve the density of the probe DNA attachment and resulting the sensitivity of the DNA sensor greatly. Using EIS, over the extended... 

    Modification of glassy carbon electrode with a bilayer of multiwalled carbon nanotube/tiron-doped polypyrrole: Application to sensitive voltammetric determination of acyclovir

    , Article Materials Science and Engineering C ; Volume 53 , 2015 , Pages 134-141 ; 09284931 (ISSN) Shahrokhian, S ; Azimzadeh, M ; Amini, M. K ; Sharif University of Technology
    Elsevier Ltd  2015
    A novel voltammetric sensor based on glassy carbon electrode (GCE) modified with a thin film of multi-walled carbon nanotubes (MWCNTs) coated with an electropolymerized layer of tiron-doped polypyrrole was developed and the resulting electrode was applied for the determination of acyclovir (ACV). The surface morphology and property of the modified electrode were characterized by field emission scanning electron microscopy and electrochemical impedance spectroscopy techniques. The electrochemical performance of the modified electrode was investigated by means of linear sweep voltammetry (LSV). The effect of several experimental variables, such as pH of the supporting electrolyte, drop size of... 

    In situ two-step preparation of 3D NiCo-BTC MOFs on a glassy carbon electrode and a graphitic screen printed electrode as nonenzymatic glucose-sensing platforms

    , Article ACS Sustainable Chemistry and Engineering ; Volume 8, Issue 38 , 2020 , Pages 14340-14352 Ezzati, M ; Shahrokhian, S ; Hosseini, H ; Sharif University of Technology
    American Chemical Society  2020
    In the present study, a rational two-step strategy is employed for the green, fast, very simple, and highly controllable synthesis of the bimetallic nickel-cobalt-based metal-organic frameworks (MOFs) on glassy carbon substrates by in situ transformation of nickel-cobalt-layered double hydroxide nanosheet (NiCo-LDHs NSs) intermediates into nickel-cobalt-benzene tricarboxylic acid MOFs (E-NiCo-BTC MOFs). The structural characteristics of the electrode materials in each step were investigated via Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, elemental mapping, field emission scanning electron microscopy, and transmittance electron microscopy.... 

    Design of Doped TiO2 Dye-sensitized Solar Cells with Different Arrangement Modes of Photoanode Electrodes

    , M.Sc. Thesis Sharif University of Technology Vafaei, Maral (Author) ; Mohammadi, Mohammad Reza (Supervisor)
    In this thesis, pure –known as T- and chromium doped titanium dioxide nanoparticles –known as -CTx- with different dopant atomic ratio (0.1 to 5 %at.) were synthesized using a facile, fast and efficient method. FESEM and XRD studies showed no morphologic and structural change via Cr doping of nanoparticles (size in the range of 20-30 nm). However, according to DRS analysis, Cr intrusion in TiO2 crystal structure, drastically reduced band gap energy of pure TiO2 from 3.14 eV to 1.81 eV for CT3 powder and improved absorption range of UV-Vis spectrum. Mott-Schottky plots indicated that, Cr doping, caused reduction in donor density of TiO2 and an upward shift in the conduction band edge.... 

    Investigation of Electrocatalytic Activity of Metal-based Nanocomposites in the Reaction of Carbon Dioxide Reduction

    , M.Sc. Thesis Sharif University of Technology Hatami, Homayoun (Author) ; Bastani, Darioush (Supervisor) ; Taherinia, Davood (Supervisor)
    Emissions of carbon dioxide (CO2) from fossil fuels are a potential issue for the global climate. One way to meet this challenge is to electrochemically convert CO2 molecules to reduced carbon species such as formates, alcohols, hydrocarbons, etc., which is a difficult process due to the poor kinetics of CO2 reduction. Therefore, the use of catalysts, while preventing undesirable side reactions, can also play an important role in reducing CO2. In this study, a two-step synthesis of CuS (1, 5, 12, 24 hr) @ Cu-MOF has been reported as an advanced electrocatalyst for CO2 reduction in neutral pH environments. Bismuth has been used to improve the electrocatalytic properties of the samples. Bi-CuS... 

    Synthesis, Characterization and Investigation of Electrocatalytic Activity of Nanoparticle/Cerium Oxide Composites in Oxygen Evolution and Reduction Reactions

    , M.Sc. Thesis Sharif University of Technology Moravvej, Heydar (Author) ; Taherinia, Davood (Supervisor)
    The sluggish kinetics of oxygen evolution and reduction on the surface of electrodes is a major problem for the widespread use of devices that are based on sustainable, renewable and clean technologies, such as fuel cells and metal–air batteries. Therefore, the development of efficient and cost–effective materials for the oxygen evolution (OER: Oxygen Evolution Reaction) and reduction reactions (ORR: Oxygen Reduction Reaction) is highly desirable. In recent years, Metal–organic frameworks (MOFs) and their derivatives, have drawn considerable attention as potential catalysts and electrocatalyst due to their high surface area and porous structure. In this study, cerium (IV) oxide was...