Repozitorij Univerze v Novi Gorici

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Reduced TiO2 nanotube arrays for photoelectrochemical degradation of pharmaceutical
Manel 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: 259; Prenosov: 0
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Synthesis and application of transition metal phosphide nanomaterials as electrocatalysts for water splitting and chemical transformations : dissertation
Takwa Chouki, 2022, doktorska disertacija

Opis: In this thesis, we will focus on the solvothermal synthesis of iron phosphides (FeP, Fe2P) using triphenylphosphine (TPP) as an inexpensive and stable phosphorus source. The obtained iron phosphides were applied as electrocatalysts in hydrogen evolution reaction (HER), oxygen evolution reaction (OER), Rhodamine B (RhB) degradation, Escherichia coli (E. coli) inactivation, nitrates reduction reaction (NO3RR) to ammonia (NH3), and as counter electrodes in dye-sensitized solar cells (DSSCs). Detailed characterizations of catalysts were carried out to investigate the correlations between the material structure and catalytic activity. The first part of the thesis gives an introduction to the topic which cover overview of literature about the use of transition metal phosphide as efficient electrocatalysts in water splitting studies, NO3RR to NH3 and DSSCs. The second part is a description of the experimental methods. The third part discusses the solvothermal synthesis of FeP and Fe2P catalysts using TPP precursor. The phase conversion of iron phosphides at elevated temperatures under reductive atmosphere was reported. Structural characterizations of the obtained materials were achieved using multiple techniques. The electrocatalytic activities of heat-treated iron phosphide films for HER were studied in acidic environment. The fourth part discusses the use of Fe2P nanoparticles (NPs) for OER. The fifth part outlines the use of Fe2P precatalyst in water treatment studies. Using a thin film of Fe2P precatalyst, RhB degradation and E. coli inactivation in the presence of in-situ generated reactive chlorine species were reported. Characterization of Fe2P electrocatalysts before and after the test was carried out using different techniques. The sixth part shows for the first time the use of FeP and Fe2P as a noble metal-free electrocatalysts for NO3RR to NH3. In this chapter we will emphasize the nitrate reaction pathways, which are highly complex and poorly understood. The seventh part demonstrates the use of FeP and Fe2P catalysts as robust and efficient counter electrodes in DSSCs.
Ključne besede: solvothermal synthesis, iron phosphides, electrocatalysis, HER, OER, RhB degradation, E. coli inactivation, NO3RR to NH3, DSSCs, dissertations
Objavljeno v RUNG: 29.08.2022; Ogledov: 742; Prenosov: 72
.pdf Celotno besedilo (6,35 MB)
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Chemical (in)stability of interfaces between different metals and Bi[sub]2Se[sub]3 topological insulator
Katja Ferfolja, Mattia Fanetti, Sandra Gardonio, Matjaž Valant, 2018, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: In recent years a classification of materials based on their topological order gained popularity due to the discovery of materials with special topological character – topological insulators (TI). TI have different band structure than regular insulators or conductors. They are characterized by a band gap in the bulk of the material, but at the surface they possess conductive topological surface states (TSS) that cross the Fermi level. TSS are a consequence of the non-trivial bulk band structure and have properties that differ from ordinary surface states. They are robust toward contamination and deformation of the surface. Additionally, they are also spin polarized, which means that an electron spin is locked to a crystal momentum and, therefore, backscattering during transport is suppressed [1]. Due to their specific properties the TI could be used in fields of spintronics, quantum computing and catalysis [2]. The investigation of the interfaces between metals and the TI has not been given much attention even though its characterization is interesting from fundamental physics and applicative point of view. (In)stability of the contacts with metal electrodes, in a form of a chemical reaction or diffusion, has to be taken into account since it can affect the transport properties of the material or increase the contact resistance. Our research is dedicated to the study of the metal/TI interfaces, in particular to Bi2Se3 with deposited metals that are relevant for electrical contacts (Au, Ag, Pt, Cr, Ti). The thermal and chemical stability of the interfaces are of fundamental importance for understanding the contact behavior, therefore, we focused our work to the characterization of these properties. The metal/TI interfaces are investigated mainly with an electron microscopy (SEM, TEM, STM), EDX microanalysis and XRD. Our previous studies showed that the interface between Bi2Se3, and Ag deposited either chemically or from a vapor phase, results in the formation of new phases already at room temperature [3]. On the contrary, Au deposited on the Bi2Se3 surface shows very limited reactivity and is stable at RT, but diffusion and coalescence of the metal are observed starting from 100 °C [4]. In this contribution, we will present further characterization on the evolution of the Ag/Bi2Se3 and Au/Bi2Se3 interfaces, show preliminary results about recently investigated systems (Pt/Bi2Se3, Ti/Bi2Se3) and compare the thermal and chemical stability of the systems under investigation.
Ključne besede: thermal lens spectrometry, photothermal beam deflection spectroscopy, dye remediation, photothermal technique, photocatalytic degradation, reactive blue 19, TiO2 modification
Objavljeno v RUNG: 20.08.2021; Ogledov: 1476; Prenosov: 0
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Photoelectrocatalytic water splitting and dye degradation with fluorine doped tin oxides films
Manel Machreki, Takwa Chouki, Saim Emin, 2019, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: 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.
Ključne besede: FTO, thin films, dye degradation
Objavljeno v RUNG: 13.05.2021; Ogledov: 1282; Prenosov: 0
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Preparation of porous [alpha]-Fe[sub]2O[sub]3 thin films for efficient photoelectrocatalytic degradation of basic blue 41 dye
Manel Machreki, Takwa Chouki, Mitja Martelanc, Lorena Butinar, Branka Mozetič Vodopivec, Saim Emin, 2021, izvirni znanstveni članek

