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Synthesis and Investigation on Physical and Photoelectrochemical Properties of Visible Active TiO2/Graphene Based Nanocomposite Thin Films for Hydrogen Production
, Ph.D. Dissertation Sharif University of Technology ; Moshfegh, Alireza (Supervisor)
Abstract
World population growth, depletion of fossil fuels resources depletion and increased air pollution resulting from their consumption, human society has had to replace fossil fuels with renewable sources. In this context, the production of hydrogen using solar energy is feasible candidate to replace fossil fuels, which can be produced by water splitting in a photoelectrochemical (PEC) cell using an appropriate photocatalyst. This clean production method has been attended by many researchers in recent years. The most common photocatalyst for the conversion of sunlight to hydrogen by splitting water is Titanium dioxide (TiO2). But high energy gap and fast electron-hole recombination rate in TiO2...
Charge Transfer Complexes of Substituted Bis (thiophen-2-Ylmethylene)Benzene-1,4-Diamine Schiff Bases with Iodine and TCNE
, M.Sc. Thesis Sharif University of Technology ; Mohammadi Boghaei, Davar (Supervisor)
Abstract
The charge transfer interaction of two Schiff-bases 2,5-dichloro -bis(thiophen-2-ylmethylene)benzene-1,4-diamine and 2,5-dimethyl-bis(thiophen-2- ylmethylene) benzene-1,4-diamine as donors with I2 and TCNE ethylene as acceptors have been studied spectrophotometrically.
The formation constants and extinction coefficients of charge transfer complexes have been determined by graphical as well as iterative methods. From measurements at different temperatures the thermodynamic functions of the charge transfer complex formation have been studied. The temperature dependence of the K can be used for the determination of the thermodynamic reaction quantities (ΔG, ΔS, ΔH) for linear regression...
The formation constants and extinction coefficients of charge transfer complexes have been determined by graphical as well as iterative methods. From measurements at different temperatures the thermodynamic functions of the charge transfer complex formation have been studied. The temperature dependence of the K can be used for the determination of the thermodynamic reaction quantities (ΔG, ΔS, ΔH) for linear regression...
Direct conversion of inorganic complexes to platinum/thin oxide nanoparticles decorated on MOF-derived chromium oxide/nanoporous carbon composite as an efficient electrocatalyst for ethanol oxidation reaction
, Article Journal of Colloid and Interface Science ; Volume 555 , 2019 , Pages 655-666 ; 00219797 (ISSN) ; Rezaee, S ; Shahrokhian, S ; Amini, M. M ; Sharif University of Technology
Academic Press Inc
2019
Abstract
In this work, we present the design and fabrication of a novel nanocomposite based on noble metal and metal oxide nanoparticles dispersed on highly porous carbon obtained via the pyrolysis of an inorganic complex and metal-organic frameworks. This nanocomposite is prepared by a two-step procedure: first, the composite support of nanoporous carbon (NPC) is obtained by the direct carbonization of the Cr-benzene dicarboxylic ligand (BDC) MOF in an Argon atmosphere at 500 °C (Cr2O3-NPC). A mixture containing Cr2O3-NPC and [PtCl(SnCl3)(SMe2)2] is then prepared, and underflow of Argon is heated to 380 °C. Finally, Pt-SnO2 nanoparticles are loaded on the Cr2O3-NPC support, and the obtained...
First-principles study of molecule adsorption on Ni-decorated monolayer MoS2
, Article Journal of Computational Electronics ; Volume 18, Issue 3 , 2019 , Pages 826-835 ; 15698025 (ISSN) ; Berahman, M ; Asgari, R ; Sharif University of Technology
Springer New York LLC
2019
Abstract
The interactions between four different gas molecules (methanol, o-xylene, p-xylene and m-xylene) and Ni-decorated monolayer MoS2 were investigated by means of density functional computations to exploit its potential application as a gas sensor. The electronic properties of the Ni-decorated monolayer MoS2 and gas molecule (adsorbent–adsorbate properties) strongly depend on the Ni-decorated monolayer MoS2 structure and the molecular configuration of the adsorbate. The adsorption properties of volatile organic compound (VOC) molecules on Ni-decorated MoS2 has been studied taking into account the parameters such as adsorption energy, energy bandgap, density of states, and Mulliken charge...
