Search for: hydrogen-evolution
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    A review of 2D-based counter electrodes applied in solar-assisted devices

    , Article Coordination Chemistry Reviews ; Volume 324 , 2016 , Pages 54-81 ; 00108545 (ISSN) Irani, R ; Naseri, N ; Beke, S ; Sharif University of Technology
    Elsevier  2016
    The alarming energy and environmental crisis of our modern era necessitates scientists to propose alternatives to replace the scarce and harmful fossil fuels. The Sun, as a free, and abundant clean energy resource, presents a motivation for researchers to convert the sunlight to electrical power and store the H2 as an energy carrier by developing solar cells as well as water splitting devices, respectively. One of the fundamental parts of a solar energy convertor (solar cell/photoelectrochemical device), where the reduction reaction occurs, is the counter electrode (CE); the CE is commonly based on rare Pt. It is critical to substitute costly CEs with efficient, low-cost replacements, which... 

    Manipulation of Electronic Structure in Boron Nitride Nanosheets to Improve Catalytic and Photocatalytic Properties

    , M.Sc. Thesis Sharif University of Technology Hemmati, Amir (Author) ; Simchi, Abdolreza (Supervisor)
    The variety of 2D materials and their wide range of properties, as well as numerous methods to manipulate them, have made this class of materials among prominent candidates for the future of the energy industry. Among the means available to tailor nanomaterials performance for such applications, introducing dopants and the creation of heteroatom-doped structures are of great interest. In this study, mixtures of urea, boric acid, and graphene oxide, as cheap and available precursors, were used to synthesize C-doped h-BN nanosheets. After the implementation of TGA/DSC to select a suitable calcination temperature of 950 C°, the samples were successfully synthesized with relatively precise... 

    The investigation of the kinetics and mechanism of hydrogen evolution reaction on tin

    , Article International Journal of Hydrogen Energy ; Volume 32, Issue 12 , 2007 , Pages 1755-1761 ; 03603199 (ISSN) Azizi, O ; Jafarian, M ; Gobal, F ; Heli, H ; Mahjani, M. G ; Sharif University of Technology
    The mechanism and kinetics of the hydrogen evolution reaction (HER) on tin electrode in 0.1 M H2SO4 solution were studied using the methods of steady-state polarization and electrochemical impedance spectroscopy. The simulation of the data obtained from these two methods, using nonlinear fitting procedure allowed us to determine the rate constants of Volmer, Heyrovsky and Tafel steps associated with the mentioned reaction. The kinetic results indicate that HER mechanism at low negative potentials is a serial combination of Volmer step and parallel Tafel and Heyrovsky steps. At high negative potentials where the hydrogen coverage reaches its limiting value, a Tafel line with the slope of -... 

    Hydrogen electrosorption on TiHg alloy in acidic solution

    , Article Journal of Alloys and Compounds ; Volume 432, Issue 1-2 , 2007 , Pages 74-80 ; 09258388 (ISSN) Jafarian, M ; Azizi, O ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
    Hydrogen evolution and electrosorption on/in TiHg alloy have been investigated in acidic solution using cyclic voltammetry, open circuit potential transient, steady-state polarization, chronopotentiometry and electrochemical impedance measurements. Comparison has been made with pure Ti. Cyclic voltammetry and open circuit potential measurements show that hydrogen absorption into the electrode material occurs during proton discharge. The steady-state polarization curves in the course of positive and negative potential scans illustrate that the formation of absorbed hydrogen slightly improves the electrocatalytic properties of the electrode. The hydrogen diffusion coefficient into the bulk of... 

    Pulse Reverse Electrodeposition of Ni-Mo Alloy on Cu

    , M.Sc. Thesis Sharif University of Technology Surani Yancheshmeh, Hooman (Author) ; Ghorbani, Mohammad (Supervisor)
    Alloy coating of nickel - molybdenum with 20-25 wt% Mo, exhibits excellent protective properties against corrosion in different corrosive environments, therefore it has received much attention. In comparison with Ni coatings, Ni-Mo coatings reduce hydrogen evolution reaction overpotential(HER) significantly, therefore it has suitable catalytic properties for HER.
    A few researches on pulse reverse palting of Ni-Mo coatings have been published. in this work, we have evaluated effects of PRC on some properties of Ni-Mo coating such as chemical composition, morphology, catalytic properties for HER, crystaline structure and hardness property. The results of atomic absorption spectroscopy(AAS)... 

