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Enhanced photocatalytic activity of ZnO/g-C3N4 nanofibers constituting carbonaceous species under simulated sunlight for organic dye removal
, Article Ceramics International ; Volume 47, Issue 18 , 2021 , Pages 26185-26196 ; 02728842 (ISSN) ; Samadi, M ; Pourjavadi, A ; Ramakrishna, S ; Moshfegh, A. Z ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Semiconductor-based photocatalysis is an efficient approach for degradation of organic pollutants. In this context, ZnO/g-C3N4 composite nanofibers containing carbonaceous species with different concentrations of g-C3N4 nanosheets (x = 0.25, 0.5, 1, 2, 10 wt%) noted as ZnO/carbon/(x wt%) g-C3N4 are prepared by electrospinning technique. For preparation of the composite nanofibers, bulk g-C3N4 is exfoliated to nanosheets, and then it is mixed with polyvinyl alcohol and appropriate zinc acetate content followed by electrospinning process. Thermal annealing of the as spun zinc acetate/poly(vinyl alcohol)/g-C3N4 nanosheets sample under N2 atmosphere leads to the formation of carbonaceous species...
A comprehensive review on planar boron nitride nanomaterials: From 2D nanosheets towards 0D quantum dots
, Article Progress in Materials Science ; Volume 124 , 2022 ; 00796425 (ISSN) ; Alem, S. A. A ; Hasanzadeh Azar, M ; Shayeganfar, F ; Manning, M. I ; Hatamie, A ; Pakdel, A ; Simchi, A ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Moving from two-dimensional hexagonal boron nitride (2D h-BN) flatlands towards their quantum sized zero-dimensional (0D) islands, as the newest member of the h-BN family, has recently opened up novel research areas due to the emergence of unique optical and physicochemical properties, excellent thermal and chemical stability, and desirable biocompatibility. This review elaborates on the fundamental properties of 2D and 0D h-BN nanomaterials and covers the latest progress in the fabrication and applications of BN nanosheets (BNNSs) and quantum dots (BNQDs). Initially, the transformation of properties in h-BN nanomaterials is discussed when moving from the 2D realm towards the 0D quantum...
Synthesis and Optical Properties of Titanium Nitride Nanoparticles Prepared by Arc Discharge Method in Liquid Nitrogen
, M.Sc. Thesis Sharif University of Technology ; Irajizad, Azam (Supervisor) ; Ahmadian, Mohammad Mehdi (Supervisor)
Abstract
Production of nano-particles using arc-discharge method in a liquid nitrogen environment is a proficient way of forming nitride Particles whose formation by other methods is difficult and expensive. Amongstall, Titanium nitride (TiN) is of significant importance because of its high formidability and its optical and electrical metal properties due to plasmonic electrons. This research studies the production of titanium nitride Nano-particles using arc-discharge method and investigates optical properties and features, specially dielectric constant and optical extinction coefficient. Modeling interband Transitions is also discussed to revise Drude's electron theory. First, in experimental...
Synthesis of Tin and Ti2n Nanostructured Coatings on Ti alloys Using Magnetron Sputtering System And Comparison of Their Biocompatibility Properties
, M.Sc. Thesis Sharif University of Technology ; Nemati, Ali (Supervisor) ; Khamse, Sara (Supervisor)
Abstract
Considering the importance of biocompatibility of implantable prothesis’, metallic alloys have weaker corrosion resistance than ceramics. In order to extend usage of nanomaterials to improve the bio-properties of materials, Nano-structured ceramic coatings are being suggested to improve corrosion resistance and biocompatibility of prosthesis. Meanwhile, very good properties of TiN, such as corrosion resistance and mechanical properties as a thin film coating are undeniable. In this study, TiN and Ti2N thin film were deposited on Ti-based substrate, using PVD and Magnetron sputtering at different argon to nitrogen ratio. The crystal structure of the films was examined using Grazing XRD...
Investigation of Si3n4 Nano Particle Addition on the Hardening Behavior of Anodized Coated 1050 Aluminum Alloy
, M.Sc. Thesis Sharif University of Technology ; Afshar, Abdollah (Supervisor)
Abstract
In the present study, it has been tried out to increase the hardness and wear resistance of anodized aluminum coating byadding Si3N4 nanoparticles to the anodizing bath and making a composite coating. In order to investigate the influence of other effective parameters on the properties of anodized coating before the compositing process, hardness and thickness were optimized in the Sulphoric/oxalic bath using design of experimental method (central composite design). The properties of these coatings are dependent on various parameters among which time, temperature and pulse current parameters (current density limit, frequency and duty cycle) were considered in the present study. Analysis of...