Mechanism of photocatalytic reduction of CO2 by Ag3PO4(111)/g-C3N4 nanocomposite: a first-principles study
, Article Journal of Physical Chemistry C ; Volume 123, Issue 36 , 2019 , Pages 22191-22201 ; 19327447 (ISSN) ; Moshfegh, A. Z ; De Leeuw, N. H ; Sharif University of Technology
American Chemical Society
2019
Abstract
Density functional theory (DFT) calculations have been performed to investigate the electronic structure and photocatalytic activity of a hybrid Ag3PO4(111)/g-C3N4 structure. Due to Ag(d) and O(p) states forming the upper part of the valence band and C(p), N(p), and Ag(s) the lower part of the conduction band, the band gap of the hybrid material is reduced from 2.75 eV for Ag3PO4(111) and 3.13 eV for monolayer of g-C3N4 to about 2.52 eV, enhancing the photocatalytic activity of the Ag3PO4(111) surface and g-C3N4 sheet in the visible region. We have also investigated possible reaction pathways for photocatalytic CO2 reduction on the Ag3PO4(111)/g-C3N4 nanocomposite to determine the most...
How does cobalt phosphate modify the structure of TiO2 nanotube array photoanodes for solar water splitting?
, Article Catalysis Today ; Volume 335 , 2019 , Pages 306-311 ; 09205861 (ISSN) ; Naseri, N ; Calloni, A ; Bussetti, G ; Sharif University of Technology
Elsevier B.V
2019
Abstract
TiO2 nanotube arrays (TNA) have been modified by cobalt phosphate (CoPi) through potentiostatic electrodeposition method. Different samples have been prepared by changing the loaded CoPi through the deposition time from 10 to 960 min. Formed catalytic materials have been characterized by different methods. Although charge transfer resistance of the CoPi/TNA photoanodes have been decreased from 5.5 to 4.0 kΩ by increasing the deposition time from 5 to 60 min, the maximum photoresponse was obtained for 10 min CoPi deposition leading to 24% more photocurrent compare to bare TNA which proposed optimum value for cobalt phosphate decoration. Based on field emission scanning electron microscopy...
Synthesis and application of mesoporous carbon nanospheres containing walnut extract for fabrication of active protective epoxy coatings
, Article Progress in Organic Coatings ; Volume 133 , 2019 , Pages 206-219 ; 03009440 (ISSN) ; Behroozi Kohlan, T ; Momeni, S ; Ramazani S. A., A ; Mahdavian, M ; Sharif University of Technology
Elsevier B.V
2019
Abstract
In this article, the synthesis procedure of mesoporous carbon nanospheres (MCNSs) using silica hard-templates, doping of the nanospheres with walnut extract, and their impact on active protective properties of an epoxy coating are presented. Field emission scanning electron microscope (FE-SEM) results showed that the synthesis of these nanocontainers was successfully done in spherical form. Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR) results showed that walnut extract as a green inhibitor was doped into the pores of nanocapsules. Corrosion resistance of the mild steel samples in the 3.5 wt.% NaCl solution in the presence and absence of walnut extract...
A systematic investigation on the bactericidal transient species generated by photo-sensitization of natural organic matter (NOM) during solar and photo-Fenton disinfection of surface waters
, Article Applied Catalysis B: Environmental ; Volume 244 , 2019 , Pages 983-995 ; 09263373 (ISSN) ; Giannakis, S ; Gholami, M. R ; Feng, L ; Pulgarin, C ; Sharif University of Technology
Elsevier B.V
2019
Abstract
In this work, the role of dissolved oxygen in the solar and the photo-Fenton-mediated E. coli inactivation process was put under scrutiny. The effect of transient species that were produced in the presence of various natural organic matter isolates (NOM), namely Suwannee River (SR) NOM, Nordic Reservoir (NR) NOM, SR Humic acid (SRHA), and SR Fulvic acid (SRFA) was studied in detail. The role of 1 O2 in this reaction was systematically evaluated by modifying the O2 concentration (N2/O2 purging) and the matrix composition (10, 50, and 100% deuterium oxide (D2O) v/v). In the presence of NOM, 1 O2 was generated and the enhancement of E. coli inactivation rate due to charge transfer from triplet...
