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Context The present work provides a systematic theoretical analysis of the nature of the chemical bond in Al2O3, Ga2O3, and In2O3 group 13 cubic crystal structure metal oxides. The influence of the functional in the resulting band gap is assessed. The topological analysis of the electron density provides unambiguous information about the degree of ionicity along the group which is linearly correlated with the band gap values and with the cost of forming a single oxygen vacancy. Overall, this study offers a comprehensive insight into the electronic structure of metal oxides and their interrelations. This will help researchers to harness information effectively, boosting the development of novel metal oxide catalysts or innovative methodologies for their preparation.Methods Periodic density functional theory was used to predict the atomic structure of the materials of interest. Structure optimization was carried out using the PBE functional, using a plane wave basis set and the PAW representation of the atomic cores, using the VASP code. Next, the electronic properties were computed by carrying out single point calculations employing PBE, PBE + U functionals using VASP and also with PBE and the hybrid HSE06 functionals using the FHI-AIMS software. For the hybrid HSE06, the impact of the screening parameter, omega, and mixing parameter, alpha, on the calculated band gap has also been assessed.

Chemical warfare agents (CWAs), in particular sarin pose a severe threat to both military personnel and civilians, necessitating the development of effective and efficient methods for their decontamination. The use of small, highly dispersed metal catalysts and single atom catalysts (SACs) supported on metal oxides has been a growingly appealing solution due to their superior reactivity and efficiency for the decomposition of CWAs. However, their dynamic stability and reactivity in reaction conditions are still subject of debate and insufficiently understood due to experimental limitation. This thesis aims to reconcile these shortcomings using Density Functional Theory, ab-initio thermodynamics theorem, and microkinetic modeling to help understand: (1) the dynamic stability of these highly dispersed metal single atom and nanoparticles, and (2) understand its implication towards the catalytic activity of CWA decomposition.Firstly, DFT calculations were performed to understand sarin’s base reactivity on plain, undoped rutile titanium dioxide, r-TiO2(110). We found that DMMP is a sufficient simulant to describe the chemistry of sarin as both molecules have strong binding on titania, with low reactivity and similar barrier to decompose. We then incorporate ab atomistic thermodynamics to explore the stability of Pt single atom (SA) on anatase TiO2(101). In reducing pretreatment, we show that Pt prefers adsorbed structure, occupying the surface oxygen vacancy. Using CO as probe molecule, we showcase the dynamic behavior of the Pt single atom and its intricacies in determining the rate determining intermediates during steady state reactions that is elusive to be determined by experiments alone. We then study the reactivity of GB and DMMP on Pt SA in oxidative conditions. Pt provides the thermodynamic drive to cleave P-X bond, while lowering the barrier to do so via a unique PtO4 planar-like structure. We then briefly study the role of highly dispersed Cu4 cluster with and

Propylene is currently only produced using fossil feedstock. Due to its large production and greenhouse gas (GHG)-emissions it is vital to use a biobased feedstock to reduce the dependence on fossil resources and the impact on the climate. In this review, several different bio-based alternatives are presented. Utilizing bioethanol is further discussed where using either metal oxide or ZSM-5 as catalyst is assessed, based on its technical feasibility. Furthermore, the GHG-emissions in the process are identified and possible solutions for their elimination are suggested.

Propylene is currently only produced using fossil feedstock. Due to its large production and greenhouse gas (GHG)-emissions it is vital to use a biobased feedstock to reduce the dependence on fossil resources and the impact on the climate. In this review, several different bio-based alternatives are presented. Utilizing bioethanol is further discussed where using either metal oxide or ZSM-5 as catalyst is assessed, based on its technical feasibility. Furthermore, the GHG-emissions in the process are identified and possible solutions for their elimination are suggested.

To achieve more stable and efficient metal halide perovskite devices, optimization of charge transport materials and their interfaces with perovskites is crucial. ZnO on paper would make an ideal electron transport layer in perovskite devices. This metal oxide has a large bandgap, making it transparent to visible light; it can be easily n-type doped, has a decent electron mobility, and is thought to be chemically relatively inert. However, in combination with perovskites, ZnO has turned out to be a source of instability, rapidly degrading the performance of devices. In this work, we provide a comprehensive experimental and computational study of the interaction between the most common organic perovskite precursors and the surface of ZnO, with the aim of understanding the observed instability. Using X-ray photoelectron spectroscopy, we find a complete degradation of the precursors in contact with ZnO and the formation of volatile species as well as new surface bonds. Our computational work reveals that different pristine and defected surface terminations of ZnO facilitate the decomposition of the perovskite precursor molecules, mainly through deprotonation, making the deposition of the latter on those surfaces impossible without the use of passivation., To achieve more stable and efficient metal halide perovskite devices, optimization of charge transport materials and their interfaces with perovskites is crucial. ZnO on paper would make an ideal electron transport layer in perovskite devices. This metal oxide has a large bandgap, making it transparent to visible light; it can be easily n-type doped, has a decent electron mobility, and is thought to be chemically relatively inert. However, in combination with perovskites, ZnO has turned out to be a source of instability, rapidly degrading the performance of devices. In this work, we provide a comprehensive experimental and computational study of the interaction between the most common organic perovskite precursors and the surface of ZnO, with the aim of understanding the observed instability. Using X-ray photoelectron spectroscopy, we find a complete degradation of the precursors in contact with ZnO and the formation of volatile species as well as new surface bonds. Our computational work reveals that different pristine and defected surface terminations of ZnO facilitate the decomposition of the perovskite precursor molecules, mainly through deprotonation, making the deposition of the latter on those surfaces impossible without the use of passivation.

Ovo istraživanje ima za cilj ispitivanje efikasnosti degradacije kongo crvene boje (KC) korišćenjem metalno-organskih mrežnih struktura (MOF), metalnih oksida (MeO) i njihovih kompozita. KC se često koristi u tekstilnoj industriji, a njeno ispuštanje u životnu sredinu može imati štetne efekte na život u vodenoj sredini i ljudsko zdravlje. MOF koji je korišćen u ovom istraživanju bio je UiO-66, koji ima visoku površinu i mogućnost podešavanja veličine pora, što ga čini obećavajućim kandidatom za primene u remedijaciji životne sredine. Efikasnost uklanjanja KC ocenjena je korišćenjem UV-Vis spektroskopije. Oksidi kobalta i bakra su odabrani zbog povoljnih vrednosti njihovih energetskih procepa (1.4-2.4 eV), koje se nalaze unutar energetskog opsega zračenja vidljive svetlosti, za razliku od UiO-66 čija je vrednost energetskog procepa daleko veća (3.7-4.1 eV). Rezultati su pokazali da je Cu2O samostalno imao najmanji efekat na degradaciju KC, dok je kompozit MOF+CuO+Cu2O imao najviši procenat degradacije KC. Kompozit je degradirao 91% KC u roku od 2 sata reakcije, dok je sam MOF degradirao samo 47%. Ovo istraživanje ukazuje na mogućnost primene MOF+CuO+Cu2O i MOF+CuO kompozita, kao efikasnih katalizatora za degradaciju KC. Rezultati takođe sugerišu da bi MeO+MOF kompoziti uopšte, mogli biti efikasna alternativa za samostalnu upotrebu UiO-66 metalno-organskih mrežnih struktura u procesu uklanjanja boja u tretmanu otpadnih voda. Upotreba MOF-ova i njihovih kompozita sa metalnim oksidima može predstavljati obećavajući pristup za remedijaciju životne sredine tj. uklanjanje štetnih zagađujućih materija iz voda, doprinoseći očuvanju i zaštiti ljudskog zdravlja., This study aimed to investigate the degradation efficiency of Congo red dye using metal-organic frameworks (MOFs), metal oxides (MeOs), and their composite powders. Congo red is a commonly used dye in the textile industry and its release into the environment can have harmful effects on aquatic life and human health. MOF used in this study was UiO-66, which has a high surface area and tunable pore size, making it a promising candidate for environmental remediation applications. Removal efficiency of Congo red dye was evaluated using UV-vis spectroscopy. Cobalt and copper oxides were chosen because of their suitable band gaps (1.4-2.4 eV) which falls within the favorable band gap range for visible light absorption, contrary to the UiO-66, whose band gap is ≈3.7-4.1 eV. Results showed that Cu2O when used alone had the weakest effect on the degradation of the dye, while the composite of MOF+CuO+Cu2O had the highest percentage of dye degradation. The composite degraded 91% of the dye within 2 hours of the reaction, whereas MOF alone degraded only 47% of the dye. This study showed that MOF+CuO and MOF+CuO+Cu2O composites can be used as efficient catalysts for wastewater treatment, specifically for the degradation of Congo red dye. These findings also suggest that the MeO+MOF composites in general, could be an effective alternative to MOFs alone for the environmental remediation applications. The use of MOFs and their composites with metal oxides could provide a promising approach for the removal of harmful pollutants from wastewaters, contributing to the preservation of our environment and the protection of human health.

