Дисертації з теми "COPPER OXIDE NANOPARTICLE"

Philosophiae Doctor - PhD (Chemistry)
Supercapacitors, also known as ultracapacitors or electrochemical capacitors, are considered one of the most important subjects concerning electricity or energy storage which has proven to be problematic for South Africa. In this work, graphene oxide (GO) was supported with platinum, silver and copper nanoparticles anchored with dodecylbenzenesulphonic acid (DBSA) doped polyaniline (PANI) to form nanocomposites. Their properties were investigated with different characterization techniques. The high resolution transmission electron microscopy (HRTEM) revealed GO's nanosheets to be light, flat, transparent and appeared to be larger than 1.5 ?m in thickness. This was also confirmed by high resolution scanning electron microscopy (HRSEM) with smooth surfaces and wrinkled edges observed with the energy dispersive X-ray analysis (EDX) confirming the presence of the functional groups such as carbon and oxygen. The HRTEM analysis of decorated GO with platinum, silver and copper nanoparticles (NPs) revealed small and uniformly dispersed NPs on the surface of GO with mean particle sizes of 2.3 ± 0.2 nm, 2.6 ± 0.3 nm and 3.5 ± 0.5 nm respectively and the surface of GO showed increasing roughness as observed in HRSEM micrographs. The X-ray fluorescence microscopy (XRF) and EDX confirmed the presence of the nanoparticles on the surface of GO as platinum, silver and copper which appeared in abundance in each spectra. Anchoring the GO with DBSA doped PANI revealed that single GO sheets were embedded into the polymer latex, which caused the DBSA-PANI particles to become adsorbed on their surfaces. This process then appeared as dark regions in the HRTEM images. Morphological studies by HRSEM also supported that single GO sheets were embedded into the polymer latex as composite formation appeared aggregated and as bounded particles with smooth and toothed edges.

Les travaux dans cette thèse ont pour objectif la synthèse de catalyseurs (nanoparticules de cuivre) de taille contrôlée pour la synthèse de nanofils de silicium dans des conditions compatibles CMOS, c'est-à-dire en évitant l'utilisation de l'or comme catalyseur et pour des croissances basse température (<450°C). Les résultats obtenus ont permis de montrer que les techniques de chimie de surface classiquement utilisées pour la préparation de catalyseurs sur des supports 3D (silice, nitrure de titane…) sont directement applicables et transférables sur des supports 2D (wafer de silicium recouvert de films fins de SiO2, SiOx et TiN). Nous avons par exemple pu préparer des nanoparticules de cuivre de taille contrôlée (de 3 nm à 40 nm de diamètre moyen suivant les conditions expérimentales et supports). De plus, les mécanismes de formation des nanoparticules en fonction des propriétés de surface des matériaux étudiés ont été démontrés en combinant diverses techniques d'analyses de surface. La croissance de nanofils de silicium à partir de ces catalyseurs sur substrats 2D a également été réalisée avec succès dans des procédés à basse température. Il a notamment été montré l'existence d'un diamètre minimum critique à partir de laquelle la croissance basse température était possible
The work presented in this PhD thesis aimed at the preparation of copper nanoparticles of controllable size and their utilization as catalysts for the growth of silicon nanowires in a process compatible with standard CMOS technology and at low temperature (< 450°C). The growth of silicon nanowires by Chemical Vapor Deposition (CVD) via the catalytic decomposition of a silicon precursor on metallic nanoparticles at low temperature (Vapor Solid-Solid process) was demonstrated to be possible from an oxidized Cu thin film. However, this process does not allow the control over nanowires diameter, which is controlled by the diameter of the nanoparticle of catalyst. In this PhD is presented a fully bottom-up approach to prepare copper nanoparticles of controllable size directly on a surface without the help of external stabilizer by mean of surface organometallic chemistry. First, the preparation of copper nanoparticles is demonstrated on 3D substrates (silica and titanium nitride nanoparticles), along with the fine comprehension of the formation mechanism of the nanoparticles as a function of the surface properties. Then, this methodology is transferred to planar (2D) substrates typically used in microelectronics (silicon wafers). Surface structure is demonstrated to direct the Cu nanoparticles diameter between 3 to 40 nm. The similarities between the 2D and 3D substrates are discussed. Finally, the activity of the Copper nanoparticles in the growth of Silicon nanowire is presented and it is demonstrated that in our conditions a critical diameter may exist above which the growth occurs

The dye sensitized solar cell (DSSC) is a promising low-cost technology alternative to conventional solar cell in certain applications. A DSSC is a photo-electrochemical photovoltaic device, mainly composed of a working electrode, a dye sensitized semiconductor layer, an electrolyte and a counter electrode. Sunlight excites the dye, producing electrons and holes that can be transported by the semiconductor and electrolyte to the external circuit, converting the sunlight into an electrical current. A material that could be useful for DSSCs is the nanoscale cupric oxide, which can act as a p-type semiconductor and has interesting properties such as low thermal emittance and relatively good electrical properties. The goal of this project was to synthesize and characterize CuO nanoparticles using three different methods and look into each products potential use and efficiency in DSSCs. The particles were synthesized using two different solution based chemical precipitation methods and a flame spray pyrolysis method, yielding nanostructures with different compositions, structures and sizes ranging from ~20 to 1000 nm. The nanoparticle powder synthesized by the flame spray pyrolysis route was tested as semiconductor layer in the working electrode of the DSSC. Current-voltage measurements presented low solar conversion efficiencies with a reversed current, meaning that the cupric oxide cells did not work in a desirable way. Further studies of the cupric oxide synthesis and its suitability in DSSCs are needed to increases the future possibilities for gaining well working p-type DSSCs with higher efficiencies.

Copper oxide nanoparticles (NPs) are used in an expanding range of industries including a potential for agricultural applications as a fungicide. Accidental spills or misapplication of CuO NPs may lead to soil contamination. Plant roots exude a wide range of organic chemicals for bioprotection and to enhance bioavailability of nutrients. Many of these chemicals are metal chelators that may increase the solubility of CuO NPs, thus enhancing the impact of these NPs on plants. This work was directed towards understanding which plant exudates force increased solubility of CuO NPs and to determine if the level of NP in the growth matrix drives a feedback effect, regarding composition and quantity of exudates. Wheat seedlings (Triticum aestivum cv Deloris) were grown in a sand matrix for 10 days after 3 days of germination. The sand was amended with sublethal doses of CuO NPs from 0 to 300 mg Cu/kg dry sand. Sand was selected as the solid growth matrix as a proxy for soil in terms of plant root morphology, mechanical impedance and water stress, while providing a low background of dissolved organic carbon for the isolation of root exudates. After plant growth, the pore water was collected from the sand by vacuum filtration and analyzed. By coupling analytic techniques including Triple Quad Mass Spectroscopy and ion chromatography with geochemical modeling, we have identified citrate and the phytosiderophore, deoxymugineic acid (DMA) as chelators that drove the majority of dissolution of CuO NPs, especially DMA at higher CuO NP doses. Altered biogeochemistry within the rhizosphere was correlated with increased plant uptake of Cu and bio-response via exudate type, quantity and metal uptake. Exposure of wheat to CuO NPs lead to dose-dependent reduction in Fe, Ca, Mg, Mn and K in roots and shoots. This work is relevant to growth of commercially important crop wheat in the presence of CuO NPs as a fertilizer, fungicide or a pollutant.

Optical properties of copper oxide nanoparticles in a silica matrix thin film have been investigated. Films were prepared on Si substrates from a sol-gel by spin coating. Four samples with different thicknesses, from 14,5-109 nm, were fabricated. Optical properties were measured with Variable Angle Spectroscopic Ellipsometry. The aim of the project was to gain further understanding of these films that are interesting in applications for solar absorbers as solar selective coatings. Ellipsometricangles Ψ and Δ were measured in the wavelength range from 250-1700 nm. A dispersion model was developed and fitted to experimental data with acceptable results.