    Synthesis and Electrochemical Evaluation of Graphene-Ni/Cu/Zn Nanocomposite Coating Modified by Pt/Ru Nanoparticles

    , Ph.D. Dissertation Sharif University of Technology Yaghoubinezhad, Yadollah (Author) ; Afshar, Abdollah (Supervisor)
    In this research,Graphene Oxide nanoplatelets (GO) were synthesized by chemically modified Hummer's method.After the GO nanosheets electrochemically reduced to graphene, nanoparticles imposed to this thin film.This optimized nanostructure coating was utilized for investigating the Hydrogen Evolution Reaction (HER) over the copper substrate. In order to optimize the kinetic of electrodeposition and reduction, diverse electrochemical approaches such as cyclic voltammetry, chronoamperometic and potentiometric as well as pulse electrodeposition methods were employed. Electrochemical procedures were aligned by Design of Experiment (DOE) ... 

    Synthesis and Characterization of Structured Nanocatalysts and Their Applications in Kinetics Study of Oxidation-reduction Reactions

    , Ph.D. Dissertation Sharif University of Technology Akbarzadeh Ferdosiehnezhad, Elham (Author) ; Gholami, Mohammad Reza (Supervisor) ; Rahman Setayesh, Shahbanoo (Co-Advisor)
    In present study, various cocatalysts were used to improve catalytic properties of metal oxides and oxy-acids. Ag3VO4/Ag3PO4/Ag and Cu2O/MoS2/rGO photocatalysts were synthesized. The photocatalytic activities of the prepared nanocomposites were evaluated by the photodegradation of dye in the heterogenous systems as a series of advanced oxidation reactions. The results revealed that heterojunction between two semiconductors may prevent fast electron-hole pair recombination and then improve efficiency and rate of dye photodegradation. Mechanism and kinetics of dye degradation were studied in the presence of new photocatalysts by using of different scavengers. In the other works, Pt-NiO/G and... 

    Kinetics Investigation of Oxygen Evolution from Water Oxidation in the Presence of Bismuth Vanadate Nanocatalysts

    , M.Sc. Thesis Sharif University of Technology Moradpour, Amin (Author) ; Rahman Setayesh, Shahrbanoo (Supervisor)
    In this project, BiVO4 , Mn3O4 and BiVO4- Mn3O4 nanocatalysts were synthesized using the hydrothermal method. The properties of these nanocatalysts were determined by XRD, SEM, FT-IR, DRS, PL, ICP, EDX, BET and AA techniques. Analysys XRD patterns and SEM images of samples confirmed monoclinic structure for BiVO4 and tetragonal structure for Mn3O4. The DRS and PL spectra showed adctrease in the band gap and electron – hole pair recombination for BM 60:40 relative to BiVO4. Oxygen production was studied in the presence of different percentages of BiVO4 and Mn3O4 in BiVO4 - Mn3O4 nanocomposite and was observed that the 60:40 wt.% (Bismuth vanadate 60% and manganese oxide 40%) produced more... 

    Kinetics and electrocatalytic behavior of nanocrystalline CoNiFe alloy in hydrogen evolution reaction

    , Article International Journal of Hydrogen Energy ; Volume 32, Issue 12 , 2007 , Pages 1686-1693 ; 03603199 (ISSN) Jafarian, M ; Azizi, O ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
    Electrocatalytic activity of electrodeposited nanocrystalline CoNiFe alloy in hydrogen evolution reaction (HER) was studied in 1 M NaOH solution. The steady-state polarization measurement and electrochemical impedance spectroscopy were used to determine the Tafel slope, the exchange current density and the activation energy. The simulation of the data obtained from these two methods, using a nonlinear fitting procedure, allowed us to determine the surface coverage and the rate constants associated with the mentioned reaction. The ac-impedance spectra measured at various overpotentials in the HER region exhibited three semicircles in the complex plane plots. The high-frequency semicircle was... 

    CVD growth of the nanostructured Ni3S2 thin films as efficient electrocatalyst for hydrogen evolution reaction

    , Article Vacuum ; Volume 188 , June , 2021 ; 0042207X (ISSN) Kajbafvala, M ; Moradlou, O ; Moshfegh, A. Z ; Sharif University of Technology
    Elsevier Ltd  2021
    The development of low cost and earth abundant electrocatalyst with high performance and desirable stability for hydrogen evolution reaction (HER) is an important issue in energy applications. Nickel sulfide thin films (NiSx) are formed on conductive nickel foam substrates via chemical vapor deposition (CVD) at 300 °C under low pressure condition. A single phase of Ni3S2 was produced by controlling the ratio of precursors. X-ray diffraction (XRD), field emission scanning electron spectroscopy (FESEM), X-ray photoelectron spectroscopy (XPS) and electrochemical measurements were conducted to characterize and compare properties of the samples. According to XRD and XPS data analysis, the growth... 

