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2. Defective TiO2 Nanotube Arrays for Efficient PhotoelectrochemicalDegradation of Organic PollutantsManel Machreki, Takwa Chouki, Georgi Tyuliev, Dušan Žigon, Bunsho Ohtani, Alexandre Loukanov, Plamen Stefanov, Saim Emin, 2023, izvirni znanstveni članek Opis: Oxygen vacancies (OVs) are one of the most critical factors that enhance the electrical and catalytic characteristics of metal oxide-based photo-electrodes. In this work, a simple procedure was applied to prepare reduced TiO 2 nanotube arrays (NTAs) (TiO 2−x) via a one-step reduction method using NaBH 4. A series of characterization techniques were used to study the structural, optical, and electronic properties of TiO 2−x NTAs. X-ray photoelectron spectroscopy confirmed the presence of defects in TiO 2−x NTAs. Photoacoustic measurements were used to estimate the electron-trap density in the NTAs. Photoelectrochemical studies show that the photocurrent density of TiO 2−x NTAs was nearly 3 times higher than that of pristine TiO 2. It was found that increasing OVs in TiO 2 affects the surface recombination centers, enhances electrical conductivity, and improves charge transport. For the first time, a TiO 2−x photoanode was used in the photo-electrochemical (PEC) degradation of a textile dye (basic blue 41, B41) and ibuprofen (IBF) pharmaceutical using in situ generated reactive chlorine species (RCS). Liquid chromatography coupled with mass spectrometry was used to study the mechanisms for the degradation of B41 and IBF. Phytotoxicity tests of B41 and IBF solutions were performed using Lepidium sativum L. to evaluate the potential acute toxicity before and after the PEC treatment. The present work provides efficient PEC degradation of the B41 dye and IBF in the presence of RCS without generating harmful products.
Ključne besede: TiO2 Nanotube Arrays, PhotoelectrochemicalDegradation of Organic Pollutants
Objavljeno v RUNG: 12.06.2023; Ogledov: 371; Prenosov: 3
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3. Oxygen vacancies engineering in metal oxide nanomaterials for efficient photo-electrocatalytic degradation of organic pollutants and chemical transformations : dissertationManel Machreki, 2022, doktorska disertacija Ključne besede: titanium dioxide nanotubes, hematite, oxygen vacancies, photoelectrochemical degradation of dye, ibuprofen, chemical transformation, glycerol, vanillyl alcohol, dissertations
Objavljeno v RUNG: 01.03.2023; Ogledov: 738; Prenosov: 25
Celotno besedilo (5,71 MB) |
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5. Iron phosphide thin films for electrocatalytic H2 generation and water remediation studies : abstractTakwa Chouki, Manel Machreki, Jelena Topic, Lorena Butinar, Plamen Stefanov, Erika Jez, Jack S Summers, Matjaz Valant, Aaron Fait, Saim Emin, 2022, objavljeni povzetek znanstvenega prispevka na konferenci Ključne besede: Iron phosphide thin films
H2 generation
water remediation
Objavljeno v RUNG: 10.02.2023; Ogledov: 532; Prenosov: 0
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6. Reduced TiO2 nanotube arrays for photoelectrochemical degradation of pharmaceuticalManel Machreki, Takwa Chouki, Georgi Tyuliev, Dušan Žigon, Bunsho Ohtani, Alexandre Loukanov, Plamen Stefanov, Saim Emin, 2022, objavljeni povzetek znanstvenega prispevka na konferenci Ključne besede: TiO2, nanotube arrays, photoelectrochemical degradation, pharmaceuticals
Objavljeno v RUNG: 10.02.2023; Ogledov: 489; Prenosov: 0
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7. Iron phosphide as an efficient electrocatalysts for hydrogen evolution : abstractTakwa Chouki, Manel Machreki, Saim Emin, 2020, objavljeni povzetek znanstvenega prispevka na konferenci Opis: We report the solvothermal synthesis of iron phosphide electrocatalysts using a low-cost phosphorus precursor. The synthetic protocol allows for the preparation of a Fe2P phase at 300°C and FeP phase at 350°C. To enhance the catalytic activities of obtained iron phosphide particles, heat-treatments were carried out at elevated temperatures. Annealing at 500°C induced structural changes in the samples: (i) Fe2P provided a pure Fe3P phase (Fe3P−500°C) and (ii) FeP transformed into a mixture of iron phosphide phases (Fe2P/FeP−500°C). The electrocatalytic activities of heat-treated Fe2P−450°C, Fe3P−500°C, and Fe2P/FeP−500°C catalysts were studied for hydrogen evolution reaction (HER) in 0.5 M sulfuric acid (H2SO4). The lowest recorded overpotential of 110 mV at 10 mA cm−2 vs. a reversible hydrogen electrode was achieved with Fe2P/FeP−500°C catalyst. The present approach allows preparation of immobilized iron phsphide catalyst onto carbon support which is essential for application purpose. The procedure developed by us is an elegant approach to tune the composition of iron phosphide catalyst and control the morphology of particles