Degradation of Model Textile Dyes in Wastewater using Visible-Light Active Photocatalysts
, M.Sc. Thesis Sharif University of Technology ; Soltanieh, Mohammad (Supervisor) ; Vossoughi, Manouchehr (Co-Supervisor) ; Padervand, Mohsen (Co-Supervisor)
Abstract
Textile dyes are a major category of organic pollutants and release of them in the environment causes serious problems. Among the most commonly used methods for colored wastewater, advanced oxidation processes, especially the photocatalytic process, are rapidly developing as a new and effective solution. However, there is still a need for high-level photocatalytic activity and improvement of this process to increase removal efficiency. In this study, we have tried to provide a higher performance for color removal using carbon nitride photocatalyst. Accordingly, two approaches have been proposed to improve the removal of rhodamine b, as one of the common dyes in the textile industries. The...
Kinetics of Adsorption of DBT Sulfur Containing Compound of Gasoline via Nanostructured Adsorbent
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhad, Khatiboleslam (Supervisor)
Abstract
Based on the new standards, less than 10 ppm sulfur is allowed for the automotive fuels. This has led researchers to try improving the present conventional methods as well as seeking alternative routes for refinement of the petroleum products so much to comply with the requirements. Since thiophenic fragments such as dibenzothiophene (DBT) are the most durable sulfur compounds in the current hydrodisulfurization method, many studies have been conducted over recent years on how to remove these compounds. In this thesis, the desulfurization of dibenzothiophene from gasoline via adsorption method was studied. In order to carry out the adsorption process, a nanocomposite of graphitic-carbon...
Modeling and Simulation of a High Power Photoconductive Semiconductor Switch (PCSS)
, M.Sc. Thesis Sharif University of Technology ; Faez, Rahim (Supervisor)
Abstract
There are a wide variety of light-triggered switches. Photoconductive semiconductor switches (PCSSs) have been investigated intensively for many applications owing to their unique advantages over other switches. The advantages of PCSSs make them a perfect choice for many important applications where high switching accuracy and high-power capability are required. Photoconductive switches are fabricated from a variety of semiconductors, including silicon carbide (SiC), gallium arsenide (GaAs) and gallium nitride (GaN). In Photoconductive semiconductor switches (PCSSs) the switching mechanism is initiated by optical illumination and laser source controls the flow of current. In the off or...
Synthesis of the Graphitic Carbon Nitride/Iron Oxide Nanocomposite
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhad, Khatiboleslam (Supervisor)
Abstract
The g-C3N4/Fe2O3 nanocomposite was produced by the combustion synthesis. The product was characterized by x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller study (BET), Ultraviolet-visible analysis (UV-vis) and photoluminescence measurement (PL). Effect of iron nitrate on stability and photocurrent density under simulated visible-light irradiation was determined. The highest photocurrent density obtained (4.25 μA/Cm2) was twelve times the pure g-C3N4. This improvement was due to a bandgap decrease, the specific surface area increase, reduction of the electron-hole recombination, and...
Copper Oxide/g-C3N4 Nanocomposites: Synthesis and Optical and Photocatalytic Properties Investigation
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhaad, Khatiboleslam (Supervisor)
Abstract
Herein, cupric oxide (CuO)/graphitic carbon nitride (g-C3N4) is synthesized under microwave irradiation for enhanced photoelectrochemical (PEC) performance and photostability. A facile, one-pot method was utilized to directly deposit the nanocomposite onto FTO from a solution containing copper precursor and urea. Possible mechanisms of CuO/g-C3N4 formation and PEC performance improvement were examined via XRD, FTIR, FESEM, XPS, UV-Vis, and PL. Controlled amounts of urea determined the morphological evolution of CuO and the formation of a protective carbon layer, while its excess quantity converted to g-C3N4 in the presence of CuO. Through heat treatment of the nanocomposite, carbon-doped...
