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    Synthesis and Optical Properties of Cadmium Selenide Thin Films and Nanowires

    , M.Sc. Thesis Sharif University of Technology Kalhori, Hossein (Author) ; Iraji Zad, Azam (Supervisor) ; Dolati, Abolghasem (Supervisor)
    Abstract
    The interesting properties of metallic and semiconductor nanowires provide many applications in electronic and optoelectronic devices. In this project, we have synthesized Cu and CdSe nanowires using electrodeposition method. To adjust deposition bath conditions and characterize the structure of deposit first we prepared CdSe thin film on ITO substrates. The used solution was contained 0.1 M CdSO4+ 0.1 mM SeO2 in the acidic situation with pH=2.5. The best reduction potential was determined about -0.5 V. The XPS and XRD analyses showed that the ratio of cadmium to selenium in the films was 1:1 and the film’s structure is amorphous. Optical band gap of the cadmium selenide films was obtained... 

    , Ph.D. Dissertation Sharif University of Technology (Author) ; Aashuri, Hossein (Supervisor) ; Simchi, Abdolreza (Co-Advisor)
    Abstract
    We demonstrated efficient direct electron transfer from the enzyme glucose oxidase to vertically aligned gold nanorods with a diameter of ~160 nm and a length of ~2 μm that are covalently linkage to a 3-dimensional network of reduced graphene oxide nanosheets. The assembly can be prepared by a 2-step electrochemical procedure. This hybrid structure holds the enzyme in a favorable position while retaining its functionality that ultimately provides enhanced performance for enzymatic sensing of glucose without utilizing mediators. The nanorod assembly was applied to the voltammetric detection of glucose. Figures of merit include an electrochemical sensitivity of 12 µA⋅mM-1⋅cm-2 (obtained from... 

    Modification of Additively Manufactured Stainless Steel 316L Electrodes by Fe-Co-Ni Metal-Organic Framework and Gold Nanoparticle for Electrochemical Water Splitting and CO2 Reduction

    , M.Sc. Thesis Sharif University of Technology Mohammadnejad, Ali (Author) ; Simchi, Abdolreza (Supervisor)
    Abstract
    The processes of electrochemical water splitting and carbon dioxide reduction are among novel technologies that have gained attention for tackling climate change and global warming. Though, catalysts with fininancial justification for industrial utilization of these processes is still not available. In this study, a 3D-structured electrode of low-carbon 316 stainless steel, made by additive manufacturing, is modified with a trilayered metal-organic framework (MOF), with Iron, Cobalt, and Nickel metallic nodes and BDC-NH2 as the organic ligand, for water splitting. Also, the same steel electrode is modified with a single layered MOF, with Iron node and BDC-NH2 ligand, along with nanoparticles... 

    Al doped ZnO NanoStructures by Electrodeposition & Solvothermal for Dye Sensitized Solar Cells Application

    , M.Sc. Thesis Sharif University of Technology Ghahary, Raheleh (Author) ; Taghavinia, Nima (Supervisor)
    Abstract
    ZnO semiconductor has a wide band gap (3.3eV) and high electron mobility, making it a possible candidate for an effective structure-based Dye-sensitized solar cell (DSSC) semiconductor. Efficiency of DSSC based on ZnO is lower than TiO2 due to its low chemical satability. It is well known that the energy conversion efficiency of DSSC depends on the electron transport in the photoelectrode so in this investigation we fabricated high transport photoelectrode by doping Al in ZnO nanostructures. DSSC based on Al doped and undoped ZnO nanosheet synthesized by electrochemical deposition. Current density-voltage (J-V) characterizations indicate that Al-doping in ZnO crystal structure increases... 