Ključne besede: solvothermal synthesis
iron phosphide
electrocatalysis
HER
Objavljeno v RUNG: 06.02.2023; Ogledov: 562; Prenosov: 0
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8. Iron phosphides as efficient electrocatalyst for hydrogen evolution and energy conversion : abstractSaim Emin, Takwa Chouki, 2021, objavljeni povzetek znanstvenega prispevka na konferenci Opis: Transition metal phosphides have been demonstrated as outstanding multifunctional catalysts in a broad range of energy conversion technologies. We developed a solvothermal synthesis approach for iron phosphide electrocatalystsusing a low-cost phosphorus precursor.The synthetic protocol allows for the preparation of a Fe2P phase at 300°C and FeP phase at 350°C. The obtained compounds were coated on conductive substrates to prepare catalysts thin films. Here, we exploited different phases of iron phosphide as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs) with an I−/I3− based electrolyte [2]. The solar-to-current conversion efficiency of the solar cells assembled with the Fe2P material reached 3.96±0.06%,which is comparable to the device assembled with a platinum (Pt) CE. In addition to DSSC
applications, the iron phosphides were used as electrocatalyst for H2 evolution (Fig. 1). To enhance the catalytic activities of obtained iron phosphide particles, heat-treatments were carried out at elevated temperatures.Annealing at 500°C induced structural changes in the samples: (i) Fe2P provided a pure Fe3P phase (Fe3P−500°C) and (ii) FeP transformed into a mixture of iron phosphide phases (Fe2P/FeP−500°C). The electrocatalytic activities for H2 evolution of heat-treated catalysts were studied in 0.5 M sulfuric acid (H2SO4). The HER activities of the iron phosphide catalyst were found to be phase dependent. The lowest recorded overpotential of 110 mV at 10 mA cm−2 vs. a reversible hydrogen electrode was achieved with Fe2P/FeP−500°C catalyst. The developed procedure is an elegant approach to tune the composition of iron phosphide catalyst and control the morphology of particles.
Ključne besede: Iron phosphides
electrocatalyst
hydrogen evolution
energy conversion
Objavljeno v RUNG: 06.02.2023; Ogledov: 525; Prenosov: 0
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9. Electrocatalytic Hydrogen Evolution with Transition Metal Based Compounds : abstractSaim Emin, Takwa Chouki, Manel Machreki, 2021, objavljeni povzetek znanstvenega prispevka na konferenci Opis: Electrocatalytic water splitting is one of the cleanest and sustainable way to generate hydrogen. Transition metal based electrocatalysts like iron phosphides (Fe2P, FeP), molybdenum diselenides (MoSe2), and tungsten carbides (W2C, WC) have unique advantages including competitive cost compared to platinum, controllable active sites, and electronic structures that could significantly enhance the hydrogen evolution reaction (HER). Here, we present a combination of approaches for preparing catalyst materials. As an elegant technique, colloidal synthesis was used to synthesize Mo and W nanoparticles. Combined with selenization and carbidation approaches at elevated temperature, it allowed to synthesize MoSe2, W2C, and WC thin films. The syntheses of Fe2P and FeP catalyst were achieved in one-stage using triphenylphosphine precursor. The obtained catalysts were applied in electrocatalytic HER studies.
Ključne besede: iron phosphides
molybdenum diselenide
tungtsen carbides
electrocatalysis
hydrogen evolution
Objavljeno v RUNG: 06.02.2023; Ogledov: 501; Prenosov: 0
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10. Growth of MoSe2 thin films and use in electrochemical hydrogen evolution : abstractTakwa Chouki, Borjana Donkova, Burhan can Aktarla, Plamen Stefanov, Saim Emin, 2020, objavljeni povzetek znanstvenega prispevka na konferenci Opis: We present the chemical vapor deposition (CVD) approach to grow MoSe2 thin films using colloidal molybdenum nanoparticles (Mo NPs). The synthetic protocol of Mo NPs was achieved using a wet-chemical method. The obtained Mo NPs were spin-coated on graphite substrates and heat-treated in the presence of selenium vapors at several temperatures (≥750 °C). The electrocatalytic activities of heat-treated MoSe2 thin
films were studied for hydrogen evolution reaction (HER) in 0.5 M sulfuric acid (H2SO4). The lowest recorded
overpotential of 218 mV at 10 mA cm−2 vs. a reversible hydrogen electrode was achieved with MoSe2−800°C catalyst. In addition, electrochemical impedance spectroscopy (EIS) was performed to access the charge-transfer resistance of the MoSe2 films. The colloidal approach combined with CVD is a promising route to produce carbon supported MoSe2 electrocatalyst for HER.
Ključne besede: MoSe2 thin films
CVD
HER
Objavljeno v RUNG: 06.02.2023; Ogledov: 487; Prenosov: 0
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