2023 Descuento MDPI, Tungsten oxide thin films have applications in various energy-related devices owing to their versatile semiconductor properties, which depend on the oxygen content and crystalline state. The concentration of electrons increases with intrinsic defects such as oxygen vacancies, which create new absorption bands that give rise to colored films. Disorders in the crystal structure produce additional changes in the electrical and optical characteristics. Here, WO3−x thin films are prepared on unheated glass substrates by reactive DC sputtering from a pure metal target, using the discharge power and the oxygen-to-argon pressure ratio as control parameters. A transition from amorphous to polycrystalline state is obtained by increasing the sputtering power and adjusting the oxygen content. The surface roughness is higher and the bandgap energy is lower for polycrystalline layers than for amorphous ones. Moreover, the electrical conductivity and sub-bandgap absorption increase as the oxygen content decreases., Depto. de Química Física, Fac. de Ciencias Químicas, TRUE, pub, Descuento UCM

La séparation de l'eau par la technologie photoélectrochimique (PEC) est un moyen écologique et durable de produire de l'hydrogène. Les matériaux semi-conducteurs, en tant que composants centraux des cellules de fractionnement de l'eau PEC, ont une influence décisive sur l'efficacité de la conversion solaire-hydrogène du dispositif. En tant que semi-conducteur le plus courant, l'oxyde métallique (MO) a fait l'objet d'une grande attention en raison de sa remarquable stabilité (photo)-électrochimique, de son faible coût, de la position favorable de ses bords de bande et de la large distribution de ses bandes interdites. Malgré ces caractéristiques attrayantes, son application dans la séparation de l'eau PEC souffre toujours de ses inconvénients intrinsèques, tels que le désordre et la non-uniformité, qui limitent sérieusement l'efficacité et les performances du système PEC. Cependant, les méthodes traditionnelles de synthèse de la MO ne parviennent pas à améliorer ces caractéristiques. Par conséquent, il est vraiment urgent de développer une nouvelle méthode de synthèse de MO, qui fournira facilement des architectures poreuses stables, une phase contrôlée, ainsi qu'un contrôle utile des dimensions (1-D, 2-D et 3-D) de la MO pour améliorer leurs performances et leur efficacité dans les applications de séparation de l'eau. En tant que matériaux hybrides organiques-inorganiques cristallins émergents, les cadres métallo-organiques (MOF) ont été largement utilisés comme précurseurs sacrificiels pour la synthèse de MO en raison de leurs composites aux nanostructures et compositions chimiques accordables et contrôlables. Dans cette thèse, nous avons développé un certain nombre de photoélectrodes à base de MO par la méthode du modèle MOF et évalué leurs performances dans la génération d'hydrogène par séparation d'eau PEC. Le dioxyde de titane (TiO2) est devenu l'un des semi-conducteurs MO les plus étudiés pour la séparation de l'eau PEC depuis 1972. Cependant, le c

In the last several decades, metal oxide thin films have attracted significant attention for the development of various existing and emerging technological applications, including pH sensors. The mandate for consistent and precise pH sensing techniques has been increasing across various fields, including environmental monitoring, biotechnology, food and agricultural industries, and medical diagnostics. Metal oxide thin films grown using physical vapor deposition (PVD) with precise control over film thickness, composition, and morphology are beneficial for pH sensing applications such as enhancing pH sensitivity and stability, quicker response, repeatability, and compatibility with miniaturization. Various PVD techniques, including sputtering, evaporation, and ion beam deposition, used to fabricate thin films for tailoring materials’ properties for the advanced design and development of high-performing pH sensors, have been explored worldwide by many research groups. In addition, various thin film materials have also been investigated, including metal oxides, nitrides, and nanostructured films, to make very robust pH sensing electrodes with higher pH sensing performance. The development of novel materials and structures has enabled higher sensitivity, improved selectivity, and enhanced durability in harsh pH environments. The last decade has witnessed significant advancements in PVD thin films for pH sensing applications. The combination of precise film deposition techniques, novel materials, and surface functionalization strategies has led to improved pH sensing performance, making PVD thin films a promising choice for future pH sensing technologies.

The mixing of [V10 O28 ]6- decavanadate anions with a dicationic gemini surfactant (gem) leads to the spontaneous self-assembly of surfactant-templated nanostructured arrays of decavanadate clusters. Calcination of the material under air yields highly crystalline, sponge-like V2 O5 (gem-V2 O5 ). In contrast, calcination of the amorphous tetrabutylammonium decavanadate allows isolation of a more agglomerated V2 O5 consisting of very small crystallites (TBA-V2 O5 ). Electrochemical analysis of the materials' performance as lithium-ion intercalation electrodes highlights the role of morphology in cathode performance. The large crystallites and long-range microstructure of the gem-V2 O5 cathode deliver higher initial capacity and superior capacity retention than TBA-V2 O5 . The smaller crystallite size and higher surface area of TBA-V2 O5 allow faster lithium insertion and superior rate performance to gem-V2 O5 .

[Abstract] In the last decade, TiO2 nanotubes have attracted the attention of the scientific community and industry due to their exceptional photocatalytic properties, opening a wide range of additional applications in the fields of renewable energy, sensors, supercapacitors, and the pharmaceutical industry. However, their use is limited because their band gap is tied to the visible light spectrum. Therefore, it is essential to dope them with metals to extend their physicochemical advantages. In this review, we provide a brief overview of the preparation of metal-doped TiO2 nanotubes. We address hydrothermal and alteration methods that have been used to study the effects of different metal dopants on the structural, morphological, and optoelectrical properties of anatase and rutile nanotubes. The progress of DFT studies on the metal doping of TiO2 nanoparticles is discussed. In addition, the traditional models and their confirmation of the results of the experiment with TiO2 nanotubes are reviewed, as well as the use of TNT in various applications and the future prospects for its development in other fields. We focus on the comprehensive analysis and practical significance of the development of TiO2 hybrid materials and the need for a better understanding of the structural–chemical properties of anatase TiO2 nanotubes with metal doping for ion storage devices such as batteries.

Background: Acute phase response (APR) is characterized by a change in concentration of different proteins, including C-reactive protein and serum amyloid A (SAA) that can be linked to both exposure to metal oxide nanomaterials and risk of cardiovascular diseases. In this study, we intratracheally exposed mice to ZnO, CuO, Al2O3, SnO2 and TiO2 and carbon black (Printex 90) nanomaterials with a wide range in phagolysosomal solubility. We subsequently assessed neutrophil numbers, protein and lactate dehydrogenase activity in bronchoalveolar lavage fluid, Saa3 and Saa1 mRNA levels in lung and liver tissue, respectively, and SAA3 and SAA1/2 in plasma. Endpoints were analyzed 1 and 28 days after exposure, including histopathology of lung and liver tissues. Results: All nanomaterials induced pulmonary inflammation after 1 day, and exposure to ZnO, CuO, SnO2, TiO2 and Printex 90 increased Saa3 mRNA levels in lungs and Saa1 mRNA levels in liver. Additionally, CuO, SnO2, TiO2 and Printex 90 increased plasma levels of SAA3 and SAA1/2. Acute phase response was predicted by deposited surface area for insoluble metal oxides, 1 and 28 days post-exposure. Conclusion: Soluble and insoluble metal oxides induced dose-dependent APR with different time dependency. Neutrophil influx, Saa3 mRNA levels in lung tissue and plasma SAA3 levels correlated across all studied nanomaterials, suggesting that these endpoints can be used as biomarkers of acute phase response and cardiovascular disease risk following exposure to soluble and insoluble particles., Atmospheric Remote Sensing