Mechanical and chemical pressure effects on the AeFe 2 As 2 (Ae = Ba, Sr, Ca) compounds: Density functional theory
, Article Computational Materials Science ; Volume 160 , 2019 , Pages 233-244 ; 09270256 (ISSN) ; Hadipour, H ; Akhavan, M ; Sharif University of Technology
Elsevier B.V
2019
Abstract
We have studied the pressure-induced structural, magnetic and electronic properties of AeFe 2 As 2 (Ae = Ba, Sr, Ca) compounds in the framework of density functional theory within the GGA-PBE method. The effects of chemical pressure generated by Sr and Ca substitutions in BaFe 2 As 2 have been investigated. We have found a magnetic transition at the same primitive unit cell volume, around 81 Å 3 for the (Ba⧹Ca)Fe 2 As 2 compounds, which predicts a magnetic transition pressure of 12 GPa for SrFe 2 As 2 . The structural parameters of FeAs 4 tetrahedra are obtained after ionic relaxation and compared with the existing experimental results. The change of these internal parameters is ascribed to...
Synthesis, first-principle simulation, and application of three-dimensional ceria nanoparticles/graphene nanocomposite for non-enzymatic hydrogen peroxide detection
, Article Journal of the Electrochemical Society ; Volume 166, Issue 5 , 2019 , Pages H3167-H3174 ; 00134651 (ISSN) ; Hatamie, A ; Berahman, M ; Simchi, M ; Angizi, S ; Rahmati, R ; Kennedy, J ; Simchi, A ; Sharif University of Technology
Electrochemical Society Inc
2019
Abstract
Owing to the exceptional properties of graphene and the crucial role of substrate on the performance of electrochemical biosensors, several graphene-based hybrid structures have recently emerged, yielding improved selectivity and sensitivity. To date, most of the reported biosensors utilize solution-driven graphene flakes with drawbacks of low conductivity (due to high inter-junction contact resistant) and structural fragility. Herein, we present a conductive three-dimensional CeO2 semiconductor nanoparticles/graphene nanocomposite, as a platform for sensitive detection of hydrogen peroxide, an important molecule in fundamental biological processes. The 3D conductive graphene architecture is...
Structural, microstructural and electrochemical studies of TiO2-Ag double layer coated NCM cathode for lithium-ion batteries
, Article Materials Research Express ; Volume 6, Issue 8 , 2019 ; 20531591 (ISSN) ; Ghorbanzadeh, M ; Sharif University of Technology
Institute of Physics Publishing
2019
Abstract
Lithium ion batteries as one of the most important energy storage equipments, have several challenges including capacity drop as number of cycles increases. Cathode particle coating is an effective approach in improvement of electrochemical performance of the batteries. In this study, TiO2-Ag coating was used to improve NCM cathode performance. The microstructure and crystal structure properties of coated NCMs were evaluated by the FE-SEM and XRD. Electrochemical behavior of the batteries was investigated by cycling performance analysis and EIS. TiO2 coating was deposited as a uniform layer and Ag coating was precipitated as dispersed nanoparticles. The results shows that using of TiO2-Ag...