The persistence of biofilms in hospital settings are associated with Healthcare Associated Infections (HCAI), causing increased morbidity, mortality and healthcare costs. The resistance of biofilms against commonly used hospital disinfectants has been well reported. Metal and metal oxide nanoparticles (NP) such as silver (Ag), copper (Cu), zinc oxide (ZnO) and copper oxide (CuO) exhibit antimicrobial properties against various pathogens. Methods: Biofilm formation of Pseudomonas aeruginosa and Staphylococcus aureus in a Centre for Disease Control (CDC) biofilm reactor and a 96 well plate was compared. A three stage approach including Minimum Biofilm Reduction Concentration (MBRC), R2 values and log(10) reductions was used to assess the efficacy of Ag and ZnO NPs both alone and in combination against P. aeruginosa and S. aureus biofilms. Atomic Absorption Spectroscopy (AAS), Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM) was used to further assess the antimicrobial ability of the metal and metal oxide NPs. The prevention of P. aeruginosa and S. aureus adherence on Ag and ZnO thin film coating on silicon (Si) surfaces was also investigated, as well as icaC, ebpS and fnbB gene expression in S. aureus biofilms. Results: The CDC biofilm reactor demonstrated to be the most effective method for P. aeruginosa and S. aureus biofilm production in comparison to 96 well plates, with lower standard errors of the mean (SE) and higher replicability. Individual MBRC of ZnO and Ag NPs in suspension were 256 and 50 µg/ml for P. aeruginosa and 16 and 50 µg/ml for S. aureus respectively. The concentrations in combination were reduced by at least a half, with concentrations of 32/25 µg/ml of ZnO/Ag NPs in suspension resulting in a significant (p ≤0.05) reduction of 3.77 log(10) against P. aeruginosa biofilms and 8/12 µg/ml of ZnO/Ag NPs in suspension resulted in a 3.91 log(10) (p ≤0.05) against S. aureus biofilms. Both combinations showed an additive effect. Time point analysis confirmed that a 24 hour treatment is vital for any significant (p ≤0.05) antimicrobial activity. AAS data suggested that the Ag+ ions quenched Zn2+ ions, therefore the antimicrobial efficacy of the combination is mainly due to Ag+ ions. Damage of the biofilms from Ag and ZnO NPs was observed in the SEM imaging and energy dispersive X-ray (EDX) analysis confirmed the adherence of Zn and Ag within the biofilms. CLSM imaging showed dead (red) cells of P. aeruginosa and S. aureus biofilms throughout the depth of the biofilm. P. aeruginosa formation was reduced by 1.41 log(10) and 1.43 log(10) on Ag and ZnO thin film coatings respectively. For S. aureus, a reduction of 1.82 log(10) and 1.65 log(10) was obtained for Ag and ZnO coating respectively. Only low levels of ribonucleic acid (RNA) were achieved so no further gene analysis could occur. Conclusion: Reductions of ≥3 log(10) were observed for P. aeruginosa and S. aureus biofilm treatment with ZnO/Ag NP suspensions. It can be concluded that the ZnO/Ag NP suspensions had greater antimicrobial activity than Ag and ZnO coated surfaces owing to large concentrations of Ag+ and Zn2+ ions acting upon the biofilms. The slower release of ions from coated surfaces suggest an inadequate concentration of ions in the media, which are therefore unable to prevent biofilm formation as rapidly as NP suspensions, however provide a sustained release of ions over time. The results from this investigation propose that Ag and ZnO NPs in suspension could be a potential alternative to disinfectants for use in nosocomial environments against P. aeruginosa and S. aureus biofilms.

The goal of this project was to study the behavior of copper oxide nanoparticles in soil environments. Copper oxide nanoparticles have antimicrobial properties and may also be used in agricultural settings to provide a source of copper for plant health, but accidental or misapplication of these nanoparticles to soil may be damaging to the plant and its associated bacteria. Dissolved soil organic matter that is present in soil pore waters dissolved nanoparticles, but did not dissolve the expected amounts from a geochemical model because the geochemical model did not take into account surface chemistry or coating of the nanoparticles by dissolved organic matter. Wheat grown in soil pore water increased the solubility of the nanoparticles. The nanoparticles and dissolved copper were harmful to wheat, but dissolved soil organic matter remediated a portion of the damage. These studies were conducted with Utah soils and wheat, a highly valuable Utah crop. These results suggest that contamination of soils by copper oxide nanoparticles will be partially mitigated by the organic matter content of the soil. Producers of fertilizers and fungicides may use various forms of organic matter to deliver products that are targeted to specific plants or pathogens and avoid damage to non-target organisms.

In this paper the composites Ag / SiO2 with regularly distributed in bulk matrix silver and copper oxide nanoparticles were synthesized. Herewith, copper ions was introduced into porous support at the stage of sol-gel synthesis. Sample Ag / CuO / SiO2 was tested by the catalytic reaction of CO oxidation and com-pared with Ag / SiO2. It was revealed that sample with introduced copper show lower activity .This fact can be explained by formation of silver cuprate during preparation of composite Ag / CuO / SiO2. Treatment by reaction mixture (CO and O2) led to release of silver in ionic, clusters and metal states that increased cata-lytic activity of the composite. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35611

Dans les cellules photovoltaïques organiques, le matériau utilisé pour le transport de trous entre la couche active et l'électrode, est généralement un polymère dopé, dont la stabilité peut être problématique. L'objectif de cette thèse a été de développer des matériaux inorganiques, a priori plus stables, pour remplacer les couches de polymères de transport de trous, tout en restant compatible avec les méthodes de dépôts par voie liquide. L'utilisation de nanoparticules dispersées en solution a été choisie car cela permet le dépôt à basse température, sans nécessité de conversion vers une couche fonctionnelle, contrairement aux voies sol-gel. Le premier objectif de ce travail a donc été l'obtention de nanoparticules d'oxyde de tungstène, hydraté ou non, et de thiocyanate de cuivre. Une synthèse de chauffage assisté par micro-ondes a été utilisée pour l'oxyde de tungstène, permettant d'obtenir des nanoparticules de 30 nm et monodisperses. Pour le thiocyanate de cuivre, il a été choisi de travailler par broyage. Les paramètres du broyage ont été optimisés pour obtenir des particules avec la plus faible distribution en taille possible. Le dépôt de ces dispersions de nanoparticules a permis l'obtention de couches minces et la caractérisation de leurs propriétés optoélectroniques, et notamment du travail de sortie, qui s'est révélé adapté pour une utilisation en dispositif. Des cellules solaires organiques de structures standard et inverse incorporant ces matériaux ont ensuite été réalisées. De bonnes performances ont été obtenues avec une couche active à base de P3HT, notamment en structure inverse où la possibilité d'utiliser le thiocyanate de cuivre a été démontrée pour la première fois. Le suivi des performances sous éclairement et atmosphère contrôlée a également été effectué et a montré un vieillissement rapide pour ces cellules comparées aux cellules de référence à couche de transport de trous polymère
In organic solar cells, a doped polymer is the most used material for hole transport between the active layer and the electrode, but his stability can be an important issue. The goal of this PhD thesis was to develop inorganic materials, expected to be more stable, in order to replace polymer based hole transporting layers. Another requirement was to keep the compatibility with solution-based deposition methods. The target was to develop nanoparticle dispersions, deposited at low temperature and giving directly a functional layer, without the need of further treatments which are usually required via sol-gel processes. A first objective of the present work was thus the elaboration of nanoparticles of tungsten oxide, hydrated or non-hydrated, and copper thiocyanate. A microwave-assisted heating synthesis has been used for tungsten oxide, leading to mono-dispersed particles around 30 nm. Concerning copper thiocyanate, a ball milling technique has been chosen. The process parameters have been optimized to obtain nanoparticles to narrow the size distribution as much as possible. The deposition of the nanoparticles has allowed the formation of thin layers and the characterization of their optoelectronic properties, such as work function, which was shown to be a relevant parameter for a use in devices. Organic solar cells with standard or inverted structures have been fabricated using these materials as a hole transporting layer. Good photovoltaic performances have been obtained, especially in the inverted structure, in which the possibility to use copper thiocyanate has been demonstrated for the first time. Ageing experiments under light in a controlled atmosphere have also been carried out and have shown a rapid drop in performances for these cells compared to cells incorporating polymer based hole transport layers