Background Acute phase response (APR) is characterized by a change in concentration of different proteins, including C-reactive protein and serum amyloid A (SAA) that can be linked to both exposure to metal oxide nanomaterials and risk of cardiovascular diseases. In this study, we intratracheally exposed mice to ZnO, CuO, Al2O3, SnO2 and TiO2 and carbon black (Printex 90) nanomaterials with a wide range in phagolysosomal solubility. We subsequently assessed neutrophil numbers, protein and lactate dehydrogenase activity in bronchoalveolar lavage fluid, Saa3 and Saa1 mRNA levels in lung and liver tissue, respectively, and SAA3 and SAA1/2 in plasma. Endpoints were analyzed 1 and 28 days after exposure, including histopathology of lung and liver tissues. Results All nanomaterials induced pulmonary inflammation after 1 day, and exposure to ZnO, CuO, SnO2, TiO2 and Printex 90 increased Saa3 mRNA levels in lungs and Saa1 mRNA levels in liver. Additionally, CuO, SnO2, TiO2 and Printex 90 increased plasma levels of SAA3 and SAA1/2. Acute phase response was predicted by deposited surface area for insoluble metal oxides, 1 and 28 days post-exposure. Conclusion Soluble and insoluble metal oxides induced dose-dependent APR with different time dependency. Neutrophil influx, Saa3 mRNA levels in lung tissue and plasma SAA3 levels correlated across all studied nanomaterials, suggesting that these endpoints can be used as biomarkers of acute phase response and cardiovascular disease risk following exposure to soluble and insoluble particles, Background: Acute phase response (APR) is characterized by a change in concentration of different proteins, including C-reactive protein and serum amyloid A (SAA) that can be linked to both exposure to metal oxide nanomaterials and risk of cardiovascular diseases. In this study, we intratracheally exposed mice to ZnO, CuO, Al2O3, SnO2 and TiO2 and carbon black (Printex 90) nanomaterials with a wide range in phagolysosomal solubility. We subsequently assessed neutrophil numbers, protein and lactate dehydrogenase activity in bronchoalveolar lavage fluid, Saa3 and Saa1 mRNA levels in lung and liver tissue, respectively, and SAA3 and SAA1/2 in plasma. Endpoints were analyzed 1 and 28 days after exposure, including histopathology of lung and liver tissues. Results: All nanomaterials induced pulmonary inflammation after 1 day, and exposure to ZnO, CuO, SnO2, TiO2 and Printex 90 increased Saa3 mRNA levels in lungs and Saa1 mRNA levels in liver. Additionally, CuO, SnO2, TiO2 and Printex 90 increased plasma levels of SAA3 and SAA1/2. Acute phase response was predicted by deposited surface area for insoluble metal oxides, 1 and 28 days post-exposure. Conclusion: Soluble and insoluble metal oxides induced dose-dependent APR with different time dependency. Neutrophil influx, Saa3 mRNA levels in lung tissue and plasma SAA3 levels correlated across all studied nanomaterials, suggesting that these endpoints can be used as biomarkers of acute phase response and cardiovascular disease risk following exposure to soluble and insoluble particles.

Background Acute phase response (APR) is characterized by a change in concentration of different proteins, including C-reactive protein and serum amyloid A (SAA) that can be linked to both exposure to metal oxide nanomaterials and risk of cardiovascular diseases. In this study, we intratracheally exposed mice to ZnO, CuO, Al2O3, SnO2 and TiO2 and carbon black (Printex 90) nanomaterials with a wide range in phagolysosomal solubility. We subsequently assessed neutrophil numbers, protein and lactate dehydrogenase activity in bronchoalveolar lavage fluid, Saa3 and Saa1 mRNA levels in lung and liver tissue, respectively, and SAA3 and SAA1/2 in plasma. Endpoints were analyzed 1 and 28 days after exposure, including histopathology of lung and liver tissues. Results All nanomaterials induced pulmonary inflammation after 1 day, and exposure to ZnO, CuO, SnO2, TiO2 and Printex 90 increased Saa3 mRNA levels in lungs and Saa1 mRNA levels in liver. Additionally, CuO, SnO2, TiO2 and Printex 90 increased plasma levels of SAA3 and SAA1/2. Acute phase response was predicted by deposited surface area for insoluble metal oxides, 1 and 28 days post-exposure. Conclusion Soluble and insoluble metal oxides induced dose-dependent APR with different time dependency. Neutrophil influx, Saa3 mRNA levels in lung tissue and plasma SAA3 levels correlated across all studied nanomaterials, suggesting that these endpoints can be used as biomarkers of acute phase response and cardiovascular disease risk following exposure to soluble and insoluble particles, Background: Acute phase response (APR) is characterized by a change in concentration of different proteins, including C-reactive protein and serum amyloid A (SAA) that can be linked to both exposure to metal oxide nanomaterials and risk of cardiovascular diseases. In this study, we intratracheally exposed mice to ZnO, CuO, Al2O3, SnO2 and TiO2 and carbon black (Printex 90) nanomaterials with a wide range in phagolysosomal solubility. We subsequently assessed neutrophil numbers, protein and lactate dehydrogenase activity in bronchoalveolar lavage fluid, Saa3 and Saa1 mRNA levels in lung and liver tissue, respectively, and SAA3 and SAA1/2 in plasma. Endpoints were analyzed 1 and 28 days after exposure, including histopathology of lung and liver tissues. Results: All nanomaterials induced pulmonary inflammation after 1 day, and exposure to ZnO, CuO, SnO2, TiO2 and Printex 90 increased Saa3 mRNA levels in lungs and Saa1 mRNA levels in liver. Additionally, CuO, SnO2, TiO2 and Printex 90 increased plasma levels of SAA3 and SAA1/2. Acute phase response was predicted by deposited surface area for insoluble metal oxides, 1 and 28 days post-exposure. Conclusion: Soluble and insoluble metal oxides induced dose-dependent APR with different time dependency. Neutrophil influx, Saa3 mRNA levels in lung tissue and plasma SAA3 levels correlated across all studied nanomaterials, suggesting that these endpoints can be used as biomarkers of acute phase response and cardiovascular disease risk following exposure to soluble and insoluble particles.

Biomineralization is an elaborate process that controls the deposition of inorganic materials in living organisms with the aid of associated proteins. Magnetotactic bacteria mineralize magnetite (Fe3O4) nanoparticles with finely tuned morphologies in their cells. Mms6, a magnetosome membrane specific (Mms) protein isolated from the surfaces of bacterial magnetite nanoparticles, plays an important role in regulating the magnetite crystal morphology. Although the binding ability of Mms6 to magnetite nanoparticles has been speculated, the interactions between Mms6 and magnetite crystals have not been elucidated thus far. Here, we show a direct adsorption ability of Mms6 on magnetite nanoparticles in vitro. An adsorption isotherm indicates that Mms6 has a high adsorption affinity (Kd = 9.52 µM) to magnetite nanoparticles. In addition, Mms6 also demonstrated adsorption on other inorganic nanoparticles such as titanium oxide, zinc oxide, and hydroxyapatite. Therefore, Mms6 can potentially be utilized for the bioconjugation of functional proteins to inorganic material surfaces to modulate inorganic nanoparticles for biomedical and medicinal applications.

Rapid industrial development, vehicles, domestic activities and mishandling of garbage are the main sources of pollutants, which are destroying the atmosphere. There is a need to continuously monitor these pollutants for the safety of the environment and human beings. Conventional instruments for monitoring of toxic gases are expensive, bigger in size and time-consuming. Hybrid materials containing organic and inorganic components are considered potential candidates for diverse applications, including gas sensing. Gas sensors convert the information regarding the analyte into signals. Various polymeric/inorganic nanohybrids have been used for the sensing of toxic gases. Composites of different polymeric materials like polyaniline (PANI), poly (4-styrene sulfonate) (PSS), poly (3,4-ethylene dioxythiophene) (PEDOT), etc. with various metal/metal oxide nanoparticles have been reported as sensing materials for gas sensors because of their unique redox features, conductivity and facile operation at room temperature. Polymeric nanohybrids showed better performance because of the larger surface area of nanohybrids and the synergistic effect between polymeric and inorganic materials. This review article focuses on the recent developments of emerging polymeric/inorganic nanohybrids for sensing various toxic gases including ammonia, hydrogen, nitrogen dioxide, carbon oxides and liquefied petroleum gas. Advantages, disadvantages, operating conditions and prospects of hybrid composites have also been discussed., Rivers, Ports, Waterways and Dredging Engineering, Hydraulic Engineering, Aerospace Manufacturing Technologies

Despite the rapid progress in perovskite solar cells, their commercialization is still hindered by issues regarding long-term stability, which can be strongly affected by metal oxide-based charge extraction layers next to the perovskite material. With MoO3 being one of the most successful hole transport layers in organic photovoltaics, the disastrous results of its combination with perovskite films came as a surprise but was soon attributed to severe chemical instability at the MoO3/perovskite interface. To discover the atomistic origin of this instability, we combine density functional theory (DFT) calculations and X-ray photoelectron spectroscopy (XPS) measurements to investigate the interaction of MoO3 with the perovskite precursors MAI, MABr, FAI, and FABr. From DFT calculations we suggest a scenario that is based upon oxygen vacancies playing a key role in interface degradation reactions. Not only do these vacancies promote decomposition reactions of perovskite precursors, but they also constitute the reaction centers for redox reactions leading to oxidation of the halides and reduction of Mo. Specifically iodides are proposed to be reactive, while bromides do not significantly affect the oxide. XPS measurements reveal a severe reduction of Mo and a loss of the halide species when the oxide is interfaced with I-containing precursors, which is consistent with the proposed scenario. In line with the latter, experimentally observed effects are much less pronounced in case of Br-containing precursors. We further find that the reactivity of the MoO3 substrate can be moderated by reducing the number of oxygen vacancies through a UV/ozone treatment, though it cannot be fully eliminated.