Opis: A novel method was developed for the preparation of porous hematite (α-Fe2O3) thin films. First, a solution containing iron precursor was spin-coated on fluorine-doped tin oxide substrate and later short heat-treated at 750 °C. The prepared α-Fe2O3 thin films were applied as dual-function catalyst in photoelectrochemical (PEC) water oxidation and textile dye degradation studies. For the first time, α-Fe2O3 thin films were used in efficient PEC degradation of a textile dye (Basic Blue 41 – B41) using in-situ generated reactive chlorine species. In comparison with photocatalytic and electrocatalytic approaches, the PEC technique allows faster degradation of B41 dye at an applied bias potential of 1.5 V versus reversible hydrogen electrode and under visible light illumination. In the presence of Cl− using the PEC approach the degradation of B41 reaches 99.8%. High-performance liquid chromatography coupled with UV–VIS system confirmed the degradation of B41 dye using PEC. Gas-chromatography coupled to mass spectrometry was used to study the by-products obtained during PEC degradation. Chemical oxygen demand analyses confirmed that the mineralization level of B41 is in the order of 68%. The α-Fe2O3 films developed in this study give a higher level of PEC degradation efficiency compared to other iron oxide-based systems.
Ključne besede: thin films, photoelectrocatalysis, kinetics, visible light, degradation, textile dye
Objavljeno v RUNG: 10.05.2021; Ogledov: 1530; Prenosov: 9
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Managing karst in Coastal British Columbia, Canada : systems and implementation results
Paul Andre Griffiths, 2020, doktorska disertacija

Opis: This thesis provides a detailed description and analysis of the system used for managing karst in the forests of coastal British Columbia (BC), where the major land- use activity is industrial forestry. In 2004, BC shifted from a more prescriptive forest management model (the Forest Practices Code) to a less regulated, results-based approach based primarily on the Forest and Range Practices Act (FRPA). The dissertation examines how this results-based management approach for forest resources has worked – or not worked – with respect to karst. The research focused on the five key realms of an environmental management system as defined by the International Standards Organization (ISO 14001 standard): 1) Legislation and Policy, 2) Planning, 3) Implementation, 4) Checking/Corrective Action, and 5) Management Review. The research also examined the roles of professional reliance (another major foundational element of the FRPA model), karst research, and organizational capacity as external factors which influence on the functioning of the karst management system. A combination of interviews, surveys, document reviews and field observations were used to collect qualitative information relevant to all aspects of the karst management system. This research reveals inadequacies in all five realms of BC’s current karst management framework, including gaps in legislation, a lack of implementation of existing standards and guidelines, and non-existent effectiveness and compliance monitoring. The results suggest that BC’s shift to ‘self-regulation’ has yielded unsatisfactory results so far for karst resources and has hindered progress toward implementing a fully integrated science-based ecosystem approach to karst management in the study area. Professional reliance failures are identified as one of the key factors contributing to a breakdown of the management system for karst. This is the first comprehensive study that examines the systems and processes used for managing karst in coastal BC, and consolidates knowledge for government, industry, and others that wish to study or better understand BC’s approach and methods for managing karst. The findings will be useful for private and public forest sector organizations endeavoring to implement fully-functional and effective systems for managing karst in a forestry context. This information may also have more specific applications for managing karst.
Ključne besede: karst ecosystems, protection and management, legislation, policies, standards and guidelines, environmental degradation, forestry impacts, professional reliance, British Columbia, Canada
Objavljeno v RUNG: 02.03.2020; Ogledov: 2844; Prenosov: 54
.pdf Celotno besedilo (136,27 MB)

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