The atomic layer deposition (ALD) of copper oxide films from [(ⁿBu₃P)₂Cu(acac)] and wet oxygen on SiO₂ and TaN has been studied in detail by spectroscopic ellipsometry and atomic force microscopy. The results suggest island growth on SiO₂, along with a strong variation of the optical properties of the films in the early stages of the growth and signs of quantum confinement, typical for nanocrystals. In addition, differences both in growth behavior and film properties appear on dry and wet thermal SiO₂. Electron diffraction together with transmission electron microscopy shows that nanocrystalline Cu₂O with crystallites < 5 nm is formed, while upon prolonged electron irradiation the films decompose and metallic copper crystallites of approximately 10 nm precipitate. On TaN, the films grow in a linear, layer-by-layer manner, reproducing the initial substrate roughness. Saturated growth obtained at 120°C on TaN as well as dry and wet SiO₂ indicates well-established ALD growth regimes.
© 2009 The Electrochemical Society. All rights reserved.

Dans cette étude, la nucléation, la croissance, la morphologie et la réactivité de nanoparticules Au, Cu et AuCu sont examinées sur support rutile TiO2 (110) stoechiométrique, réduit et hydraté. En premier lieu, la nucléation a été modélisée via l’adsorption et la diffusion d’atomes Au et Cu, à l’aide de calculs de type théorie de la fonctionnelle de la densité (DFT), et de diagrammes d’énergie libre en condition réaliste.Les résultats DFT+U ont montré le rôle promoteur des espèces hydroxyles en surface sur la nucléation, en accord avec les mesures expérimentales de microscopie STM. Ensuite, les propriétés thermodynamiques de croissance et de coalescence de clusters Au et Cu (de 1 à 38 atomes) ont été étudiées par une approche systématique qui a déterminé précisément la stabilité relative d’un grand nombre de structures, tout en soulignant la différence de compétition nucléation/croissance entre les deux métaux. Pour des tailles de particules comprises entre 38 et 201 atomes, et des morphologies variées, la stabilité absolue d’agrégats purs Au et Cu et de nanoalliages AuCu a été évaluée à l’aide de calculs d’énergie de surface. Cette approche a révélé l’existence de relations linéaires entre composition chimique et stabilité. Enfin, la réactivité de nanoparticules Au, Cu et AuCu a été examinée suivant deux aspects : le dépôt de clusters de 38 atomes sur support rutile stoechiométrique, et l’adsorption du monoxyde de carbone à l’interface entre le métal et le support.Cette adsorption est une étape clé pour la réaction d’oxydation du CO ; un procédé important en catalyse hétérogène
In this study, the nucleation, growth, morphology and reactivity of Au, Cu and AuCu nanoparticles have been examined on rutile TiO2 (110) stoiciometric, reduced and hydrated supports. First, the nucleation has been modeled via the adsorption and diffusion of Au and Cu atoms, thanks to density functional theory (DFT) calculations, and free energy diagrams in realistic conditions. DFT+U results have shown the promotor role of surface hydroxyl species on the nucleation, in agreement with STM experimental measurements.Then, the growth and coalescence thermodynamic properties for Au and Cu clusters (from 1 to 38 atoms) have been investigated with a systematic approach which has determinated precisely the relative stability for a large number of structures, and has underlined the difference for the competition between nucleation and growth between the two metals. For particles in the range 38-201 atoms and varied morphologies, the absolute stability of Au and Cu aggregates and AuCu nanoalloys has been evaluated through surface energy calculations. This approach has revealed the existence of linear relations between the chemical composition and the stability.Finally, the reactivity of Au, Cu and AuCu nanoparticles has been examined following two aspects : the deposition of 38 atoms clustered on the stoichiometric rutile support, and the adsorption of carbon monoxide at the interface between the metal and the support. This adsorption is a key step for the CO oxidation reaction ; an important process in heterogeneous catalysis

A significant effort has been made recently to develop second-generation HTSC tapes. In these tapes, ReBaCuO (rare-earth barium copper oxide - YBCO) thin films are produced on metallic substrates, such as textured Ni, NiW alloys and stainless steel. To prevent the interdiffusion of elements between metal substrate and superconducting material, and to match the YBCO lattice parameters with the substrate texture, different buffer layers were deposited on the substrate. In commercially available HTSC tapes, several buffer layers are typically used to obtain high-quality YBCO superconductor coatings (i.e. appropriate texture, defect-free and with a high critical current density, Jc,). Many existing HTS tape technologies use a variety of buffer layer architecture, which include YSZ, MgO, Y2O3 and CeO2 nm-thick layers and their combinations.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
Full Text

Dans ce travail, après l’état de l’art et la présentation de méthodes de synthèse et d’analyse, nous présentons des résultats sur la croissance sélective de Cu2O et Cu métallique par dépôt par couche atomique (ALD) sur ZnO, ZnO dopé à l’Al (AZO) et α-Al2O3. Nous mettons en évidence la possibilité de déposer de façon sélective Cu métallique ou Cu2O, en contrôlant la température de dépôt et la conductivité ou la densité des défauts ponctuels au sein du substrat. Un procédé sélectif local de dépôt par couche atomique (AS-ALD) a été mis en évidence sur une bicouche à motifs composée de zones de ZnO de faible conductivité et de régions d’AZO de forte conductivité. De plus, l'AS-ALD permet la fabrication de nano-jonctions à base de Cu2O/ZnO /AZO/Cu, dont le comportement de jonction p-n a été confirmé par microscopie à force atomique à pointe conductrice (C-AFM). Les mécanismes liés à la croissance sélective locale sont également discutés. Dans la seconde partie de cette thèse, des nanoparticules de Cu (NP) ont été déposées par ALD sur des couches minces de ZnO. Les NP de Cu présentent une résonance plasmon de surface localisée caractérisée par ellipsométrie. La position de la bande de résonance plasmon est ajustable entre les régions visible et infrarouge du spectre électromagnétique en gérant la taille des particules et leur espacement par l’intermédiaire du temps de dépôt. Le système Cu NP/ZnO montre une photo-réponse dans le visible grâce à la génération d'électrons chauds à la surface des NP de Cu et l'injection dans la bande de conduction de ZnO. Finalement, des hétérojonctions Cu2O/ZnO semi-transparentes ont été fabriquées par ALD et pulvérisation cathodique. Les hétérojonctions présentent une photo-réponse autoalimentée sous éclairement, des temps de réponse rapides et une transparence élevée dans le visible, ce qui est prometteur pour des applications dans les domaines de l’électronique transparente, la photo-détection et le photovoltaïque
In this work we present the results on the selective growth of Cu2O and metallic Cu by atomic layer deposition (ALD) on ZnO, Al-doped ZnO (AZO) and α-Al2O3 substrates. It was possible to tune the deposited material (Cu or Cu2O) by controlling the deposition temperature, and the substrate conductivity/density of donor defects. An area-selective atomic layer deposition (AS-ALD) process was demonstrated on a patterned bi-layer structure composed of low-conductive ZnO, and highly-conductive AZO regions. Furthermore, the AS-ALD allows the fabrication of Cu2O/ZnO/AZO/Cu-back-electrode nanojunctions, as confirmed by conductive atomic force microscopy (C-AFM). The mechanism behind the temperature and spatial selectivities is discussed. In a second part of this thesis, Cu nanoparticles (NP) were deposited by ALD on ZnO thin films. The Cu NP exhibit a localized surface plasmon resonance, tunable from the visible to the near-infrared regions, as confirmed by spectroscopic ellipsometry. An enhanced visible photo-response was observed in the Cu NP/ZnO device thanks to the hot-electron generation at the surface of the plasmonic Cu NP and transfer into the conduction band of ZnO. Finally, semi-transparent Cu2O/ZnO heterojunctions were fabricated by ALD and reactive magnetron sputtering. The heterojunctions present a stable self-powered photo-response under 1 Sun illumination, fast response times and high transparency in the visible region, which is promising for all-oxide transparent electronics, photodetection and photovoltaics

