1. Oxygen vacancies engineering in metal oxide nanomaterials for efficient photo-electrocatalytic degradation of organic pollutants and chemical transformations : dissertationManel Machreki, 2022, doctoral dissertation Keywords: titanium dioxide nanotubes, hematite, oxygen vacancies, photoelectrochemical degradation of dye, ibuprofen, chemical transformation, glycerol, vanillyl alcohol, dissertations Published in RUNG: 01.03.2023; Views: 331; Downloads: 13
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3. 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, published scientific conference contribution abstract Keywords: Iron phosphide thin films
H2 generation
water remediation Published in RUNG: 10.02.2023; Views: 292; Downloads: 0 This document has many files! More... |
4. 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, published scientific conference contribution abstract Keywords: TiO2, nanotube arrays, photoelectrochemical degradation, pharmaceuticals Published in RUNG: 10.02.2023; Views: 255; Downloads: 0 This document has many files! More... |
5. Iron phosphide as an efficient electrocatalysts for hydrogen evolution : abstractTakwa Chouki, Manel Machreki, Saim Emin, 2020, published scientific conference contribution abstract Abstract: 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 Keywords: solvothermal synthesis
iron phosphide
electrocatalysis
HER Published in RUNG: 06.02.2023; Views: 282; Downloads: 0 This document has many files! More... |
6. Electrocatalytic Hydrogen Evolution with Transition Metal Based Compounds : abstractSaim Emin, Takwa Chouki, Manel Machreki, 2021, published scientific conference contribution abstract Abstract: 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. Keywords: iron phosphides
molybdenum diselenide
tungtsen carbides
electrocatalysis
hydrogen evolution Published in RUNG: 06.02.2023; Views: 267; Downloads: 0 This document has many files! More... |
7. Highly active iron phosphide catalysts for selective electrochemical nitrate reduction to ammoniaTakwa Chouki, Manel Machreki, Iwona Rutkowska, Beata Rytelewska, Pawel J. Kulesza, Georgi Tyuliev, Moussab Harb, Luis Miguel Azofra, Saim Emin, 2023, original scientific article Abstract: The electrochemical reduction reaction of the nitrate ion (NO3−), a widespread water pollutant, to valuable ammonia (NH3) is a promising approach for environmental remediation and green energy conservation. The development of high-performance electrocatalysts to selectively reduce NO3− wastes into value-added NH3 will open up a different route of NO3− treatment, and impose both environmental and economic impacts on sustainable NH3 synthesis. Transition metal phosphides represent one of the most promising earth-abundant catalysts with impressive electrocatalytic activities. Herein, we report for the first time the electrocatalytic reduction of NO3− using different phases of iron phosphide. Particularly, FeP and Fe2P phases were successfully demonstrated as efficient catalysts for NH3 generation. Detection of the in-situ formed product was achieved using electrooxidation of NH3 to nitrogen (N2) on a Pt electrode. The Fe2P catalyst exhibits the highest Faradaic efficiency (96 %) for NH3 generation with a yield (0.25 mmol h−1 cm-−2 or 2.10 mg h−1 cm−2) at − 0.55 V vs. reversible hydrogen electrode (RHE). The recycling tests confirmed that Fe2P and FeP catalysts exhibit excellent stability during the NO3− reduction at − 0.37 V vs. RHE. To get relevant information about the reaction mechanisms and the fundamental origins behind the better performance of Fe2P, density functional theory (DFT) calculations were performed. These results indicate that the Fe2P phase exhibits excellent performance to be deployed as an efficient noble metal-free catalyst for NH3 generation. Keywords: Iron phosphide, Electrocatalysts, Nitrates reduction Ammonia, DFT calculations Published in RUNG: 02.02.2023; Views: 342; Downloads: 0 This document has many files! More... |
8. Iron phosphide precatalyst for electrocatalytic degradation of rhodamine B dye and removal of Escherichia coli from simulated wastewaterTakwa Chouki, Manel Machreki, Jelena Topić, Lorena Butinar, Plamen Stefanov, Erika Jež, Jack S. Summers, Matjaž Valant, Aaron Fait, Saim Emin, 2022, original scientific article Keywords: železov fosfat, elektrokataliza, rodamin Published in RUNG: 02.08.2022; Views: 610; Downloads: 92
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9. Photoelectrocatalytic water splitting and dye degradation with fluorine doped tin oxides filmsManel Machreki, Takwa Chouki, Saim Emin, 2019, published scientific conference contribution abstract Abstract: We report the photoelectrochemical (PEC) water splitting with flourine doped tin oxide (FTO) films. This is the first study where efficient water splitting is achieved with FTO films under light illumination. Potentiostatic test at 1.7 V vs reversible hydrogen electrode (RHE) show that FTO material is very stable for water oxidation without occurence of a noticable current drop over a span of 6 hours. Mass spectrometry analysis of evolved gasses confermed the formation of oxygen and hydrogen in the two half cells (separated by a membrane). Moreover, it was demonstrated that the water splitting reaction involve formation of hydroxyl radicals (•OH) which are known oxidants for organics. We applied these FTO films for degradation of a model pollutant rhodamine B dye (1×10−5 mol/l). PEC assisted degradation of rhodamine B took about 30 min to achieve complete degradation of 60 ml model dye solution. Keywords: FTO, thin films, dye degradation Published in RUNG: 13.05.2021; Views: 1278; Downloads: 0 This document has many files! More... |
10. Solvothermal synthesis of iron phosphides and their application for efficient electrocatalytic hydrogen evolutionTakwa Chouki, Manel Machreki, Saim Emin, 2020, published scientific conference contribution abstract Abstract: We report the solvothermal synthesis of iron phosphide electrocatalysts using a low-cost phosphorus precursor [1]. 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 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 present approach allows the 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. Keywords: solvothermal synthesis, iron phosphide, electrocatalyst, hydrogen evolution, overpotential Published in RUNG: 13.05.2021; Views: 1371; Downloads: 0 This document has many files! More... |