For gas sensing applications, metal oxide (MOx) nanostructures have demonstrated attractive properties due their large surface-over-volume ratio, combined with the possibility to use multiple materials and multi-functional properties. For MOx chemiresistive gas sensors, the temperature activated interaction of atmospheric oxygen with MOx surface plays a major role in the sensor kinetics as it leads to oxygen adsorption-desorption reactions, that eventually affects the gas sensing performance. Thus, MOx sensors are operated at high temperatures to achieve the desired sensitivity. This high temperature operation of MOx sensors limits their application in explosive gas detection, reduces the sensor lifetime and causes power consumption. To overcome these drawbacks of MOx sensors, researchers have proposed the use of heterostructures and light activation as alternatives. In this thesis, we aim to develop low power consuming MOx sensors using these solutions. We show the template-free bottom-up synthesis and shape control of copper hydroxide-based nanostructures grown in liquid phase which act as templates for formation of CuO nanostructures. Precise control over the pH of the solution and the reaction temperature led to intended tuning of the morphology and chemical composition of the nanostructures. We contemplate upon the rationale behind this change in shape and material as CuO nanostructures are further used in a heterostructure. We discuss synthesis and characterisation of CuO bundles and Cu2O truncated cubes, former of which lead to very interesting gas sensing properties and application. Devices made from CuO bundles network are investigated for their electrical and oxygen adsorption- desorption properties as a gas sensor. It was observed that the sensor has faster response and recovery in as deposited condition in comparison to annealed sensor. A detailed inspection of response and recovery curves enabled us to derive parameters like time constants, reaction con

For gas sensing applications, metal oxide (MOx) nanostructures have demonstrated attractive properties due their large surface-over-volume ratio, combined with the possibility to use multiple materials and multi-functional properties. For MOx chemiresistive gas sensors, the temperature activated interaction of atmospheric oxygen with MOx surface plays a major role in the sensor kinetics as it leads to oxygen adsorption-desorption reactions, that eventually affects the gas sensing performance. Thus, MOx sensors are operated at high temperatures to achieve the desired sensitivity. This high temperature operation of MOx sensors limits their application in explosive gas detection, reduces the sensor lifetime and causes power consumption. To overcome these drawbacks of MOx sensors, researchers have proposed the use of heterostructures and light activation as alternatives. In this thesis, we aim to develop low power consuming MOx sensors using these solutions. We show the template-free bottom-up synthesis and shape control of copper hydroxide-based nanostructures grown in liquid phase which act as templates for formation of CuO nanostructures. Precise control over the pH of the solution and the reaction temperature led to intended tuning of the morphology and chemical composition of the nanostructures. We contemplate upon the rationale behind this change in shape and material as CuO nanostructures are further used in a heterostructure. We discuss synthesis and characterisation of CuO bundles and Cu2O truncated cubes, former of which lead to very interesting gas sensing properties and application. Devices made from CuO bundles network are investigated for their electrical and oxygen adsorption- desorption properties as a gas sensor. It was observed that the sensor has faster response and recovery in as deposited condition in comparison to annealed sensor. A detailed inspection of response and recovery curves enabled us to derive parameters like time constants, reaction con

QC 20230524

One can nowadays readily generate monodisperse colloidal nanocrystals, but a retrosynthetic analysis is still not possible since the underlying chemistry is often poorly understood. Here, we provide insight into the reaction mechanism of colloidal zirconia and hafnia nanocrystals synthesized from metal chloride and metal isopropoxide. We identify the active precursor species in the reaction mixture through a combination of nuclear magnetic resonance spectroscopy (NMR), density functional theory (DFT) calculations, and pair distribution function (PDF) analysis. We gain insight into the interaction of the surfactant, tri-n-octylphosphine oxide (TOPO), and the different precursors. Interestingly, we identify a peculiar X-type ligand redistribution mechanism that can be steered by the relative amount of Lewis base (L-type). We further monitor how the reaction mixture decomposes using solution NMR and gas chromatography, and we find that ZrCl4is formed as a by-product of the reaction, limiting the reaction yield. The reaction proceeds via two competing mechanisms: E1 elimination (dominating) and SN1 substitution (minor). Using this new mechanistic insight, we adapted the synthesis to optimize the yield and gain control over nanocrystal size. These insights will allow the rational design and synthesis of complex oxide nanocrystals.

Despite the rapid progress in perovskite solar cells, their commercialization is still hindered by issues regarding long-term stability, which can be strongly affected by metal oxide-based charge extraction layers next to the perovskite material. With MoO3 being one of the most successful hole transport layers in organic photovoltaics, the disastrous results of its combination with perovskite films came as a surprise but was soon attributed to severe chemical instability at the MoO3/perovskite interface. To discover the atomistic origin of this instability, we combine density functional theory (DFT) calculations and X-ray photoelectron spectroscopy (XPS) measurements to investigate the interaction of MoO3 with the perovskite precursors MAI, MABr, FAI, and FABr. From DFT calculations we suggest a scenario that is based upon oxygen vacancies playing a key role in interface degradation reactions. Not only do these vacancies promote decomposition reactions of perovskite precursors, but they also constitute the reaction centers for redox reactions leading to oxidation of the halides and reduction of Mo. Specifically iodides are proposed to be reactive, while bromides do not significantly affect the oxide. XPS measurements reveal a severe reduction of Mo and a loss of the halide species when the oxide is interfaced with I-containing precursors, which is consistent with the proposed scenario. In line with the latter, experimentally observed effects are much less pronounced in case of Br-containing precursors. We further find that the reactivity of the MoO3 substrate can be moderated by reducing the number of oxygen vacancies through a UV/ozone treatment, though it cannot be fully eliminated.

Rapid industrial development, vehicles, domestic activities and mishandling of garbage are the main sources of pollutants, which are destroying the atmosphere. There is a need to continuously monitor these pollutants for the safety of the environment and human beings. Conventional instruments for monitoring of toxic gases are expensive, bigger in size and time-consuming. Hybrid materials containing organic and inorganic components are considered potential candidates for diverse applications, including gas sensing. Gas sensors convert the information regarding the analyte into signals. Various polymeric/inorganic nanohybrids have been used for the sensing of toxic gases. Composites of different polymeric materials like polyaniline (PANI), poly (4-styrene sulfonate) (PSS), poly (3,4-ethylene dioxythiophene) (PEDOT), etc. with various metal/metal oxide nanoparticles have been reported as sensing materials for gas sensors because of their unique redox features, conductivity and facile operation at room temperature. Polymeric nanohybrids showed better performance because of the larger surface area of nanohybrids and the synergistic effect between polymeric and inorganic materials. This review article focuses on the recent developments of emerging polymeric/inorganic nanohybrids for sensing various toxic gases including ammonia, hydrogen, nitrogen dioxide, carbon oxides and liquefied petroleum gas. Advantages, disadvantages, operating conditions and prospects of hybrid composites have also been discussed., Rivers, Ports, Waterways and Dredging Engineering, Hydraulic Engineering, Aerospace Manufacturing Technologies

Heart and Stroke Foundation South Africa (HSFSA) reports that about 17.3% of deaths in the country are associated with heart-related diseases and this rate is expected to increase to 41% by the year 2030. This severe increase in death cases is related to diseases caused by consumption of meat (i.e., pork, fish, red meat, and poultry) with high levels of hypoxanthine. Therefore, this raises the need to investigate and detect hypoxanthine levels in the meat. This study aimed at developing a highly stable and sensitive biosensor for the detection of hypoxanthine in fish meat using the glassy carbon electrode (GCE) modified with carbon nanocomposites materials (consisting of metal oxides doped multi-walled carbon nanotubes (MO-MWCNTs) that are treated with amine groups) and an enzyme, xanthine oxidase (XOD) as a catalyst. The sol gel method was used to prepare the metal oxides including zinc oxide (ZnO), zirconium dioxide (ZrO2), manganese (MnO2), cobalt oxide (Co3O4), and titanium dioxide (TiO2). The in-situ method of functionalisation of MWCNTs was employed to increase their current outputs/sensitivity using selected amines, namely, methylenediamine, hydrazine, ethylenediamine (EDA), and triethylenetetramine (TETA). The electrochemical properties of the metal oxides and amine functionalised MWCNTs were studied using both cyclic and differential pulse voltammetry. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of carboxyl (COOH), hydroxyl (OH), and amino (NH2) groups on the surface of the modified MWCNTs; as well as formation of stretching vibrations which appear at lower wavelengths due to the metallic species within the nanocomposite. Thermal gravimetric analyser (TGA) was employed to determine the thermal stability of the nanocomposite. Scanning electron microscopy (SEM) was used to confirm the composite structure and correct deposition of the metal oxides on the walls of MWCNTs. XRD was used to confirm correct structure formation, the crystal, National Research Foundation (NRF) and Sasol Inzalo Foundation

One can nowadays readily generate monodisperse colloidal nanocrystals, but a retrosynthetic analysis is still not possible since the underlying chemistry is often poorly understood. Here, we provide insight into the reaction mechanism of colloidal zirconia and hafnia nanocrystals synthesized from metal chloride and metal isopropoxide. We identify the active precursor species in the reaction mixture through a combination of nuclear magnetic resonance spectroscopy (NMR), density functional theory (DFT) calculations, and pair distribution function (PDF) analysis. We gain insight into the interaction of the surfactant, tri-n-octylphosphine oxide (TOPO), and the different precursors. Interestingly, we identify a peculiar X-type ligand redistribution mechanism that can be steered by the relative amount of Lewis base (L-type). We further monitor how the reaction mixture decomposes using solution NMR and gas chromatography, and we find that ZrCl4is formed as a by-product of the reaction, limiting the reaction yield. The reaction proceeds via two competing mechanisms: E1 elimination (dominating) and SN1 substitution (minor). Using this new mechanistic insight, we adapted the synthesis to optimize the yield and gain control over nanocrystal size. These insights will allow the rational design and synthesis of complex oxide nanocrystals.