Synthesis, first-principle simulation, and application of three-dimensional ceria nanoparticles/graphene nanocomposite for non-enzymatic hydrogen peroxide detection
, Article Journal of the Electrochemical Society ; Volume 166, Issue 5 , 2019 , Pages H3167-H3174 ; 00134651 (ISSN) ; Hatamie, A ; Berahman, M ; Simchi, M ; Angizi, S ; Rahmati, R ; Kennedy, J ; Simchi, A ; Sharif University of Technology
Electrochemical Society Inc
2019
Abstract
Owing to the exceptional properties of graphene and the crucial role of substrate on the performance of electrochemical biosensors, several graphene-based hybrid structures have recently emerged, yielding improved selectivity and sensitivity. To date, most of the reported biosensors utilize solution-driven graphene flakes with drawbacks of low conductivity (due to high inter-junction contact resistant) and structural fragility. Herein, we present a conductive three-dimensional CeO2 semiconductor nanoparticles/graphene nanocomposite, as a platform for sensitive detection of hydrogen peroxide, an important molecule in fundamental biological processes. The 3D conductive graphene architecture is...
Monolithic Solar Cells with Dye or Perovskite Light Absorbent
, Ph.D. Dissertation Sharif University of Technology ; Taghavinia, Nima (Supervisor)
Abstract
According to Iran's proper location to take advantage of solar energy and the ability of nanostructured solar cells fabrication in the country, in this study, the manufacturing problems and complexities of nanostructured solar cells such as dye solar cells and perovskite-based solar cells are investigated. The chromium metal as an alternative to the transparent conductive substrates in order to reduce the manufacturing cost of dye solar cells (DSCs) and reducing series resistance is introduced in this study. In case of utilizing chromium as a substrate for photoanode, the thickness of CrxOy layer is controlled by depositing TiO2 compact layer and the efficiency of DSC is increased from 2.6%...
Effective carbon composite electrode for low-cost perovskite solar cell with inorganic CuIn0.75Ga0.25S2 hole transport material
, Article Solar RRL ; Volume 4, Issue 5 , 2020 ; Forouzandeh, M ; Khosroshahi, R ; Meraji, K ; Badrabadi, M. N ; Dehghani, M ; Li, X ; Zhan, Y ; Liao, Y ; Ning, Z ; Taghavinia, N ; Sharif University of Technology
Wiley-VCH Verlag
2020
Abstract
Perovskite solar cells are well known for being low cost, solution-based, and efficient solar cells; however, the high price of the conventional hole-collector electrode (Spiro-OMeTAD/Gold) and the high price and complexity of depositing gold on large scales are major barriers against commercializing them. Herein, an effective carbon composite electrode is introduced for a low-cost perovskite solar cell with CuIn0.75Ga0.25S2 hole transport material to solve this problem. The carbon electrode is deposited by the doctor blade method using a paste composed of flakes of graphite, carbon black, and a kind of hydrophobic polymer (polystyrene or poly-methyl methacrylate). It is investigated how the...
Surface treatment of perovskite layer with guanidinium iodide leads to enhanced moisture stability and improved efficiency of perovskite solar cells
, Article Advanced Materials Interfaces ; Volume 7, Issue 14 , 2020 ; Prochowicz, D ; Tavakoli, M. M ; Yadav, P ; Hong, C. K ; Sharif University of Technology
Wiley-VCH Verlag
2020
Abstract
Interfacial engineering between the perovskite and hole transport layers has emerged as an effective way to improve perovskite solar cell (PSC) performance. A variety of organic halide salts are developed to passivate the traps and enhance the charge carrier transport. Here, the use of guanidinium iodide (GuaI) for interfacial modification of mixed-cation (Cs)x(FA)1−xPbI3 perovskite films, which results in the formation of a low-dimensional δ-FAPbI3-like phase on the 3D perovskite surface, is reported. The presence of this thin layer facilitates charge transfer at interfaces and reduces charge carrier recombination pathways as evidenced by enhanced carrier lifetimes and favorable interfacial...