Investigation of Wear Resistance and Microstructure of Ti-CP Coated by TIG Hardfacing Method Using Cored Wire Electrodes in Argon/Nitrogen Atmosphere
, M.Sc. Thesis Sharif University of Technology ; Kokabi, Amir Hossain (Supervisor)
Abstract
In present study, a CP-Ti surface was coated with cored wire electrodes filled with graphite powder by means of TIG cladding technique. The process was performed under controlled atmosphere with different composition of Argon and Nitrogen. The parameters of the process were changed in order to investigate the resulting effect on the coating microstructure and the wear properties. The microstructure and the composition in the weld and heat affected zone were carefully investigated by optical microscope, SEM, EDS and XRD. As the result, TiC dendrites were produced in-situ with different morphologies which are dependent on variation of the parameters. Moreover, TiN dendrites were in-situ...
Degradation of Organic Pollutants in Water by Advanced Oxidation Process Using MIL-based Nanostructured Catalyst
, M.Sc. Thesis Sharif University of Technology ; Kazemini, Mohammad (Supervisor) ; Mahmoodi, Nyaz Mohammad (Supervisor)
Abstract
Octahedral crystals of Fe-Metal-organic frameworks like Fe-MIL-101, which is the most stable and active metal-organic frameworks; in combination with graphitic carbon nitride nanosheets could significantly enhance the photocatalytic activity of g-C3N4 for inorganic dye degradation under the irradiation of visible light application. This appropriate cocatalyst modifies the performance of semiconductor via suppressing the recombination of photo-induced carriers and since the synthesized composite prepared by in-situ procedure possesses close contact between each other, the migration of electrons in the photocatalytic reaction will be continued, so the degradation process via the active species...
Synthesis and Characterization of Core-shell Nanoparticles Anchored Reduced Graphene Oxide (rGO) and Kinetic Investigation of Oxygen Evolution from Water Oxidation in the Presence of these Nanocatalysts
, M.Sc. Thesis Sharif University of Technology ; Rahman Setayesh, Shaherbanoo (Supervisor) ; Taherinia, Davood (Co-Supervisor)
Abstract
The reaction of oxygen evolution, in other words, the process of water oxidation in the presence of heterogeneous photocatalysts such as g-C3N4, Co/g-C3N4 /rGO, Ni/g-C3N4/rGO, CoNi/g-C3N4 / rGO, Co2Ni1/g-C3N4/rGO, and Co1Ni2 /g-C3N4 /rGO were studied. The characterization of these nanocatalysts was done by XRD, SEM, FT-IR, BET, DRS, CHN, and TGA techniques. Thermogravimetric analysis (TGA) was used to check the thermal stability of these nanocatalysts. The FT-IR spectroscopy was used to identify the functional groups in graphitic carbon nitride and to confirm g-C3N4 synthesis. According to BET results, the pore sizes were determined which were at the nano and macro scale. It was found that...
The Morphological Effects of Surface Modified Mos2 Nanosheets and Mos2 Qd/G-C3n4 Heterostructure Prepared by Chemical Methods in Hydrogen Evolution Reaction (Her)
, Ph.D. Dissertation Sharif University of Technology ; Moshfegh, Alireza (Supervisor) ; Naseri, Naeimeh (Co-Supervisor)
Abstract
The sustainable development in societies and the global energy challenge requires usage of clean energy systems that have attracted the attention of many researchers in recent decades. One of the major challenges in generating renewable resources is the problem of energy storage and imbalance between supply and demand cycles. Hydrogen as one of the clean energy carriers and due to having the highest energy density in terms of weight, is one of the important research topics. From this point of view, the preparation of electrocatalysts for hydrogen production, based on available materials, via simple and environmentally friendly production methods, was considered in this research....
Design and Construction of Fluorescent Confocal Microscopy Setup for Detection of Single Photon Emitters in 2d Materials
, M.Sc. Thesis Sharif University of Technology ; Esfandiar, Ali (Supervisor)
Abstract
The main goal of this research is to detect and characterize single-photon emitters in two-dimensional hexagonal boron nitride crystal with the help of fluorescence confocal microscope and Hanbury-Brown and Twiss interferometer. The origin of single-photon radiation in this crystal is not precisely known. It seems that the transition between energy levels, which occurs due to the presence of point defects in the crystal structure of this material, in the distance between the conduction and valence bands, is the source of single-photon radiation. This material does not require low temperature for single-photon radiation, which is an important advantage for it. In a confocal microscope, the...