In this paper, we have investigated undoped and indium-doped titanium dioxide (TiO2) nanoparticles prepared using sol–gel method. The aim of this work is to analyse the effect of indium incorporation on the structure and morphology of the materials. X-ray diffraction (XRD) pattern reveals a significant influence of In-doping on crystallinity and average grain size of the TiO2 nanoparticles. The morphology of the nanoparticles analysed using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images confirms the formation of spherical- and triangular-shaped nanoparticles with large surface area. Further, study of TEM images confirmed the obtained XRD results. Moreover, X-ray photoelectron spectroscopy (XPS) and electron diffraction spectroscopy (EDS) approve the electronic states and composition of all different chemicals existing in the samples. All the results are found and verified with the literature.

There is a great need in the biomedical field to efficiently, and cost-effectively, deliver membrane-impermeable molecules into the cellular cytoplasm. However, the cell membrane is a selectively permeable barrier, and large molecules often cannot pass through the phospholipid bilayer. We show that nanosecond laser-activated polymer surfaces of commercial polyvinyl tape and black polystyrene Petri dishes can transiently permeabilize cells for high-throughput, diverse cargo delivery of sizes of up to 150 kDa. The polymer surfaces are biocompatible and support normal cell growth of adherent cells. We determine the optimal irradiation conditions for poration, influx of fluorescent molecules into the cell, and post-treatment viability of the cells. The simple and low-cost substrates we use have no thin-metal structures, do not require cleanroom fabrication, and provide spatial selectivity and scalability for biomedical applications.

Metal oxides are a class of materials that have been widely studied for energy storage applications because of their unique physical and chemical properties. Many metal oxides play an important role in electrochemical devices. For instance, lithium cobalt oxide (LCO) and lithium iron phosphate oxide (LFP) now have been commercialized as cathode materials in lithium ion batteries (LIBs). However, there are still significant challenges in balancing the activity and stability of metal oxide based electrodes for high-performance, long life LIBs. In this thesis, four different metal oxides were investigated for the application of LIBs. Tetragonal anatase TiO2 and cubic perovskite strontium titanate (STO) nanoparticles with small diameters (≤ 20 nm) were used as coating materials to develop composites with NMC and LNMO cathodes respectively. Structurally and chemically stable STO and TiO2 nanoparticles have significantly improved battery performance regarding capacity and stability. At 1C, 5 wt.% TiO2-coated NMC 811 exhibited 16.7% higher initial discharge capacity than the pristine NMC 811; 10 wt.% STO-coated LNMO showed 24.4% higher initial discharge capacity and 19.0% higher Coulombic efficiency than the pristine LNMO.Lithium titanate (LTO) nanoparticles with different levels of oxygen vacancy were synthesized. Battery testing and computational simulation were employed to investigate the relationship between oxygen vacancy and electrochemical behaviors of LTO nano-anodes. A threshold concentration of oxygen vacancy (~7%) was found regarding performance improvement of LTO anodes. Lithium lanthanum titanate (LLTO) nanoparticles were synthesized to produce free-standing LLTO solid-state electrolytes. LLTO particles were then mixed with LTO particles to form composite anodes. Battery performance showed that the composite anodes exhibited 4.9% higher initial capacity and 6% higher Coulombic efficiency than pristine LTO anodes.In summary, TiO2 and related three types of tita

Molybdenum disulfide (MoS2) features a band gap of 1.3 eV (indirect) to 1.9 eV (direct). This tunable band gap renders MoS2 a suitable conducting channel for field-effect transistors (FETs). In addition, the highly sensitive surface potential in MoS2 layers allows the feasibility of FET applications in biosensors, where direct immobilization and detection of biological molecules are conducted in wet conditions. In this work, we report, for the first time, the degradation of chemical vapor deposition (CVD) grown MoS2 FET-based sensors in the presence of phosphate buffer and water, which caused false positive response in detection. We conclude the degradation was originated by physical delamination of MoS2 thin films from the SiO2 substrate. The problem was alleviated by coating the sensors with a 30 nm thick aluminum oxide (Al2O3) layer using atomic layer deposition technique (ALD). This passive oxide thin film not only acted as a protecting layer against the device degradation but also induced a strong n-doping onto MoS2, which permitted a facile method of detection in MoS2 FET-based sensors using a low-power mode chemiresistive I-V measurement at zero gate voltage (Vgate = 0 V). Additionally, the oxide layer provided available sites for facile functionalization with bioreceptors. As immunoreaction plays a key role in clinical diagnosis and environmental analysis, our work presented a promising application using such enhanced Al2O3-coated MoS2 chemiresistive biosensors for detection of HIgG with high sensitivity and selectivity. The biosensor was successfully applied to detect HIgG in artificial urine, a complex matrix containing organics and salts.

Amorphous metal nanoparticles (A-NPs) have aroused great interest in their structural disordering nature and combined downsizing strategies (e.g. nanoscaling), both of which are beneficial for highly strengthened properties compared to their crystalline counterparts. Conventional synthesis strategies easily induce product contamination and/or size limitations, which largely narrow their applications. In recent years, laser ablation in liquid (LAL) and laser fragmentation in liquid (LFL) as "green"and scalable colloid synthesis methodologies have attracted extensive enthusiasm in the production of ultrapure crystalline NPs, while they also show promising potential for the production of A-NPs. Yet, the amorphization in such methods still lacks sufficient rules to follow regarding the formation mechanism and criteria. To that end, this article reviews amorphous metal oxide and carbide NPs from LAL and LFL in terms of NP types, liquid selection, target elements, laser parameters, and possible formation mechanism, all of which play a significant role in the competitive relationship between amorphization and crystallization. Furthermore, we provide the prospect of laser-generated metallic glass nanoparticles (MG-NPs) from MG targets. The current and potential applications of A-NPs are also discussed, categorized by the attractive application fields e.g. in catalysis and magnetism. The present work aims to give possible selection rules and perspective on the design of colloidal A-NPs as well as the synthesis criteria of MG-NPs from laser-based strategies.

Diesel exhaust particles (DEPs) and non-exhaust particles from abrasion are two main representative sources of air pollution to which humans are exposed daily, together with emerging nanomaterials, whose emission is increasing considerably. In the present work, we aimed to investigate whether DEPs, metal oxide nanoparticles (MeO-NPs), and their mixtures could affect alveolar cells. The research was focused on whether NPs induced different types of death in cells, and on their effects on cell motility and migration. Autophagy and cell cycles were investigated via cytofluorimetric analyses, through the quantification of the autophagic biomarker LC3B and PI staining, respectively. Cellular ultrastructures were then observed via TEM. Changes in cell motility and migration were assessed via transwell migration assay, and by the cytofluorimetric analysis of E-cadherin expression. A colony-forming efficiency (CFE) assay was performed in order to investigate the interactions between cells inside the colonies, and to see how these interactions change after exposure to the single particles or their mixtures. The results obtained suggest that NPs can either reduce the toxicity of DEPs (CuO) or enhance it (ZnO), through a mechanism that may involve autophagy as cells’ response to stressors and as a consequence of particles’ cellular uptake. Moreover, NPs can induce modification of E-cadherin expression and, consequentially, of colonies’ phenotypes.