    Removal of Micropollutants from Wastewater Using an Electrochemical Biomembrane Reactor

    , M.Sc. Thesis Sharif University of Technology Abbasi, Pezhman (Author) ; Ghasemian, Saloumeh (Supervisor) ; Ghobadinejad, Zahra (Co-Supervisor) ; Hamzehlouyan, Tayebeh (Co-Supervisor)
    Abstract
    One of the major environmental problems in recent years is the presence of micropollutants that cause many problems for the environment and living organisms. Diclofenac is one of the micropollutants and endocrine disruptors. Conventional treatment methods do not have the ability to effectively remove pharmaceutical pollutants and micro-pollutants, and finding a suitable approach to remove these pollutants is of great importance. In recent years, biological methods such as the use of enzymes and molds have received attention, but due to the relative removal of pollutants, these methods have been combined with membrane technology to improve the level of pollutant removal and increase the... 

    Synthesis of Palladium Nanowires for Hydrogen Gas Sensor by Field Ionization

    , M.Sc. Thesis Sharif University of Technology dolatkhah, Naeme (Author) ; Irajizad, Azam (Supervisor)
    Abstract
    The interesting properties of metallic nanowires provide many applications in electronic sensors. In this project, we have synthesized Pd nanowires using electrodeposition method. These nanowires are useful for hydrogen sensors by measuring field ionization current in gas. In this project, Pd nanowires were synthesized by electrochemical deposition method in PCT template with 100 nm pore size. The used solution was contained 2mM PdCl2 + 0.1M HCl. The best reduction potential was determined about -0.2V and the best time for synthesizing nanowires was 7 minutes. Chronoampermetric diagrams showed four steps, capacitive current, growth in the holes, reaching to the surface of PCT and the growth... 

    Controlled engineering of WS2 nanosheets-CdS nanoparticle heterojunction with enhanced photoelectrochemical activity

    , Article Solar Energy Materials and Solar Cells ; Volume 141 , 2015 , Pages 260-269 ; 09270248 (ISSN) Zirak, M ; Zhao, M ; Moradlou, O ; Samadi, M ; Sarikhani, N ; Wang, Q ; Zhang, H. L ; Moshfegh, A. Z ; Sharif University of Technology
    Elsevier  2015
    Abstract
    Abstract We report the well-controlled preparation of WS2 nanosheets-CdS nanoparticle heterojunction for photoelectrochemical (PEC) water splitting application. The WS2 nanosheets with an average thickness of ~5 nm and lateral dimensions of ~200 nm were synthesized via liquid phase exfoliation of bulk WS2 in water/ethanol solution, followed by deposition onto ITO substrate via electrophoretic method. CdS nanoparticles were grown via facile successive ion layer absorption and reaction (SILAR) method. Using these two well-controlled methods, CdS/WS2/ITO and WS2/CdS/ITO systems were fabricated. The loading of WS2 nanosheets was... 

    Constructing BiVO4/Graphene/TiO2 nanocomposite photoanode for photoelectrochemical conversion applications

    , Article Journal of Electroanalytical Chemistry ; Volume 763 , 2016 , Pages 1-9 ; 15726657 (ISSN) Yousefzadeh, S ; Faraji, M ; Moshfegh, A. Z ; Sharif University of Technology
    Elsevier B.V  2016
    Abstract
    BiVO4/Graphene/TiO2 as a novel nanocomposite photoanode was designed, synthesized and characterized for photoelectrochemical application. BiVO4/Graphene nanocomposite was initially synthesized by photocatalytic process and then, BiVO4/Graphene/TiO2 nanocomposite thin film was prepared by deposition of the BiVO4/Graphene solution onto the surface of sol-gel derived TiO2 thin film. Morphology, crystal structure, surface chemical composition and optical properties of the synthesized BiVO4/Graphene/TiO2 nanocomposite thin film were characterized and compared with the BiVO4/Graphene and pure TiO2 samples. Observations of scanning electron microscopy (SEM) images revealed that the surface of the... 