This research is directed towards understanding the mechanisms associated with the manufacture of solid microspheres less than 100 [micrometers], from liquid droplets with nanosuspensions in a microfluidic T-junction, which are heated downstream of the channel. Preliminary material characterization tests on colloidal suspensions of alumina and copper oxide demonstrate promising temperature dependent viscosity results indicating solidification in the temperature range of 40°C-50°C. The solidification mechanism is referred to as Temperature Induced Forming and is described by polymeric bridges formed between nanoparticles in suspension at elevated temperatures, resulting in a solid structure. The polymer network results from the ionization of alumina at elevated temperatures whereby polymeric binders adhere to newly formed charged sites on the alumina particle. This study aims to investigate the aspects of manufacturing microstructures in microfluidic Tjunctions, droplet morphology, size and frequency of production. Preliminary low solid concentration experiments (1%-10% volume concentration of alumina in H2O) have indicated solidification and a regression in droplet diameter when heated near the saturation temperature of the water used to disperse the particles. The microstructures from this solidification process are uniform and are estimated to be 30 [micrometers] in size.
B.S.M.E.
Bachelors
Mechanical, Material and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering

The recovery of different types of metals from wastes has had a spreading interest in the last years. One reason is that wastes, and in particular e-waste, contain metals which are considered strategic. In fact, the availability of these metals is limited and decreases, as natural resources are limited, and their prices fluctuate according to the markets and the management policy of the resource country. Actually, strategic metals are generally defined as those metals that are required for the national defense of a country, but are threatened by supply disruptions due to limited domestic production. However, the definition of strategic metals can be also including those metals that are important not only for national defense, but also for industries that play an important role in the economic development of a country such as energy, aerospace, telecommunication, computer or mobile technology. Thus, it has become quite interesting and urgent to find a strategic way to recover these metals from the wastes. In this work, the recovery of resources from different wastes was studied. In particular, after the introduction and the description of the experimental systems used in this research, the recovery of gold, together with other metals (silver, copper and tin), from the printed circuit boards (PCBs) of end of life (EOL) mobile phones is discussed in Chapter 3. Actually, both the most dangerous and the most precious metals could be founded in PCBs. In particular, it was studied a process which consists in an acid leaching process followed by the gold complexation with thiourea or thiosulphate, two substances that represent an alternative to the more toxic cyanides typically used for the selective gold dissolution. Furthermore, the effect of the ultrasound during the leaching was examined, in order to improve the recovery yield. In fact, in the latest years, ultrasound has been investigated to assist hydrometallurgical metals extraction from ores and minerals but their industrial application is until now limited, although the advantages derived from their application are: a greater metal release in shorter time, lower consumption of reagents and lower process temperature. Therefore, the use of ultrasound could represent an advantage because it increases the recovery of precious metals from the waste. Subsequently, a study was conducted to evaluate a method to recovery silver from the end-of-life solar cells and, more generally, to design a simple and cheap process for the full recovery of the materials constituent the photovoltaic panels. In fact, different methods both hydrometallurgical and pyrometallurgical were tested and the best results were obtained using a combination of a heating treatment and three hydrometallurgical ones. The process parameters were optimized, both for heating and chemical treatments. The results of this study are presented in Chapter 4. Moreover, because the idea seems economically valuable, the process in lab scale was also improve at TRL 5 and the obtained results were used to apply successfully for European funding. In fact, “ReSiELP” project was approved, with the aim to improve the TRL of the technology from 5 to 7. Successively, in Chapter 5 is described the study of recovering Tantalum from EOL capacitors and Neodymium from permanent magnets. In order to separate tantalum from silica, a new treatment with hydrofluoric acid was investigated and tested, whereas the process known in literature for neodymium recovery, was modified introducing a treatment with ammonia which increase the purity of recovered neodymium and sodium double salt. After these studies about metals extraction from e-wastes, a method to increase the added value of recovered material was investigated. In fact, besides the intrinsic value of these metals, a further value could be achieved by recovering these metals in form of nanoparticles, which exhibit very interesting and promising properties in comparison with the corresponding bulk materials. Size-dependent properties include, but are not limited to, the following: optical, magnetic, catalytic, thermodynamic, electrochemical properties and electrical transport. Moreover, nanomaterials may provide solutions to technological and environmental challenges in the areas of solar energy conversion, catalysis, medicine, and water treatment. Different nanoparticles were produced using as raw material the solutions in which electronic scraps were previously leached. In particular, nanoparticles of tin dioxide, silver, copper, cuprous oxide, gold and iron were synthetized and characterized and the results of the study are presented in Chapter 6. All the nanoparticles were synthesized using hydrometallurgical processes and the reagents used were environmentally friendly (like ascorbic acid or glucose syrup) as well as the technologies (ultrasound) used to produce them and to improve the yields in metals extraction from the e-waste. The use of ultrasound in nanoparticles production allows to reduce the sizes of the products thanks to the cavitation effect which produces locally extreme conditions during the nanoparticles nucleation and growth processes. Different processes were developed to produce the six different type of nanoparticles. The materials obtained were analysed by inductive coupled plasma, scanning and transmission electron microscopy, x-ray diffraction, laser diffraction particle size analyser and UV-spectroscopy. The results showed that the developed methods allow to recover the metals with high yield and to produce high purity nanoparticles of tin dioxide, silver, copper, cuprous oxide, gold and iron with sizes between 2 and 200 nm. Finally, some interesting and innovative application for the recovered metals, in particular silver and copper, were also studied and the results are presented in Chapter 7 of this thesis work. The silver and copper powder were introduced into Plasma Electrolytic Oxidation coating. Plasma electrolytic oxidation (PEO), also called ‘Microarc Oxidation’ (MAO) is relatively new surface modification technique that shows an increasing interest in the production of oxide ceramic coatings on light alloys such as aluminium, titanium or magnesium. PEO coatings can enhance the corrosion and wear resistance properties of these metals, or can confers to the light alloys various other functional properties including anti-friction, thermal protection, optical and dielectric features. Furthermore, PEO can be used as a pre-treatment to provide load support for top layers. PEO is a process derived from conventional anodizing which shows many advantages such as higher corrosion and wear resistance performances of the coatings, more environmental friendly electrolytes and the possibility to include into the coatings particles coming from the electrolyte. PEO of metals is a complex process that combines oxide film formation, dissolution and dielectric breakdown: the sample, as anode, is immersed in an electrolyte and it works with high voltages and current densities inside a tank which constitute the cathode of the electrolytic cell. Due to the high voltage that needs to overcome the dielectric breakdown potential of the oxide layer, the formation of a persistent anodic micro-discharges on the surface during the PEO treatment is observed. These short-lived micro-discharges are the key of the process; they move randomly over the surface and produce the growth of an oxide ceramic coating and they also allow to incorporate compounds from the electrolyte into the coating. In the studies presented in this thesis silver and copper powder were introduced into PEO coating by direct addition into the electrolyte to improve respectively the antimicrobial/antifungal and the antifouling properties of the sample surfaces.