Diese Arbeit konzentriert sich auf die Charakterisierung der elektrischen und thermoelektrischen Eigenschaften zwischen T<50 K und Raumtemperatur mittels elektrischer Transportmessungen. Für ZnGa2O4 werden zusätzlich die thermischen Eigenschaften untersucht. Für die Herstellung von elektrischen Bauelementen in der Halbleiterindustrie sind dünne epitaktische Schichten von besonderem Interesse und werden daher hier für ß−Ga2O3 systematisch studiert. Dabei wird zwischen Schichtdicken von d = 25 bis 225 nm unterschieden und die Resultate mit Volumenkristallen verglichen. Für ZnGa2O4 werden erste Untersuchungen an Einkristallen durchgeführt. Für diese Arbeit wird eine neue Messplattform entwickelt, um die elektrischen und thermoelektrischen Eigenschaften charakterisieren zu können. Die Probenprozessierung wird mittels optischer Lithographie, Magnetron-Sputtern und Lift-Off umgesetzt. Für ß−Ga2O3 wird untersucht, welchen Einfluss das Wachstum und die Schichtdicke auf die elektrischen und thermoelektrischen Eigenschaften hat. Durch nicht perfektes Wachstum der Kristalle entstehen zweidimensionale Gitterfehler wodurch die Beweglichkeit ab und der Betrag des Seebeck-Koeffizienten zunimmt. Zusätzlich ist das Wachstum schichtdickenabhängig. Dünne Schichten weisen mehr null- und zweidimensionale Defekte auf, was zu einer Abnahme der Beweglichkeit führt. Durch das Studium der Streuprozesse im ß−Ga2O3 wird eine Aufteilung des Seebeck- Koeffizienten in den thermodiffusiven und Phonon-Drag-Anteil durchgeführt. Für dünne Schichten (d<100 nm) nimmt der Phonon-Drag-Parameter bei T<150 K mit abnehmender Schichtdicke um eine Größenordnung zu, was für eine Zunahme der Phonon-Phonon- zu Elektron-Phonon-Streuzeit spricht. Erste Messungen an ZnGa2O4-Volumenmaterial zeigen, dass es sich um einen entarteten Halbleiter handelt. Der Seebeck-Koeffizient zeigt ebenfalls den Phonon-Drag-Effekt mit einem Maximum bei 60 K. Die Wärmeleitfähigkeit bei Raumtemperatur ist lambda=(22.9 ± 0.2) W/mK., This work focuses on the characterization of the electric and thermoelectric transport properties between T<50 K and room temperature using electrical transport measurements. Furthermore the thermal transport properties of ZnGa2O4 are investigated. For the manufacturing of electrical devices in the semiconductor industry thin epitaxial films are of interest, hence they are studied extensively here for ß-Ga2O3. The film thicknesses are varied between d = 25 and 225 nm and their properties are compared to those of bulk material. For ZnGa2O4 first investigations are carried out on bulk material. For this work, a novel measurement platform is developed to perform the electric and thermoelectric characterization. The processing of the samples includes photolithography, magnetron sputtering and lift-off. The influence of the growth and film thickness of ß−Ga2O3 on the electric and thermoelectric properties is studied. Due to non-perfect growth of the crystals twodimensional defects are formed, which decrease the mobility and increase the absolute value of the Seebeck-coefficient. Additionally the growth depends on the film thickness. Very thin films exhibit more zero- and twodimensional defects, which decrease the mobility. The knowledge of the scattering mechanisms in ß−Ga2O3 allow a splitting of the Seebeck coefficient into the thermodiffusive and Phonon-Drag-part. For thin films (d<100 nm) and T<150 K the Phonon-Drag-parameter increases by an order of magnitude, which is explained by an increase of phonon-phonon- to electron-phonon-scattering times. First measurements of ZnGa2O4-bulk material show, that it is a degenerate semiconductor. The Seebeck-coefficient shows the Phonon-Drag-effect as well, with a maximum at 60 K. The thermal conductivity at room temperature is lambda= (22.9 ± 0.2) W/mK.

Metal-support interactions have been widely utilized for optimizing the catalytic reactivity of oxide-supported Au nanoparticles. Optimized reactivity was mainly detected with small (1-5 nm) oxide-supported Au nanoparticles and correlated to highly reactive sites at the oxide-metal interface. However, catalytically active sites are not necessarily restricted to the interface but reside as well on the Au surface. Uncovering the interconnection between reactive sites located at the interface and those situated at the metal surface is of crucial importance for understanding the reaction mechanism on Au nanoparticles. Herein, high-spatial-resolution IR nanospectroscopy measurements were conducted to map the localized reactivity in hydrogenation reactions on oxide-supported Au particles while using nitro-functionalized ligands as probes molecules. Comparative analysis of the reactivity pattern on single particles supported on various oxides revealed that oxide-dependent reactivity enhancement was not limited to the oxide-metal interface but was detected throughout the Au particle, leading to site-independent reactivity. These results indicate that reactive Au sites on both the oxide-metal interface and metal surface can activate the nitro groups toward hydrogenation reactions. The observed influence of oxide support (TiO2 > SiO2 > Al2O3) on the overall reactivity pattern specified that hydrogen dissociation occurred at the oxide-metal interface, followed by highly efficient intraparticle hydrogen atom diffusion to the interior parts of the Au particle. In contrast to Au particles, the oxide-metal interface had only a minor impact on the reactivity of supported Pt particles in which hydrogen dissociation and nitro group reduction were effectively activated on Pt sites. Single-particle measurements provided insights into the relative reactivity pattern of oxide-supported Au particles, revealing that the less-reactive Au metal sites can activate hydrogenation reaction

Molybdenum disulfide (MoS2) features a band gap of 1.3 eV (indirect) to 1.9 eV (direct). This tunable band gap renders MoS2 a suitable conducting channel for field-effect transistors (FETs). In addition, the highly sensitive surface potential in MoS2 layers allows the feasibility of FET applications in biosensors, where direct immobilization and detection of biological molecules are conducted in wet conditions. In this work, we report, for the first time, the degradation of chemical vapor deposition (CVD) grown MoS2 FET-based sensors in the presence of phosphate buffer and water, which caused false positive response in detection. We conclude the degradation was originated by physical delamination of MoS2 thin films from the SiO2 substrate. The problem was alleviated by coating the sensors with a 30 nm thick aluminum oxide (Al2O3) layer using atomic layer deposition technique (ALD). This passive oxide thin film not only acted as a protecting layer against the device degradation but also induced a strong n-doping onto MoS2, which permitted a facile method of detection in MoS2 FET-based sensors using a low-power mode chemiresistive I-V measurement at zero gate voltage (Vgate = 0 V). Additionally, the oxide layer provided available sites for facile functionalization with bioreceptors. As immunoreaction plays a key role in clinical diagnosis and environmental analysis, our work presented a promising application using such enhanced Al2O3-coated MoS2 chemiresistive biosensors for detection of HIgG with high sensitivity and selectivity. The biosensor was successfully applied to detect HIgG in artificial urine, a complex matrix containing organics and salts.

Metal-support interactions have been widely utilized for optimizing the catalytic reactivity of oxide-supported Au nanoparticles. Optimized reactivity was mainly detected with small (1-5 nm) oxide-supported Au nanoparticles and correlated to highly reactive sites at the oxide-metal interface. However, catalytically active sites are not necessarily restricted to the interface but reside as well on the Au surface. Uncovering the interconnection between reactive sites located at the interface and those situated at the metal surface is of crucial importance for understanding the reaction mechanism on Au nanoparticles. Herein, high-spatial-resolution IR nanospectroscopy measurements were conducted to map the localized reactivity in hydrogenation reactions on oxide-supported Au particles while using nitro-functionalized ligands as probes molecules. Comparative analysis of the reactivity pattern on single particles supported on various oxides revealed that oxide-dependent reactivity enhancement was not limited to the oxide-metal interface but was detected throughout the Au particle, leading to site-independent reactivity. These results indicate that reactive Au sites on both the oxide-metal interface and metal surface can activate the nitro groups toward hydrogenation reactions. The observed influence of oxide support (TiO2 > SiO2 > Al2O3) on the overall reactivity pattern specified that hydrogen dissociation occurred at the oxide-metal interface, followed by highly efficient intraparticle hydrogen atom diffusion to the interior parts of the Au particle. In contrast to Au particles, the oxide-metal interface had only a minor impact on the reactivity of supported Pt particles in which hydrogen dissociation and nitro group reduction were effectively activated on Pt sites. Single-particle measurements provided insights into the relative reactivity pattern of oxide-supported Au particles, revealing that the less-reactive Au metal sites can activate hydrogenation reaction

In this study, activated carbon-supported Sn and Zn oxide catalysts were prepared from hydrolysis lignin and used for the conversion of model solutions of trioses, hexoses, and lignocellulosic biomass hydrolysates to ethyl lactate. Both catalysts, SnO₂@AC and ZnO@AC, were able to produce ethyl lactate in high yields. SnO₂@AC was a more active and selective catalyst in triose (dihydroxyacetone) conversion, providing 99% yield to ethyl lactate. ZnO@AC, by contrast, was more selective in glucose and hydrolysate conversion, with a yield of 60% and 85%, respectively. The ethyl lactate yields were significantly higher than those from the optimized model solution experiments when using ZnO@AC catalyst. These findings indicate that milder acidity of the ZnO@AC catalyst together with Na⁺ and SO₄²⁻ in hydrolysate favored ethyl lactate production, preventing byproduct, furan derivatives and acetal, formation. Moreover, the catalysts were able to maintain their catalytic activity in recycling experiments.