    Enhanced photoelectrochemical activity of Ce doped ZnO nanocomposite thin films under visible light

    , Article Journal of Electroanalytical Chemistry ; Volume 661, Issue 1 , 2011 , Pages 106-112 ; 15726657 (ISSN) Yousefi, M ; Amiri, M ; Azimirad, R ; Moshfegh, A. Z ; Sharif University of Technology
    Abstract
    Ce-doped ZnO and pure ZnO nanocomposite thin films with different Ce/Zn ratios (0, 2, 5, 10, 15, 20, and 30 at.%) have been prepared by sol-gel method at optimum annealing temperature of 500 °C. The synthesized samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis spectrophotometry. According to our XPS data analysis, there are three major metal ions namely Ce3+, Ce4+ and Zn 2+ that coexist on the surface. The XRD measurements indicate that the ZnO thin films have a hexagonal wurtzite structure, and CeO2 crystallites formed in the Ce-doped ZnO nanocomposite thin films. Photoelectrochemical property of the samples was studied by three... 

    Size and geometry of multielectrode arrays determine the efficiency of electrical interaction with neurons through double-layer capacitance

    , Article IEEE Sensors Journal ; Volume 19, Issue 8 , 2019 , Pages 2829-2836 ; 1530437X (ISSN) Vafaiee, M ; Mohammadpour, R ; Vossoughi, M ; Sasanpour, P ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    Multielectrode array (MEA) structures are the vital parts in the interface between neural structures and external electronic circuits, both in excitation and detection. As a transducer, the performance of electrodes has direct effect on the quality of the recorded neural signal, as well as induced charge density during the stimulation in neural prosthesis. The size and geometry of the electrode structure have distinct effect on the performance of electrodes accordingly. In this paper, the effect of size and geometry of the electrodes has been investigated in their performance and the impedimetric features of the fabricated electrodes with different structures have been studied. Based on the... 

    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
    Abstract
    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... 

    Novel visible light photocatalytic and photoelectrochemical (PEC) activity of carbon-doped zinc oxide/reduced graphene oxide: supercritical methanol synthesis with enhanced photocorrosion suppression

    , Article Journal of Alloys and Compounds ; Volume 723 , 2017 , Pages 1001-1010 ; 09258388 (ISSN) Tayyebi, A ; Soltani, T ; Lee, B. K ; Outokesh, M ; Tayebi, M ; Sharif University of Technology
    Abstract
    Carbon-doped zinc oxide/reduced graphene oxide (C-ZnO/rGO) was prepared by a facile one-pot supercritical methanol method. The synthesized C-ZnO/rGO nanocomposite with flower-like ZnO micro-rods (MRs) synergistically inherited all the advantages of carbon doping and rGO heterojunction and exhibited high photocatalytic activity for the photodegradation of methyl orange (MO) under visible light. The x-ray diffraction (XRD) results indicated that in presence of GO, a new carbon-doped phase was formed at the high temperature and pressure of supercritical methanol. The x-ray photoelectron spectroscopy (XPS) at low binding energies demonstrated that the valence band of C-ZnO-rGO is up-shifted by... 

    Horseradish peroxidase immobilization on amine functionalized carbon nanotubes: direct electrochemistry and bioelectrocatalysis

    , Article Progress in Reaction Kinetics and Mechanism ; Volume 37, Number 2 , 2012 , pp. 161-172 Tasviri, M. (Mahboubeh) ; Ghourchian, H. (Hedayatollah) ; Gholami, M. R. (Mohammad Reza) ; Rafieepour, H. A. (Hossain Ali) ; Sharif University of Technology
    Abstract
    Horseradish peroxidase (HRP) was successfully immobilized on amine functionalized TiO2-coated multiwalled carbon nanotubes (NH2 – TiO2 – CNTs) by a convenient and efficient method. Electrochemical impedance spectroscopy, cyclic voltammetry and amperometry were applied to characterize the HRP/NH2 – TiO2 – CNT nano-composite. These techniques showed that the NH2 – TiO2 – CNTs greatly enhance the electron transfer between HRP and the modified electrode. Owing to the redox reaction of the electroactive centre of HRP, the HRP = NH2 – TiO2 – CNTs modified electrode exhibited a pair of quasi-reversible peaks with a peak-to-peak separation (ΔEp) of 70.6 mV and a formal potential (E 0′) of 367.65 mV... 