Effect of indium ratio in CuInxGa1-xS2/carbon hole collecting electrode for perovskite solar cells
, Article Journal of Power Sources ; Volume 475 , 2020 ; Behrouznejad, F ; Ghavaminia, E ; Khosroshahi, R ; Li, X ; Zhan, Y ; Liao, Y ; Ning, Z ; Taghavinia, N ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Perovskite solar cells (PSCs) have excellent photovoltaic properties. There are, however, challenges of materials cost and device stability to be solved before commercializing them. Utilizing low-cost inorganic hole transport materials (HTM) as a replacement for spiro-OMeTAD, and replacing the Au electrode with printable carbon could be important steps in this regard. For this purpose, CuInxGa1-xS2 (x = 1, 0.75, 0.5, 0.25, 0) nanoparticle layers are deposited as inorganic HTMs with carbon composite electrode as the back electrode. Photovoltaic properties of PSCs with CuInxGa1-xS2/Carbon hole collecting electrodes are studied by changing the In ratio in the HTM layer. Results from impedance...
Sustainable starfish like cobalt electrocatalyst grown on optimized CNT-graphene hybrid host for efficient water oxidation
, Article Applied Surface Science ; Volume 524 , 15 September , 2020 ; Ghasemi, S ; Pourreza, M ; Moshfegh, A. Z ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Solar energy generation is one of the most efficient approach to solve emerging environment and energy challenges. In this context, solar assisted dissociation of water into oxygen and hydrogen utilizing scalable and high performance electrocatalysts plays key role since the produced hydrogen is a clean energy carrier. Here, cobalt based nanoflakes with metallic core and oxidized surface were grown on the designed carbonaceous layer for anodic oxygen evolution reaction (OER) using an electrochemical approach. Carbonaceous layers containing proper amount of carbon nanotubes (CNT) and reduced graphene oxide (rGO) species were used to optimize the system. Although higher weight percent of rGO...
Not completely innocent: how argon binding perturbs cationic copper clusters
, Article Journal of Physical Chemistry A ; Volume 124, Issue 43 , 2020 , Pages 9004-9010 ; Lushchikova, O. V ; Bakker, J. M ; Visscher, L ; Sharif University of Technology
American Chemical Society
2020
Abstract
Argon is often considered as an innocent probe that can be attached and detached to study the structure of a particular species without perturbing the species too much. We have investigated whether this assumption also holds for small copper cationic clusters and demonstrated that small but significant charge transfer from argon to metal changes the remaining binding positions, leading in general, to weaker binding of other argon atoms. The exception is binding to just one copper ion, where the binding of the first argon facilitates the binding of the second. © 2020 American Chemical Society
Influence of H-bonds on acidity of deoxy-hexose sugars
, Article Journal of Physical Organic Chemistry ; Volume 33, Issue 10 , June , 2020 ; Fattahi, A ; Sharif University of Technology
John Wiley and Sons Ltd
2020
Abstract
The unusual monosaccharaides such as deoxy-hexose sugars, including methyl-pentose and aldo-pentose, are promising and important sugars in life science. However, little research on H-bond interactions in these systems has been reported. The aldo-pentose has a proton instead of the CH2OH group on C5; conversely, methyl-pentose has a CH3 group on C5. The aim of the present study is to investigate the role and nature of intramolecular H-bonds on acidity of CH3-pentose sugars (L-fucose and L-rhamnose) and aldo-pentose sugars (D-xylose, L-lyxose, D-ribose, and L-arabinose) using B3LYP/6-311++G (d, p) level. The calculated acidity values (ΔHacid) of these Dexoy-hexose were found to be from 343 to...
AC characterization of three-dimensional reduced graphene oxide/molybdenum disulfide nanorose hybrids for ethanol vapor detection
, Article Applied Surface Science ; Volume 520 , August , 2020 ; Iraji zad, A ; Sharif University of Technology
Elsevier B. V
2020
Abstract
A novel AC impedance study on three-dimensional hybrid structures of graphene sheets/MoS2 nanorose (GMS) toward ethanol vapor detection is presented in this work. These defective 3D hybrid porous structures are sensitive to the presence of different gases as a result of charge transfer with gas species, as well as a change in the effective capacitance of the system. The sensing behavior of the samples is investigated throughout time-dependent impedance measurement and electrochemical impedance spectroscopy (EIS). The sensor response is estimated at about 20% to 10 ppm ethanol vapor, with the response and recovery times about 3.2 s and 0.8 s, respectively. Sensing mechanism proposed to...