In this study, heterogeneous biomass-based activated carbon-supported metal oxide catalysts were prepared and tested for lactic acid production from glucose in aqueous solution. Activated carbons were produced from hydrolysis lignin by chemical (ZnCl₂) or steam activation and modified with a nitric acid treatment and Sn, Al, and Cr chlorides to obtain carbon-based metal oxide catalysts. The modification of the carbon support by nitric acid treatment together with Sn and Al oxides led to an increase in lactic acid yield. The highest lactic acid yield (42 %) was obtained after 20 min at 180 °C with the Sn/Al (5/2.5 wt.%) catalyst on steam-activated carbon treated by nitric acid. Reusability of the catalyst was also studied with the conclusion that the deposition of carbonaceous byproducts and leaching of Al oxides led to a decrease in catalyst selectivity to lactic acid.

Amorphous metal nanoparticles (A-NPs) have aroused great interest in their structural disordering nature and combined downsizing strategies (e.g. nanoscaling), both of which are beneficial for highly strengthened properties compared to their crystalline counterparts. Conventional synthesis strategies easily induce product contamination and/or size limitations, which largely narrow their applications. In recent years, laser ablation in liquid (LAL) and laser fragmentation in liquid (LFL) as "green"and scalable colloid synthesis methodologies have attracted extensive enthusiasm in the production of ultrapure crystalline NPs, while they also show promising potential for the production of A-NPs. Yet, the amorphization in such methods still lacks sufficient rules to follow regarding the formation mechanism and criteria. To that end, this article reviews amorphous metal oxide and carbide NPs from LAL and LFL in terms of NP types, liquid selection, target elements, laser parameters, and possible formation mechanism, all of which play a significant role in the competitive relationship between amorphization and crystallization. Furthermore, we provide the prospect of laser-generated metallic glass nanoparticles (MG-NPs) from MG targets. The current and potential applications of A-NPs are also discussed, categorized by the attractive application fields e.g. in catalysis and magnetism. The present work aims to give possible selection rules and perspective on the design of colloidal A-NPs as well as the synthesis criteria of MG-NPs from laser-based strategies.

Diese Arbeit konzentriert sich auf die Charakterisierung der elektrischen und thermoelektrischen Eigenschaften zwischen T<50 K und Raumtemperatur mittels elektrischer Transportmessungen. Für ZnGa2O4 werden zusätzlich die thermischen Eigenschaften untersucht. Für die Herstellung von elektrischen Bauelementen in der Halbleiterindustrie sind dünne epitaktische Schichten von besonderem Interesse und werden daher hier für ß−Ga2O3 systematisch studiert. Dabei wird zwischen Schichtdicken von d = 25 bis 225 nm unterschieden und die Resultate mit Volumenkristallen verglichen. Für ZnGa2O4 werden erste Untersuchungen an Einkristallen durchgeführt. Für diese Arbeit wird eine neue Messplattform entwickelt, um die elektrischen und thermoelektrischen Eigenschaften charakterisieren zu können. Die Probenprozessierung wird mittels optischer Lithographie, Magnetron-Sputtern und Lift-Off umgesetzt. Für ß−Ga2O3 wird untersucht, welchen Einfluss das Wachstum und die Schichtdicke auf die elektrischen und thermoelektrischen Eigenschaften hat. Durch nicht perfektes Wachstum der Kristalle entstehen zweidimensionale Gitterfehler wodurch die Beweglichkeit ab und der Betrag des Seebeck-Koeffizienten zunimmt. Zusätzlich ist das Wachstum schichtdickenabhängig. Dünne Schichten weisen mehr null- und zweidimensionale Defekte auf, was zu einer Abnahme der Beweglichkeit führt. Durch das Studium der Streuprozesse im ß−Ga2O3 wird eine Aufteilung des Seebeck- Koeffizienten in den thermodiffusiven und Phonon-Drag-Anteil durchgeführt. Für dünne Schichten (d<100 nm) nimmt der Phonon-Drag-Parameter bei T<150 K mit abnehmender Schichtdicke um eine Größenordnung zu, was für eine Zunahme der Phonon-Phonon- zu Elektron-Phonon-Streuzeit spricht. Erste Messungen an ZnGa2O4-Volumenmaterial zeigen, dass es sich um einen entarteten Halbleiter handelt. Der Seebeck-Koeffizient zeigt ebenfalls den Phonon-Drag-Effekt mit einem Maximum bei 60 K. Die Wärmeleitfähigkeit bei Raumtemperatur ist lambda=(22.9 ± 0.2) W/mK., This work focuses on the characterization of the electric and thermoelectric transport properties between T<50 K and room temperature using electrical transport measurements. Furthermore the thermal transport properties of ZnGa2O4 are investigated. For the manufacturing of electrical devices in the semiconductor industry thin epitaxial films are of interest, hence they are studied extensively here for ß-Ga2O3. The film thicknesses are varied between d = 25 and 225 nm and their properties are compared to those of bulk material. For ZnGa2O4 first investigations are carried out on bulk material. For this work, a novel measurement platform is developed to perform the electric and thermoelectric characterization. The processing of the samples includes photolithography, magnetron sputtering and lift-off. The influence of the growth and film thickness of ß−Ga2O3 on the electric and thermoelectric properties is studied. Due to non-perfect growth of the crystals twodimensional defects are formed, which decrease the mobility and increase the absolute value of the Seebeck-coefficient. Additionally the growth depends on the film thickness. Very thin films exhibit more zero- and twodimensional defects, which decrease the mobility. The knowledge of the scattering mechanisms in ß−Ga2O3 allow a splitting of the Seebeck coefficient into the thermodiffusive and Phonon-Drag-part. For thin films (d<100 nm) and T<150 K the Phonon-Drag-parameter increases by an order of magnitude, which is explained by an increase of phonon-phonon- to electron-phonon-scattering times. First measurements of ZnGa2O4-bulk material show, that it is a degenerate semiconductor. The Seebeck-coefficient shows the Phonon-Drag-effect as well, with a maximum at 60 K. The thermal conductivity at room temperature is lambda= (22.9 ± 0.2) W/mK.

This work reports a method to reduce the process thermal budget in metal oxide (MO) thin-film transistors (TFTs). Using the thermal curing of a fluorinated polyimide planarization (PLN) layer as an efficient device activation process, this method eliminates the need for additional annealing steps before the existing PLN process in the fabrication. Bottom-gated TFTs with indium tin oxide (ITO)-stabilized ZnO channels were fabricated by this method and exhibited improved electrical characteristics over control devices made with a higher thermal budget. A steep subthreshold swing of 82.8 mV/decade and a high on-off ratio of 1.3×1010 were achieved. This improvement can be attributed to the fluorine diffusion from the PLN layer to the MO channels during the curing step. This method is useful for the cost-effective production of active-matrix flat-panel display (AM-FPD) panels and the implementation of MO TFTs on flexible substrates. IEEE

Diesel exhaust particles (DEPs) and non-exhaust particles from abrasion are two main representative sources of air pollution to which humans are exposed daily, together with emerging nanomaterials, whose emission is increasing considerably. In the present work, we aimed to investigate whether DEPs, metal oxide nanoparticles (MeO-NPs), and their mixtures could affect alveolar cells. The research was focused on whether NPs induced different types of death in cells, and on their effects on cell motility and migration. Autophagy and cell cycles were investigated via cytofluorimetric analyses, through the quantification of the autophagic biomarker LC3B and PI staining, respectively. Cellular ultrastructures were then observed via TEM. Changes in cell motility and migration were assessed via transwell migration assay, and by the cytofluorimetric analysis of E-cadherin expression. A colony-forming efficiency (CFE) assay was performed in order to investigate the interactions between cells inside the colonies, and to see how these interactions change after exposure to the single particles or their mixtures. The results obtained suggest that NPs can either reduce the toxicity of DEPs (CuO) or enhance it (ZnO), through a mechanism that may involve autophagy as cells’ response to stressors and as a consequence of particles’ cellular uptake. Moreover, NPs can induce modification of E-cadherin expression and, consequentially, of colonies’ phenotypes.