Negli ultimi tempi il recupero di diversi tipi di metalli dai rifiuti ha acquistato notevole interesse. Una delle ragioni è che i rifiuti, e in particolare i rifiuti elettronici, contengono metalli considerati strategici. Infatti, la disponibilità di questi metalli è limitata e diminuisce, poiché le risorse naturali sono limitate, e i loro prezzi variano in base ai mercati e alla politica di gestione dei paesi produttori. In realtà, i metalli strategici sono generalmente definiti come metalli che sono necessari per la difesa nazionale di un paese, ma sono minacciati da interruzioni di approvvigionamento a causa della modesta produzione nazionale. Tuttavia, la definizione di metalli strategici può includere anche i metalli che sono importanti non solo per la difesa nazionale, ma anche per le industrie che svolgono un ruolo importante nello sviluppo economico di un paese, ad esempio quelle legate all’energia, all’ambito aerospaziale, a quello delle telecomunicazioni, computer e tecnologia mobile. Per queste ragioni è diventato molto interessante ed urgente trovare un modo strategico per recuperare questi metalli dai rifiuti. In questo lavoro, è stato studiato il recupero di risorse da diversi rifiuti. In particolare, dopo l'introduzione e la descrizione dei sistemi sperimentali, nel Capitolo 3 viene discusso il recupero dell'oro, unitamente ad altri metalli (argento, rame e stagno) dalle schede di circuiti stampati (PCB) a fine vita. Si consideri che i metalli più pericolosi e preziosi sono contenuti proprio nei circuiti stampati. In particolare, è stato studiato un processo che comprende un attacco acido seguito dalla complessazione oro con tiourea o tiosolfato, due sostanze che potrebbero sostituire i ben più tossici cianuri, tipicamente utilizzati per la dissoluzione dell'oro. Inoltre, è stato esaminato l'effetto degli ultrasuoni durante la lisciviazione, al fine di verificare se il loro effetto consentisse di aumentare la resa d’estrazione. Infatti, negli ultimi anni, gli ultrasuoni sono stati studiati per assistere l'estrazione idrometallurgica dei metalli da minerale ma la loro applicazione industriale è ancora limitata, nonostante diversi vantaggi siano stati riconosciuti dalla loro applicazione: una maggiore liberazione dei metalli in tempi più brevi, minore concentrazione di reagenti necessaria e basse temperature di lavoro. Pertanto, l'uso di ultrasuoni potrebbe rappresentare un vantaggio per aumentare anche il recupero dei metalli preziosi dai rifiuti. Successivamente, è stato condotto uno studio per valutare il recupero dell'argento da pannelli fotovoltaici a fine vita e, più in generale, il processo più semplice e più economico per il completo recupero di risorse dai pannelli fotovoltaici. Sono stati quindi testati diversi metodi sia idrometallurgici che pirometallurgici e i risultati migliori si sono ottenuti combinando un trattamento pirometallurgico e tre idrometallurgici. I parametri di processo, come temperatura e durata del trattamento sono stati studiati e ottimizzati, sia per il riscaldamento che per i trattamenti chimici e i risultati di questo studio sono presentati nel Capitolo 4. Inoltre, visto che l'idea sembra economicamente valida, è stata anche testata a TRL 5 e i risultati emersi sono stati utilizzati per richiedere un finanziamento europeo. Infatti, è stato approvato il progetto "ReSiELP", che in tre anni dovrebbe costruire un impianto per esportare questa tecnologia a TRL 7. Successivamente, nel Capitolo 5, è stato studiato un modo per recuperare il tantalio dai condensatori a fine vita e neodimio da magneti permanenti. Per separare il tantalio dalla silice, è stato studiato e testato un trattamento con acido fluoridrico, mentre nel recupero del neodimio il processo noto in letteratura è stato modificato introducendo un trattamento con ammoniaca che aumenta la purezza del sale doppio di neodimio e sodio che viene recuperato. Dopo questi studi sull'estrazione dei metalli da rifiuti elettronici, è stato testato un metodo per aumentare il valore del materiale recuperato. Infatti, oltre al valore intrinseco di questi metalli, un ulteriore vantaggio potrebbe essere ottenuto recuperando questi metalli sotto forma di nanoparticelle, le quali presentano proprietà molto interessanti e promettenti in confronto ai corrispondenti materiali massivi. Le proprietà di quest’ultime sono ottiche, magnetiche, catalitiche, termodinamiche ed elettrochimiche. Inoltre, i nanomateriali possono fornire soluzioni alle sfide tecnologiche e ambientali nei settori della conversione energetica, della catalisi, della medicina e del trattamento dell'acqua. In quest’ottica, sono state prodotte nanoparticelle diverse utilizzando come materie prime le soluzioni in cui erano stati precedentemente ntrattati i rifiuti elettronici. In particolare sono state sintetizzate e caratterizzate nanoparticelle di ossido di stagno, argento, rame, ossido di rame, oro e ferro, ed i risultati dello studio sono presentati nel Capitolo 6. Tutte le nanoparticelle sono state sintetizzate utilizzando processi idrometallurgici e l'utilizzo di reagenti il più possibile ecocompatibili (quali l'acido ascorbico o lo sciroppo di glucosio) nonché la sperimentazione di una tecnologia, quali gli ultrasuoni, considerata ecologica e già testata durante la lisciviazione dei rifiuti elettronici. In questo caso, l'applicazione degli ultrasuoni ha consentito di ridurre le dimensioni delle particelle sintetizzate grazie all’effetto di cavitazione che generano nel liquido. Sono stati sviluppati diversi processi per produrre i sei tipi di nanoparticelle. I materiali ottenuti sono stati analizzati con plasma ad accoppiamento induttivo (ICP), microscopia a scansione e trasmissione elettronica (SEM e TEM), diffrazione a raggi X, diffrazione laser e spettroscopia UV. I risultati hanno dimostrato che i metodi sviluppati consentono di recuperare i metalli con elevata resa e di produrre nanoparticelle di ossido di stagno, argento, rame, ossido di rame, oro e ferro ad alta purezza e di dimensioni comprese tra 2 e 200 nm. Infine, è stata studiata anche un'applicazione interessante e innovativa per i metalli recuperati, in particolare argento e rame, ed i risultati riportati nel Capitolo 7 di questa tesi. In particolare, l'argento e la polvere di rame sono stati introdotti nel rivestimento di ossidazione elettrolitica al plasma. L'ossidazione al plasma elettrolitico (PEO), chiamata anche "Microarc Oxidation" (MAO), è una tecnica di rivestimento superficiale relativamente nuova ma che inizia ad essere impiegata nella produzione di rivestimenti ceramici d’ossido su leghe leggere quali l'alluminio, il titanio o il magnesio. Il trattamento PEO può migliorare le proprietà di resistenza alla corrosione e all'usura di questi metalli o conferisce diverse altre proprietà funzionali, tra cui diminuzione dell’attrito e protezione termica. Inoltre, il PEO può essere utilizzato come pretrattamento per fornire un substrato per altri rivestimenti. Il PEO deriva dall'anodizzazione convenzionale, ma presenta molti vantaggi, come ad esempio elevate proprietà dei rivestimenti di resistenza a usura e corrosione, l’impiego di elettroliti più rispettosi dell'ambiente e la possibilità di inserire nel rivestimento particelle provenienti dall'elettrolita. Il PEO dei metalli è un processo complesso che combina la formazione di film di ossido, la dissoluzione e la rottura del dielettrico: il campione, come anodo, è immerso in un elettrolita ed il processo impiega elevate tensioni e densità di corrente all'interno di un serbatoio che funge da catodo. A causa dell'elevata tensione che deve essere al di sopra del potenziale di rottura del dielettrico, durante il trattamento PEO vi sono micro-scariche anodiche persistenti sulla superficie. Queste micro-scariche di breve durata sono la chiave del processo; si muovono casualmente sulla superficie trattata provocando la crescita di un rivestimento ceramico d’ossido e permettendo di incorporare composti nel rivestimento. Negli studi presentati in questa tesi, le polveri di argento e rame sono state introdotte nel rivestimento PEO mediante aggiunta diretta nell'elettrolita per conferire rispettivamente l'effetto antimicrobico / antimicotico e antivegetativo ai campioni.