    Modification of Electrode Substrates Using Nanocomposites Including Carbon Nanomaterials and Multimetallic Nanoparticles for Electrocatalysis of some Fuel Cells Reactions

    , Ph.D. Dissertation Sharif University of Technology Rezaee, Sharifeh (Author) ; Shahrokhian, Saeed (Supervisor)
    In this research, nanocomposite containing reduced graphene oxide nanosheets (RGO) and trimetallic three-dimensional (3D) Pt-Pd-Co porous nanostructures was fabricated by galvanic replacement technique. First, GO suspension was drop-casted on the electrode surface, then GO film reduction was carried out by cycling the potential in negative direction to form the RGO on GCE (RGO/GCE). Then, electrodeposition of the cobalt nanoparticles (CoNPs) as sacrificial seeds was performed onto the RGO/GCE by using cyclic voltammetry. Afterward, Pt-Pd-Co 3D porous nanostructures fabrication occurs through galvanic replacement method based on a spontaneous redox process between CoNPs and solution... 

    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... 

    Investigation of the Effect of Various Electrolyte Additives to Increase the Overpotential of the Hydrogen and Oxygen Evolution Reactions in Lead-Acid Batteries

    , M.Sc. Thesis Sharif University of Technology Mohammadvand, Ali (Author) ; Taherinia, Davood (Supervisor)
    Lead-acid batteries have been used for over 150 years as a reliable means of storing electrical energy. These batteries have a variety of applications due to their high safety, reliable performance, and relatively easy manufacturing process, including in car starters, car lighting and combustion, electric vehicles (especially electric bicycles), and the resulting electrical energy storage. From renewable sources or pulsed power supplies in hybrid electric vehicles. Despite increasing advances in the performance and design of these batteries, there are still problems in this area. One of the most important of these is the electrolysis of water as a side reaction, which leads to the production... 

    Intrinsically Ru-doped suboxide TiO2nanotubes for enhanced photoelectrocatalytic H2generation

    , Article Journal of Physical Chemistry C ; Volume 125, Issue 11 , 2021 , Pages 6116-6127 ; 19327447 (ISSN) Khorashadizade, E ; Mohajernia, S ; Hejazi, S ; Mehdipour, H ; Naseri, N ; Moradlou, O ; Moshfegh, A. Z ; Schmuki, P ; Sharif University of Technology
    American Chemical Society  2021
    In the present research, we investigate the synergistic effects of Ru-doping and Ar/H2 reduction treatment on the photoelectrochemical water splitting performance and hydrogen evolution rate of TiO2 nanotube array photoelectrodes. The Ti-Ru alloy with 0.2 at. % Ru was used to grow anodic self-organized Ru-doped TiO2 nanotube layers. An ideal synergy between Ar/H2 reduction treatment and Ru-doping results in the extended absorption toward the visible light region and improved photoelectrocatalytic activity. The black Ru-doped TiO2-x photoanode's water splitting rate improves remarkably (∼ninefold) compared to the black TiO2-x sample (∼twofold). Moreover, the black Ru-doped TiO2-x photoanode... 

    Facile synthesis of highly efficient bifunctional electrocatalyst by vanadium oxysulfide spheres on cobalt-cobalt sulfonitride nanosheets for oxygen and hydrogen evolution reaction

    , Article Electrochimica Acta ; Volume 391 , 2021 ; 00134686 (ISSN) Asen, P ; Esfandiar, A ; Sharif University of Technology
    Elsevier Ltd  2021
    Synthesis of efficient, low-cost, and stable bifunctional electrocatalysts with earth-abundant resources for electrochemical water electrolysis is a challenging subject for large-scale energy conversion processes. Herein, we report a high-performance electrocatalyst based on vanadium oxysulfide/cobalt-cobalt sulfonitride (VOS/Co-CoSN) for oxygen and hydrogen evolution reaction (OER and HER). The Co-CoSN film was synthesized on a copper sheet (CS) by a facile electrodeposition method. Then, VOS was electrochemically grown onto the Co-CoSN@CS electrode at various deposition times. At the optimal deposition time (300 s), the obtained VOS-300/Co-CoSN catalyst was studied for OER and HER in... 