Power transmission over long distances by using high voltage direct current (HVDC) cables is important for the transition from fossil energy to using renewable energy sources, e.g. wind, solar and water. Higher operating voltages enable longer transmission lines but better insulation materials with a much lower conductivity than today´s crosslinked polyethylene (PE) are required to reach the goal of 1 MV by 2030. Nanocomposites consisting of small fractions of metal oxide nanoparticles in PE are promising insulation materials, showing ca. 100 times lower conductivity. The reasons for the better insulating properties are however not fully understood. The properties of PE and inorganic nanoparticles were studied in this project to evaluate the influence of different material parameters on the conductivity of the cable insulation material. For pristine PE, the polymer morphology and oxidation were found to have a significant impact on the conductivity. For PE nanocomposites, the particle/polymer interface was shown to adsorb polar molecules, which are present in PE cable insulation. A suggested hypothesis is that the adsorption on particle surfaces results in cleaning of the bulk polymer from impurities, which in turn contributes to decreased nanocomposite conductivity. Since the particle interface is believed to be decisive for the nanocomposite properties, the role of particle terminations was investigated in detail. Oxygen dominated particle terminations resulted in 2 times higher composite conductivity than with zinc dominated surfaces, while fully oxygen covered surfaces showed 10 times higher conductivity. Composite systems with micro-sized particles allowed for evaluating parameters independently, which is not possible for nanocomposites. Terminations of ‘PE-like’ hydrocarbon chains lowered the conductivity and these trends could also be transferred to similar zinc oxide nanocomposite systems., Distribution av elektrisk energi över långa avstånd genom att använda högspänd likström (HVDC) blir allt viktigare för att ställa om till en förnyelsebar energiproduktion (t.ex. solkraft, vindkraft och vattenkraft). Med ökad driftspänning kan längre kabelsystem användas på grund av minskade förluster, men detta ställer högre krav på isoleringsmaterialet. Nya koncept med bättre isolerande egenskaper (t.ex. lägre konduktivitet) än dagens tvärbundna polyeten (PE) måste utvecklas för att kunna uppnå målet med en driftspänning på 1 MV till 2030. Kompositer bestående av nanopartiklar i PE är ett lovande alternativ som är ca. 100 gånger mer isolerande än PE men kunskapen om varför kompositer uppvisar bättre isolerande egenskaper är inte komplett. Egenskaper hos PE och inorganiska nanopartiklar studeras i detta projekt för att utvärdera vilken betydelse olika parametrar har för DC konduktiviteten. För ren PE så påverkade polymerens morfologi och oxidation konduktiviteten signifikant. För nanokompositer är gränsytan mellan partikel och polymer viktig för kompositens egenskaper och det visades att polära molekyler som finns i kabelisolering av PE adsorberades på partikelytorna. Det föreslogs att adsorptionen bidrar till en renare polymer i kompositerna, vilket i sin tur minskar konduktiviteten. Termineringar på zinkoxidpartiklar undersöktes i detalj och partiklar med en majoritet av syre på ytan ökade kompositens konduktivitet 2 gånger jämfört med dominerande termineringar av zink. Ytor helt täckta av syre ökade konduktiviteten 10 gånger. Påverkan av funktionaliteten på partikelytan kunde studeras oberoende av andra parametrar genom att använda större mikropartiklar, vilket inte är möjligt för nanopartiklar. Slutsatsen att partikelytor med kolväten som liknar PE sänkte konduktiviteten jämfört med syredominerande ytor kunde även bekräftas för kompositer med nanopartiklar., QC 2020-05-25

A new method for stirring under high pressure conditions has been developed and tested. The key component is a Teflon cell assembly equipped with magnetic stirring function, which is capable to operate across a wide pressure range, up to at least 2 GPa, in a large volume press. The setup enables adjustable stirrer rotation rate and detection of stirring in a sample,e.g.to observe liquid-solid phase transitions at high pressure. The viscosity limit of stirring is ca. 500 times that of water at room temperature (i.e.similar to 500 mPas). Moreover, we show that zinc oxide nanoparticles hydrothermally synthesized at 0.5 GPa and 100 degrees C under stirring conditions show an order of magnitude smaller size (100 nm) compared to those synthesized under non-stirring conditions (1 mu m). The wide pressure range for stirring of viscous media opens interesting possibilities to produce novel materials via hydrothermal synthesis and chemical reactions.

A new method for stirring under high pressure conditions has been developed and tested. The key component is a Teflon cell assembly equipped with magnetic stirring function, which is capable to operate across a wide pressure range, up to at least 2 GPa, in a large volume press. The setup enables adjustable stirrer rotation rate and detection of stirring in a sample,e.g.to observe liquid-solid phase transitions at high pressure. The viscosity limit of stirring is ca. 500 times that of water at room temperature (i.e.similar to 500 mPas). Moreover, we show that zinc oxide nanoparticles hydrothermally synthesized at 0.5 GPa and 100 degrees C under stirring conditions show an order of magnitude smaller size (100 nm) compared to those synthesized under non-stirring conditions (1 mu m). The wide pressure range for stirring of viscous media opens interesting possibilities to produce novel materials via hydrothermal synthesis and chemical reactions.

A new method for stirring under high pressure conditions has been developed and tested. The key component is a Teflon cell assembly equipped with magnetic stirring function, which is capable to operate across a wide pressure range, up to at least 2 GPa, in a large volume press. The setup enables adjustable stirrer rotation rate and detection of stirring in a sample,e.g.to observe liquid-solid phase transitions at high pressure. The viscosity limit of stirring is ca. 500 times that of water at room temperature (i.e.similar to 500 mPas). Moreover, we show that zinc oxide nanoparticles hydrothermally synthesized at 0.5 GPa and 100 degrees C under stirring conditions show an order of magnitude smaller size (100 nm) compared to those synthesized under non-stirring conditions (1 mu m). The wide pressure range for stirring of viscous media opens interesting possibilities to produce novel materials via hydrothermal synthesis and chemical reactions.

We investigated the toxicity of Iron oxide and Zinc oxide engineered nanoparticles (ENPs) on Paracentrotus lividus sea urchin embryos and three species of microalgae. Morphological responses, internalization, and potential impacts of Fe2O3 and ZnO ENPs on physiology and metabolism were assessed. Both types of ENPs affected P. lividus larval development, but ZnO ENPs had a much stronger effect. While growth of the alga Micromonas commoda was severely impaired by both ENPs, Ostreococcus tauri or Nannochloris sp. were unaffected. Transmission electron microscopy showed the internalization of ENPs in sea urchin embryonic cells while only nanoparticle interaction with external membranes was evidenced in microalgae, suggesting that marine organisms react in diverse ways to ENPs. Transcriptome-wide analysis in P. lividus and M. commoda showed that many different physiological pathways were affected, some of which were common to both species, giving insights about the mechanisms underpinning toxic responses

The rational control of the electrochemical properties of polyoxovanadate-alkoxide clusters is dependent on understanding the influence of various synthetic modifications on the overall redox processes of these systems. In this work, the electronic consequences of ligand substitution at the heteroion in a heterometal-functionalized cluster was examined. The redox properties of [V5 O6 (OCH3 )12 FeCl] (1-[V5 FeCl]) and [V5 O6 (OCH3 )12 Fe]X (2-[V5 Fe]X; X=ClO4 , OTf) were compared in order to assess the effects of changing the coordination environment around the iron center on the electrochemical properties of the cluster. Coordination of a chloride anion to iron leads to an anodic shift in redox events. Theoretical modelling of the electronic structure of these heterometal-functionalized clusters reveals that differences in the redox profiles of 1-[V5 FeCl] and 2-[V5 Fe]X arise from changes in the number of ligands surrounding the iron center (e.g., 6-coordinate vs. 5-coordinate). Specifically, binding of the chloride to the sixth coordination site appears to change the orbital interaction between the iron and the delocalized electronic structure of the mixed-valent polyoxovanadate core. Tuning the heterometal coordination environment can therefore be used to modulate the redox properties of the whole cluster.

This work reports a method to reduce the process thermal budget in metal oxide (MO) thin-film transistors (TFTs). Using the thermal curing of a fluorinated polyimide planarization (PLN) layer as an efficient device activation process, this method eliminates the need for additional annealing steps before the existing PLN process in the fabrication. Bottom-gated TFTs with indium tin oxide (ITO)-stabilized ZnO channels were fabricated by this method and exhibited improved electrical characteristics over control devices made with a higher thermal budget. A steep subthreshold swing of 82.8 mV/decade and a high on-off ratio of 1.3×1010 were achieved. This improvement can be attributed to the fluorine diffusion from the PLN layer to the MO channels during the curing step. This method is useful for the cost-effective production of active-matrix flat-panel display (AM-FPD) panels and the implementation of MO TFTs on flexible substrates. IEEE

A new method for stirring under high pressure conditions has been developed and tested. The key component is a Teflon cell assembly equipped with magnetic stirring function, which is capable to operate across a wide pressure range, up to at least 2 GPa, in a large volume press. The setup enables adjustable stirrer rotation rate and detection of stirring in a sample,e.g.to observe liquid-solid phase transitions at high pressure. The viscosity limit of stirring is ca. 500 times that of water at room temperature (i.e.similar to 500 mPas). Moreover, we show that zinc oxide nanoparticles hydrothermally synthesized at 0.5 GPa and 100 degrees C under stirring conditions show an order of magnitude smaller size (100 nm) compared to those synthesized under non-stirring conditions (1 mu m). The wide pressure range for stirring of viscous media opens interesting possibilities to produce novel materials via hydrothermal synthesis and chemical reactions.