Orientador: Devaney Ribeiro do Carmo
Resumo: Este trabalho apresenta a preparação do óxido de grafeno (OG) através do Método de Hummers Modificado e subsequente modificação química de sua superfície com nanopartículas de pentacianonitrosilferrato(III) de cobre (OGCuNP). Os materiais obtidos foram caracterizados por diferentes técnicas, tais como: Espectroscopia na Região do Infravermelho com Transformada de Fourier, Espectroscopia Raman, Espectroscopia de Fotoelétrons Excitados por Raios-X, Microscopia Eletrônica de Varredura, Microscopia Eletrônica de Transmissão e Difração de Raios-X. O OGCuNP foi caracterizado por Voltametria Cíclica, empregando um eletrodo de pasta de grafite. O voltamograma cíclico do OGCuNP exibiu dois pares redox bem definidos com potencial médio (Eθ’) de 0,27 V e 0,77 V, para o primeiro e segundo par redox, que foram atribuídos aos processos redox Cu(I)/Cu(II) e Cu(II)Fe(II)(CN)5NO/Cu(II)Fe(III)(CN)5NO, respectivamente. O eletrodo de pasta de grafite modificado com OGCuNP apresentou resposta eletrocatalítica à três substâncias, a saber: hidrazina, isoniazida e N-acetilcisteína. Para a eletro-oxidação catalítica da hidrazina, o eletrodo de pasta de grafite modificado com OGCuNP apresentou resposta linear com concentração em um intervalo de 1,0×10-5 a 5,0×10-3 mol L-1 de hidrazina, com limite de detecção de 1,58×10-6 mol L-1. O eletrodo modificado também exibiu atividade eletrocatalítica para isoniazida, nos picos anódicos I e II, apresentando limite de detecção de 6,93×10-5 mol L-1 e de 2,16×10-5... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: This work presents the prepare of graphene oxide (OG) by the Modified Hummers Method, besides the chemical modification of its surface with nanoparticles of copper pentacyanonitrosylferrate(III) (OGCuNP). The materials obtained were characterized by different techniques, such as: Fourier Transform Infrared Spectroscopy, Raman Spectroscopy, X-Ray Photoelectron Spectroscopy, Scanning Electron Microscopy, Transmission Electron Microcopy and X-Ray Diffraction. The OGCuNP was characterize by the Cyclic Voltammetry technique, where the graphite paste electrode was used. The cyclic voltammogram of the OGCuNP exhibited two well-defined redox pairs with medium potential (Eθ’) 0,27 V and 0,77 V, for the first em second redox process, attributed to the redox processes of Cu(I)/Cu(II) and Cu(II)Fe(II)(CN)5NO/Cu(II)Fe(III)(CN)5NO, respectively. The graphite paste electrode modified with OGCuNP presented electrocatalytic response for three substances: hidrazine, isoniazide and N-acetylcysteine. For catalytic electro-oxidation of hidrazine, the grafite paste electrode modified with OGCuNP presented linear response in the concentration between 1,0×10-5 and 5,0×10-3 mol L-1 of hidrazine, with detection limit of 1,58×10-6 mol L-1. The modified electrode too exhibited electrocatalytic activity for isoniazide for the both anodic peaks I and II, and it presented detection limit of 6,93×10-5 mol L-1 and 2,16×10-5 mol L-1 in a concentration range of 6,0×10-5 to 6,0×10-3 mol L-1 and 6,0×10-4 to 7,0×... (Complete abstract click electronic access below)
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Vidros transparentes do sistema vítreo 0.95TeO2-(0.05-x)Sb2O3–xCuO contendo nanopartículas de cobre foi preparado com sucesso pelo método convencional de fusão – resfriamento dos materiais precursores, utilizando a rota redox do óxido de antimônio. Esta técnica de preparação de vidros permite a produção de nanopartículas metálicas durante a fusão dos materiais, através da reação de oxidação Sb3+ → Sb5+ + 2e-, que permite a redução de íons metálicos. A investigação estrutural foi realizada por calorimetria exploratória diferencial (DSC), difração de raios X (DRX) e espectroscopia Raman. Imagens de microscopia eletrônica de transmissão (TEM) e espectroscopia UV-visível evidenciaram a formação de clusters de nanopartículas de cobre cúbicas, distribuídas aleatoriamente em meio a matriz vítrea. A eficácia dos efeitos plasmônicos das nanopartículas de cobre promoveu a intensificação da fluorescência dos íons érbio. A interação da radiação excitante e amostra levou ao processo de excitação térmica, promovendo o aumento da população de níveis de energia específicos dos íons érbio, com consequente resposta óptica, evidenciada pela estrutura vibrônica presente no espectro de fluorescência dos vidros de teluritos contendo nanopartículas de cobre dopados com íons érbio. Além disso, os efeitos plasmônicos das nanopartículas de cobre na intensificação das emissões no infravermelho e conversão ascendente nos vidros de teluritos co-dopados com íons Yb3+/Ce3+/Er3+ sob excitação em 980 nm também foram investigados. As contribuições dos íons Yb3+ e Ce3+ também foram discutidas. A eficiência da ressonância do plasmon de superfície localizado (LSPR) das nanopartículas de cobre promoveu um melhoramento de cerca de 47% da emissão em 1550 nm dos íons Er3+. Além disso, o tempo de decaimento da transição Er3+: 4I13/2 → 4I15/2 aumentou em cerca de 50% na amostra contendo nanopartículas de cobre. Finalmente, os vidros de teluritos contendo nanopartículas de cobre apresentaram resultados interessantes quando utilizados como substratos para obtenção de espectros Raman intensificados por superfície (espectros SERS), sendo obtidos satisfatoriamente espectros SERS para soluções de 2,2’-bipiridina 1,0 × 10-5 mol.L-1 e do corante azul do Nilo 1,0 × 10-7 mol.L-1.
Transparent 0.95TeO2-(0.05-x)Sb2O3-xCuO glassy system containing copper nanoparticles were successfully prepared by the conventional melt quenching method of starting materials, using the antimony oxide redox route. This technique allows the production of metallic nanoparticles during melting, through the reaction Sb3+ → Sb5++ 2e-, which leads to the reduction of metallic ions. The structural investigation was carried out by differential scanning calorimetry (DSC), X ray diffraction (XRD) and Raman spectroscopy. Transmission electron microscopy image (TEM) and UV-visible spectroscopy evidenced the formation of cubic copper nanoparticles, randomly embedded in the glassy matrix. The effectiveness of the plasmonic effects of the copper nanoparticles provided the enhancement of the fluorescence of the erbium ions. The interaction between excitant radiation and sample led to the thermal excitation, which increased the population of specific energy levels of erbium ions, with consequent optical response into vibronic structure, as can be seen in the erbium-doped tellurite glasses containing copper nanoparticles. Furthermore, the plasmonic effects of the copper nanoparticles on the enhancement of the infrared and upconversion emissions intensities in the Er3+/Yb3+/Ce3+ co-doped transparent tellurite glasses under 980 nm laser diode excitation were investigated. The roles of Yb3+ and Ce3+ as sensitizers are also discussed. The effectiveness of localized surface plasmon resonance (LSPR) of the copper nanoparticles provided an improvement about 47% of the 1550 nm luminescence intensity of the Er3+ ions. Moreover, the lifetime of the Er3+: 4I13/2 → 4I15/2 transition increased around 50 % in the copper nanoparticle containing samples. Finally, the tellurite glasses containing copper nanoparticles showed interesting results as substrates for obtainment of surface enhanced Raman spectra (SERS spectra) and SERS spectra were satisfactorily obtained for 2,2'-bipyridine 1.0 × 10 -5 mol.L-1 and Nile blue dye 1.0 × 10-7 mol.L-1 solutions.