    Investigaion Properties of Electrocatalytic Transition Metal Chalcogenids Nanocomposite in Hydrogen and Oxygen Evolution Reactions

    , M.Sc. Thesis Sharif University of Technology Moazzeni, Mohammad (Author) ; Taherinia, Davood (Supervisor)
    Electrochemical water splitting which consists of two half-reactions, namely; the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), is an important process in electrochemical energy storage and sustainable production of energy. Therefore, the development of cost-effective and efficient electrocatalysts for water splitting has attracted a lot of interest. In this work, a new nanocomposite was prepared from cobalt diselenide and cerium (IV) oxide derived from calcination of a cerium-based metal-organic framework (Ce-MOF), via hydrothermal and electrodeposition methods. The structure and morphology of synthesized materials were investigated by XRD, FE-SEM, EDX, and BET... 

    Investigation of Electrocatalytic Behavior of Some Transition Metal Oxides, Sulfides and Phosphides Nanostructures Toward Electrochemical Water Splitting

    , M.Sc. Thesis Sharif University of Technology Shamloofard, Maryam (Author) ; Shahrokhian, Saeed (Supervisor)
    Energy and the environment issues are among the most important concerns of the present age. Global demand for energy is growing rapidly and energy demand is projected to double in the coming years. However, today most of the energy consumption comes from fossil fuels, which have limited and unstable reserves and are among the sources of environmental pollution. Hence, the production and conversion of clean energy from renewable sources is considered as an intelligent solution to significantly reduce dependence on fossil fuels and protect the environment. Fuel cells, metal-air batteries, and water electrolysis are among the simplest, most efficient, and most reliable technologies among... 

    A kinetic study on the electrodeposition of nickel nanostructure and its electrocatalytic activity for hydrogen evolution reaction

    , Article Journal of Applied Electrochemistry ; Volume 40, Issue 11 , November , 2010 , Pages 1941-1947 ; 0021891X (ISSN) Torabi, M ; Dolati, A ; Sharif University of Technology
    The electrodeposition of nickel was studied using electrochemical techniques in different electrolytes and various agents. The voltammetry analysis clearly showed that the electrodeposition of nickel was a diffusion-controlled process associated with a typical nucleation process. The current transients represented instantaneous nucleation with a typical three-dimensional (3D) growth mechanism. Scharifker's equations were derived for instantaneous and progressive nucleation of the 3D growth of the spherical centers under diffusion-controlled condition. The number of nucleation sites increased with the increment in overpotential and Ni 2+ concentration. Atomic force microscopy was used to... 

    One-pot microwave synthesis of hierarchical C-doped CuO dandelions/g-C3N4 nanocomposite with enhanced photostability for photoelectrochemical water splitting

    , Article Applied Surface Science ; Volume 530 , 2020 Hosseini Hosseinabad, S. M ; Siavash Moakhar, R ; Soleimani, F ; Sadrnezhaad, S. K ; Masudy Panah, S ; Katal, R ; Seza, A ; Ghane, N ; Ramakrishna, S ; Sharif University of Technology
    Elsevier B.V  2020
    Cupric oxide (CuO) is a semiconductor of choice for photocathode in photoelectrochemical (PEC) applications due to its great sunlight absorption capability. However, photocorrosion is the main drawback of CuO. Herein, CuO/graphitic carbon nitride (g-C3N4) with a unique microstructure, enhanced PEC performance, and considerable photostability is synthesized under microwave irradiation. A facile, one-pot method is utilized to directly deposit the nanocomposite onto fluorine-doped tin oxide from a solution containing copper precursor and urea. Possible mechanism of CuO/g-C3N4 formation through this novel method is investigated. It is elucidated that controlled amounts of urea critically... 

    Shape-controlled synthesis of thorn-like 1D phosphorized Co supported by Ni foam electrocatalysts for overall water splitting

    , Article Journal of Materials Science: Materials in Electronics ; Volume 32, Issue 13 , 2021 , Pages 18363-18370 ; 09574522 (ISSN) Nourmohammadi, Khiarak, B ; Asaadi Zahraei, A ; Nazarzadeh, K ; Akbari Hasanjani, H. R ; Mohammadzadeh, H ; Sharif University of Technology
    Springer  2021
    A cost-effective, durable, and easy-to-produce improvement in bifunctional electrocatalysts for water splitting is crucial for future renewable energy systems. In this present study, shape-controlled one-dimensional (1D) phosphorized cobalt (CoP) on 3D porous nickel foam (NiF) was synthesized through successive treatment of commercial NiF with acetone and ethanol, followed by hydrothermal growth of Co and final process of phosphorization by thermochemical reactions. The evaluations of products proved reduced overpotential (270 mV at 10 mA. cm−2 for hydrogen evolution reaction (HER) process and a low overpotential of 320 mV to reach a high current density of 20 mA. cm−2), low Tafel slope...