Modeling of Vertical Tunneling Transistor based on Gr-hBN-MoSe2 Heterostructure
, M.Sc. Thesis Sharif University of Technology ; Faez, Rahim (Supervisor)
Abstract
In this thesis, the transmission characteristics of a vertical tunneling transistors based on graphene-hBN-MoSe2 heterostructure is studied. We first obtain the tight-binding parameters required for Hamiltonian matrix and bandstructure calculations using density functional theory results. Once we have the tight-binding parameters, Hamiltonian and coupling matrices are calculated both of size 326×326. We then proceed to calulate the density of stated for source and drain contacts using the aforementioned matrices and nonequilibrium Green’s function(NEGF) formalism. We can then calculate the quantum capacitances of source and drain and acquire source/drain potentials using a capacitive circuit...
Synthesis and Characterization of Boron Nitride Composites Based on Bio- and Synthetic Polymers and Investigation of Their Applications
, Ph.D. Dissertation Sharif University of Technology ; Pourjavadi, Ali (Supervisor)
Abstract
In recent years, the crude oil spills in the oceans and the excessive emission of electromagnetic waves in the living environment have threatened human health. Therefore, different methods have been considered to deal with each of these two threats. Recently, the use of polymeric boron nitride composites in the production of crude oil absorbents and electromagnetic wave shieldings has received attention due to its thermal conductivity, thermal and chemical stability. In the first step of this research, superhydrophobic composites of polyurethane sponges were prepared by boron nitride and electrically conductive nanomaterials that had photothermal and electrothermal properties. The results...
Synthesis and Characterization of g-C3N4 Containing Composite Scaffolds for Bifunctional Anti-Cancer/Tissue Engineering Application
, M.Sc. Thesis Sharif University of Technology ; Madaah Hosseini, Hamid Reza (Supervisor)
Abstract
Today, due to changes in lifestyle and environmental changes, the incidence of cancer is increasing worldwide. With the advancement of science and technology, humans have always sought ways to improve their quality of life and lifespan. The most common cancer related to bone tissue is osteosarcoma. One of the most effective treatment methods is photodynamic therapy. This method requires a photosensitizer with appropriate optical and biological properties. The ideal photosensitizer should be excited with light in the NIR range and produce ROS or active oxygen species. In this research, oxygen-doped graphitic carbon nitride modified by heterojunction with Mn3O4 was used as a photosensitizer....
Synthesis and Characterization of the Multifunctional Fe3O4@Mn3O4-LCysteine-g-C3N4 QDs System as a Contrast Agent for Dual-Model Magnetic Resonance and Fluorescence Imaging
, M.Sc. Thesis Sharif University of Technology ; Madaah Hosseini, Hamid Reza (Supervisor) ; Khachatourian, Adrine Malek (Supervisor)
Abstract
Cancer is one of the most important problems that affects public health. If this disease is diagnosed quickly in the patient's body, it can be prevented and treated by determining the stage of the disease and establishing a treatment protocol. Magnetic resonance imaging (MRI) and fluorescence imaging (FI) are among the imaging methods. In order to increase the contrast of images, researchers have turned to the synthesis of materials under contrast agents, which improve diagnostic sensitivity. Synthesis of nanoparticles as multi-mode contrast agents can enhance imaging methods. In this research, the synthesis and characterization of the multifunctional Fe3O4-Mn3O4-LCysteine@g-C3N4 QDs system...
Extreme light absorption in a necking-free monolayer of resonant-size nanoparticles for photoelectrochemical cells
, Article Journal of Optics (United Kingdom) ; Vol. 16, issue. 7 , 2014 ; ISSN: 20408978 ; Sharif University of Technology
Abstract
Semiconductor photoelectrodes for water oxidation that absorb visible light usually have poor electronic transport properties and small optical absorption coefficients near their absorption edge. Therefore, innovative designs that lead to significant optical absorption in relatively thin layers of these compounds are highly desirable. Here, using full-field electromagnetic optical simulations, we demonstrate that a monolayer of resonant-size BiVO4 spheres can provide enhancement up to a factor of two in solar light absorption relative to dense planar layers. In this monolayer, BiVO4 spheres do not need to be interconnected; therefore, such monolayers are flexible and their fabrication...