Les nanotechnologies sont en plein essor et mènent à l’incorporation de nanomatériaux manufacturés (NMM) dans les produits d’usage courant. La synthèse de NMM et l’utilisation des produits en contenant conduit au rejet dans l’environnement de NMM pour lesquels le risque n’est pas encore connu. Les propriétés physico-chimiques particulières des NMM rendent difficile l’évaluation de leur toxicité qui reste encore actuellement non complétement élucidée. Cette thèse est intégrée au projet ANR NanoSalt (2013 - 2017) et vise à évaluer le devenir et les effets de NMM de dioxyde de cérium et d’oxyde de cuivre sur deux espèces de bivalves représentatives des eaux douces (Corbicula fluminea) et des eaux marines (Scrobicularia plana). Les organismes ont été exposés à des concentrations réalistes de ces NMM à différentes étapes de leur cycle de vie et ce, à travers la mise en place d’expositions de plus en plus proches des conditions environnementales (micro- et mésocosmes). Actuellement, très peu d'études de nanotoxicologie ont adopté une approche de biologie moléculaire pour évaluer et comprendre les effets des NMM chez les invertébrés, particulièrement chez les espèces non séquencées. Un des objectifs de la thèse était d’utiliser l'approche de qPCR pour évaluer la perturbation de l’expression de gènes par les NMM. Ce travail a permis de déterminer le devenir et le comportement des NMM dans les différentes conditions d’exposition. L’évaluation des effets des NMM a été réalisée à différents niveaux biologiques (moléculaire, cellulaire, individuel). L’utilisation d’outils de statistiques multivariées s’est révélée particulièrement utile pour analyser les variations d’expression des nombreux gènes ciblés. L’approche multi-marqueurs sur plusieurs niveaux biologiques a permis l’intégration d’un grand nombre de données qui a généralement permis de départager les effets des différentes formes de NMM
Nanotechnology is constantly evolving and leads to the incorporation of engineered nanomaterials (ENM) into daily commercial products. The synthesis of ENM and the use of products containing those ENM leads to their release in the environment but the risk of ENM is not yet known. The particular physico-chemical properties of ENM makes the evaluation of their toxicity particularly difficult and still not completely solved now. This thesis is integrated to the ANR NanoSALT (2013-2017) and aims to evaluate the fate and the effects of cerium dioxide and copper oxide ENM in two bivalve species representative of freshwaters (Corbicula fluminea) and of seawaters (Scrobicularia plana). The organisms were exposed to realistic concentrations of these ENM at different stage of their life-cycle, and through the setting up of exposure increasingly closed to environmental conditions (micro- and mesocosms). Nowadays, few nanotoxicology studies have adopted an approach of molecular biology for the evaluation and the comprehension of ENM effects in invertebrates, and more particularly in non-sequenced species. One of the objective of the thesis was to use the qPCR approach for the evaluation of the gene expression perturbation by ENM. This work allowed to determine the fate and the behavior of ENM in the different exposure conditions. The evaluation of ENM effects has been done at different biological scales (molecular, cellular, individual). The use of multivariate statistical tools has been particularly useful for the analysis of the expression variations of the targeted genes. The multi-marker approach at different biological scales allowed the integration of a lot of data, which generally allowed us to differentiate the effects of the different forms of ENM

碩士
國立清華大學
材料科學工程學系
105
In response to challenges of energy crisis, global warming and climate change, electrochemical carbon dioxide reduction to produce chemicals or low-carbon fuels can serve as a means for carbon neutral and therefore has attracted much attention recently. The notorious greenhouse gas carbon dioxide can then become feedstock to synthesize numerous low-carbon fuels such as formate/formic acid, methanol, ethanol and others to provide renewable energy storage with high energy density forms. However, most of electrochemical reduction processes utilize precious metals (platinum or palladium) as electrode, or apply harsh temperature/pressure conditions which may limit the development of electrochemical reduction of carbon dioxide toward industrial applications. In this thesis work, we use copper nanoparticle decorated reduced graphene oxide (rGO), which is derived from one of the most abundant elements (i.e. carbon), as the electrochemical reduction electrode. The process can achieve carbon dioxide reduction with lower working potential. Electrode materials of platinum, palladium, rGO and copper decorated rGO as working potential were compared. The influences of reduction potential, electrode material and electrolyte acidity on production yield were discussed and characterized by scanning electron microscopy and gas chromatography. In addition, this process was conducted under ambient temperature/pressure without harsh condition or complicated equipments. The rGO/Cu electrode can achieve a cost reduction of 95% in average compared to precious metal electrodes (Pt and Pd). The work shall pave a new path toward developing carbon dioxide reduction electrodes and further promote development of electrochemical reduction process toward carbon dioxide derived low-carbon fuels.

Nanotechnology is a rapidly growing multidisciplinary field with a wide range of applications in science and industry for the synthesis and characterisation of novel nanoscale materials. Engineered nanoparticles have been developed as a result of recent breakthroughs in nanotechnology, providing a real and radically new possibility in a variety of sectors such as nanoscale electronics, optics, magnetics, energy, catalysis, biomedicine, clothing, cosmetics, and material science. Metal and metal oxide nanoparticles have a wide range of uses due to recent advances in nanoscience and nanotechnology in a variety of fields, research institutes, and enterprises. Green nanotechnology is piqueing researchers' interest in creating nanoparticles in a simple, cost-effective, less hazardous, and environmentally acceptable method. Copper oxide nanoparticles have gotten more attention than other metal oxides because of their unique characteristics and uses. Green synthesis of copper and copper oxide nanoparticles proved more cost-effective and more environmentally friendly than many other physical and chemical approaches. The production of copper nanoparticles utilising the leaf extract of Parthenium hysterophorus is described in this study. UV-VIS spectrophotometer, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), Dynamic light scattering (DLS), and X-ray diffraction (XRD) techniques were used to characterise the biosynthesized copper nanoparticle.