    Ionic liquid/graphene oxide as a nanocomposite for improving the direct electrochemistry and electrocatalytic activity of glucose oxidase

    , Article Journal of Solid State Electrochemistry ; Vol. 17, Issue 1 , January , 2013 , pp 183-189 ; ISSN: 1432-8488 Tasviri, M (Mahboubeh) ; Ghasemi, S. (Shahnaz) ; Ghourchian, H. (Hedayatollah) ; Gholami, M. R. (Mohammad Reza) ; Sharif University of Technology
    Abstract
    By combination of 1-ethyl-3-methyl immidazolium ethyl sulfate as a typical room temperature ionic liquid (IL) and graphene oxide (GO) nanosheets, a nanocomposite was introduced for improving the direct electrochemistry and electrocatalytic activity of glucose oxidase (GOx). The enzyme on the IL–GO-modified glassy carbon electrode exhibited a quasireversible cyclic voltammogram corresponding to the flavine adenine dinucleotide/FADH2 redox prosthetic group of GOx. At the scan rate of 100 mV s−1, the enzyme showed a peak-to-peak potential separation of 82 mV and the formal potential of −463 mV (vs Ag/AgCl in 0.1 M phosphate buffer solution, pH 7.0). The kinetic parameters of the charge transfer... 

    Ionic liquid/graphene oxide as a nanocomposite for improving the direct electrochemistry and electrocatalytic activity of glucose oxidase

    , Article Journal of Solid State Electrochemistry ; Volume 17, Issue 1 , January , 2013 , Pages 183-189 ; 14328488 (ISSN) Tasviri, M ; Ghasemi, S ; Ghourchian, H ; Gholami, M. R ; Sharif University of Technology
    2013
    Abstract
    By combination of 1-ethyl-3-methyl immidazolium ethyl sulfate as a typical room temperature ionic liquid (IL) and graphene oxide (GO) nanosheets, a nanocomposite was introduced for improving the direct electrochemistry and electrocatalytic activity of glucose oxidase (GOx). The enzyme on the IL-GO-modified glassy carbon electrode exhibited a quasireversible cyclic voltammogram corresponding to the flavine adenine dinucleotide/FADH2 redox prosthetic group of GOx. At the scan rate of 100 mV s-1, the enzyme showed a peak-to-peak potential separation of 82 mV and the formal potential of -463 mV (vs Ag/AgCl in 0.1 M phosphate buffer solution, pH 7.0). The kinetic parameters of the charge transfer... 

    Horseradish peroxidase immobilization on amine functionalized carbon nanotubes: Direct electrochemistry and bioelectrocatalysis

    , Article Progress in Reaction Kinetics and Mechanism ; Volume 37, Issue 2 , May , 2012 , Pages 161-172 ; 14686783 (ISSN) Tasviri, M ; Ghourchian, H ; Gholami, M. R ; Rafiee Pour, H. A ; Sharif University of Technology
    2012
    Abstract
    Horseradish peroxidase (HRP) was successfully immobilized on amine functionalized TiO 2-coated multiwalled carbon nanotubes (NH 2-TiO 2-CNTs) by a convenient and efficient method. Electrochemical impedance spectroscopy, cyclic voltammetry and amperometry were applied to characterize the HRP/NH 2-TiO 2-CNT nano-composite. These techniques showed that the NH 2-TiO 2-CNTs greatly enhance the electron transfer between HRP and the modified electrode. Owing to the redox reaction of the electroactive centre of HRP, the HRP/NH 2-TiO 2-CNTs modified electrode exhibited a pair of quasi-reversible peaks with a peak-to-peak separation (ΔE p) of 70.6mV and a formal potential (E 0′) of -367.65mV (versus... 

    Amine functionalized TiO2 coated on carbon nanotube as a nanomaterial for direct electrochemistry of glucose oxidase and glucose biosensing

    , Article Journal of Molecular Catalysis B: Enzymatic ; Volume 68, Issue 2 , 2011 , Pages 206-210 ; 13811177 (ISSN) Tasviri, M ; Rafiee Pour, H. A ; Ghourchian, H ; Gholami, M. R ; Sharif University of Technology
    Abstract
    A nano-composite material consisting of amine functionalized TiO 2-coated carbon nanotubes was prepared and used for glucose oxidase (GOx) absorption. The GOx bearing nanomaterial was fixed on a glassy carbon electrode to construct a novel biosensor for glucose determination. The direct electrochemistry of immobilized GOx and its electron transfer parameters at the modified glassy carbon electrode were reported. The apparent heterogeneous electron transfer rate constant (ks) of GOx was estimated to be 3.5 s-1, which is higher than those reported previously. Amperometric detection of glucose resulted in a rapid (3 s) and stable response in the linear concentration range from 1.8 to 266 μM.... 

    A novel screen-printed TiO2 photoelectrochemical sensor for direct determination and reduction of hexavalent chromium

    , Article Electrochemistry Communications ; Volume 61 , 2015 , Pages 110-113 ; 13882481 (ISSN) Siavash Moakhar, R ; Goh, G. K. L ; Dolati, A ; Ghorbani, M ; Sharif University of Technology
    Elsevier Inc  2015
    Abstract
    A novel and simple photoelectrochemical (PEC) sensor to detect Cr(VI) based on screen-printed TiO2 modified with gold nanoparticles is presented. The proposed PEC sensor showed a very low detection limit (S/N = 3) of 0.004 μM, over a wide linear concentration range from 0.01 μM to 100 μM with a high sensitivity of 11.88 μA.μM-1 Cr(VI). Results also indicated good anti-interference and superb recovery in natural media application for Cr(VI) sensing  

    Sunlight driven photoelectrochemical light-to-electricity conversion of screen-printed surface nanostructured TiO2 decorated with plasmonic Au nanoparticles

    , Article Electrochimica Acta ; Volume 219 , 2016 , Pages 386-393 ; 00134686 (ISSN) Siavash Moakhar, R ; Masudy Panah, S ; Jalali, M ; Liang Goh, G. K ; Dolati, A ; Ghorbani, M ; Riahi Noori, N ; Sharif University of Technology
    Elsevier Ltd  2016
    Abstract
    In this paper, we report a promising sunlight-driven screen-printed TiO2 porous nanorods (PNR) photoanode decorated with Au plasmonic nanostructures for photoelectrochemical (PEC) light-to-electricity conversion. Fabricated photoanodes were characterized using field emission scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive spectroscopy, X-Ray diffraction analysis, X-ray photoelectron spectroscopy, N2 adsorption-desorption isotherms, UV–vis spectroscopy and electrochemical impedance spectroscopy in detail. The Au-PNR-TiO2 photoanode demonstrates superior PEC activities both under simulated sunlight and visible light irradiation. Interestingly,... 

    Enhancement in solar driven water splitting by Au–Pd nanoparticle decoration of electrochemically grown ZnO nanorods

    , Article Journal of Applied Electrochemistry ; Volume 46, Issue 8 , 2016 , Pages 819-827 ; 0021891X (ISSN) Siavash Moakhar, R ; Kushwaha, A ; Jalali, M ; Goh, G. K. L ; Dolati, A ; Ghorbani, M ; Sharif University of Technology
    Springer Netherlands 
    Abstract
    Oriented ZnO nanorods were grown directly on fluorine doped tin oxide substrates by a single bath electrodeposition process. A pulse potential at the beginning of growth improved the density and orientation of the nanorods. Pulse potential grown ZnO nanorod films showed better harvesting of visible light and enhanced the light driven water splitting performance in comparison to nanorods grown without any pulse potential. To further improve the water splitting activity, the nanorods were decorated with gold–palladium nanoparticles by sputtering. This caused visible light absorption to increase due to a plasmonic effect and the photoelectrochemical water splitting performance to further...