The goal of this project is to fabricate a low cost chemical vapor deposition (CVD) setup and synthesize hybrid nanomaterials i.e. copper oxide (CuO)-CdX (X=Se, S) nanoparticles decorated core-shell heterostructure. The synthesized hybrid nanomaterials have been fabricated into a device (photodetector) for the measurement of current-voltage characteristics in dark and under UV illumination. Furthermore, the growth model for the formation of core-shell heterostructure has also been discussed in this project. Chapter-I narrates about the fundamentals of materials, nanomaterials and hybrid nanomaterials. In this chapter, the importance, properties, application of nanomaterials have been outlined. Moreover, the properties and morphology and corresponding application are highlydependent on the synthesis methods. Chemical vapor deposition (CVD) technique is found be one of versatile among all other preparation methods. The motivation by addressing the challenges have been discussed thoroughly. Chapter-II describes the fabrication of a low cost CVD setup. For the fabrication of CVD setup, a three-zone horizontal furnace, reaction tube, a rotary van pump and three mass flow meters have been procured. A liquid precursor handling system and a reaction chamber which has fitted with two couplings have been designed. All these subcomponents have been assembled and integrated into a single unit CVD setup. Chapter-III discusses about the detailed experimental procedure for the synthesis of CuO nanowires-CdX (X=Se, S) nanoparticles decorated core-shell heterostructure. For the synthesis of CuO-CdX (X= Se, S) heterostructure nanomaterials, CuO nanowires have been synthesizedfirst by using thermal oxidation of Cu foil in air at 5000C for 5 hours. These CuO nanowires grown on cu foils have been used for the synthesis of heterostructure by using the fabricated CVD. All these materials i.e. CuO nanowires, CuO-CdSe & CuO-CdS heterostructure have been characterized by field emission electron microscopy (FESEM) attached with energy dispersive spectroscopy (EDS), x-ray diffraction (XRD), transmission electron microscopy (TEM) attached with high resolution TEM (HRTEM) and selected area diffraction pattern (SAED), RAMAN spectroscopy & UV-Vis spectroscopy. Moreover, these materials have been fabricated intoa photodetector for the measurement of current-voltage characteristics in dark and under UV illumination. Chapter-IV describes the detailed material characterization of CuO-CdSe heterostructure nanomaterials. The FESEM image of CuO nanowires reveals the formation CuO nanowires stretching out of the surface. The surface of CuO nanowires is very much smooth and impurity free. Formation of beaded like structures of CdSe is found to be attached intermittently on the surface of CuO nanowires. The presence of Cd, Se elements in the materials has been confirmed by EDS. However, the formation of these bead structure is well confirmed TEM along with the formation of core-shell heterostructure. XRD, HRTEM, SAED pattern confirms the crystalline nature of the materials. Raman spectroscopy further confirms the presence of CdSe in the CVD synthesized materials. Using UV-Vis spectroscopy measurement the band gap is found to be ~2.2eV for CuO nanowires and 3.96eV for CuO-CdSe heterostructure. Chapter-V discusses about the material characterization of CuO-CdS nanomaterials. From FESEM image, the rough surface of CuO-CdS is found by FESEM observation which is attributed to the deposition of CdS nanoparticles thoroughly on to the surface of CuO nanowires during preparation of CuO-CdS core-shell structure by CVD process. The presence of Cd, S elements in the materials has been confirmed by EDS. The formation of core-shell heterostructure has been well verified by TEM. The crystalline natures of the materials have been confirmed by XRD, HRTEM, and SAED pattern. Raman spectroscopy further confirms the presence of CdS in the CVD synthesized materials. The band gap is found to be ~3.73eV for CuO-CdS heterostructure as measured by UV-Vis spectroscopy. Chapter-VI discusses about some general trends in growth mechanism of hybrid nanomaterials and a probable growth mechanism of the present research work has been suggested as deduced from experimental characterization. The probable growth mechanism for CuO-CdSe is found to be gas phase adsorption, whereas surface diffusion and gas phaseadsorption growth mechanism for CuO-CdS has been suggested. However, the exact growth mechanism is yet to be established that needs further investigation in detail. Furthermore, the current-voltage characteristics of the fabricated photodetector have been measured by Keithley source meter 2400. The measured current for the CuO is 1.4μA at bias voltage 3 Volt. Similarly, the dark current measured for the CuO-CdSe is 11 μA. However, the current increased to 33μA under UV illumination at the biasing 3V. For CuO-CdS, the current is found to be 10.8μA and increased to 23.8 under UV illumination at the biasing 5V. The increase in photocurrent attribute because of the effective charge separation in electron-hole in the heterojunction, which has been discussed thoroughly in the chapter by using band diagram.

碩士
國立清華大學
化學工程學系
104
We report a systematic study of gas-phase controlled synthesis of copper oxides-based hybrid nanoparticles for catalytic CO oxidation. The complementary physical, spectroscopic and microscopic analyses were conducted to obtain a better understanding of the material properties, including particle size, crystallinity, elemental composition, and oxidation state. Results showed that the synthesized nanoparticles exhibited highly durable catalytic activity and stability, also the particle size, crystallite size, and chemical composition were tunable by choosing suitable chemical compositions of precursors and temperatures. The crystallite size of CuO influenced the reducibility of CuO by CO and the subsequent catalytic activity of CO oxidation. The hybridization process of CeO2 and CuO induces the formation of new active sites at the Cu-Ce-O interface, which enhances reproducibility of CuO and the catalytic activity. However, the reproducibility of CuO and catalytic activity were considerably decreased when CeO2 was replaced with the inert Al2O3. This work describes a prototype method to form highly pure and well-controlled hybrid nanocatalysts, which can be used to establish the correlation of material properties versus reducibility and subsequent catalytic activity for energy and environmental applications.

碩士
國立中正大學
化學暨生物化學研究所
105
The main focus of this thesis is to prepare copper and cuprous oxide nanoparticles by thermal decomposition of organometallic precursor, namely Cu(hfac)2. Copper nanoparticles in oleylamine are prepared, and cuprous oxide nanoparticles are obtained in dodecane. A variety of surfactants have been used in order to get the nanoparticles of the desired shapes and sizes distribution. In order to study the uniformity and dispersion of nanoparticles, we attempt to use a variety of surfactants and to vary the experimental factors such as the precursor to surfactant molar ratio, reaction temperature. We use amines as surfactant to obtain well-dispersed copper nanoparticles with five different sizes(12、23、26、60 and 70 nm) in oleylamine solvent system. And we use amines as surfactant to obtain well-dispersed cuprous oxide nanoparticles with four different sizes(40、50、70 and 120 nm) in dodecane solvent system. In addition, we use thiols as surfactant to obtain cuprous sulfide nanoparticles. keyword:Copper, Cuprous Oxide

碩士
國立中正大學
化學暨生物化學研究所
100
The main focus of this thesis is to prepare cuprous oxide nanoparticles by thermal decomposition of organometallic precursor, namely (hfac)Cu(COD). The precursors were dissolved in the organic solvent and were reduced to produce copper nanoparticles then to stand in air after being oxidized to the cuprous oxide nanoparticles. Variety of surfactants have been used in order to get the nanoparticles of the desired shape and size distribution. Some factors like precursor to surfactant molar ratio, reaction temperature, reaction time are modified in order to study the uniformity and dispersion of nanoparticles. We use different amines as surfactants to generate 9 nm and 10 nm cuprous oxide nanoparticles and to generate 5 nm cupric oxide nanoparticles. We use polyvinylpyrrolidone as surfactant to generate 15 nm cuprous oxide nanoparticles. In structural analysis, we observed the shape and the size of nanoparticles by transmission electron microscopy (TEM). We used energy dispersive spectroscopy (EDS), X-ray powder diffractometer (XRD) and electron diffractometer to identify composition of nanoparticles. The X-ray photoelectron spectroscopy was used to confirm the composition of nanomaterials. In our study, we confirmed these products are Copper(Ι) oxide.

碩士
國立中山大學
化學系研究所
101
CuO is a narrow band gap p-type semiconductor and has been recognized as an essential material for diverse practical applications, including catalysis, batteries, magnetic storage media, solar energy conversion, gas sensing, and field emission. In recent years, copper oxide reported by different synthetic methods with different shapes and sizes, for example: nanorods, nanowires, nanotubes ... and so on. In this experiment, we synthesize copper oxide precursor by using the precipitation method and then treated by plasma to convert it into copper oxide. XRD、XPS and TEM were used to characterize the structure. Copper oxide will be applied to the two parts in this article. The first part, copper oxide were used as a heterogeneous Fenton-like catalyst to degrade methylene blue, and a UV spectrometer monitor the heterogeneous Fenton-like reaction. The generated products are monitored by a mass spectrometer during the reaction. We find the optimal reaction conditions by adjusting the initial pH of aqueous solution. Experimental results show the optimum reaction conditions were pH value between 5 to11. Raman spectroscopy is used for surface science. Recently, Surface-enhanced Raman Scattering （SERS） in surface science become an important and interesting technology. The second part of the experiment, we synthesized Ag / CuO particles as SERS substrate by adjusting the concentration of silver nitrate and reaction time. In our work, 4-ATP was selected as the probe molecule to investigate the SERS properties of the obtained substrates. Compared to pure copper oxide or pure silver as SERS substrates, Ag/CuO particles can effectively enhance the ATP signal, and the detection limit of up to 10-5 M.

碩士
明志科技大學
化學工程系碩士班
105
In this study, chitosan/graphene oxide gel beads were used for the adsorption of Cu(II) ions. The chitosan/graphene oxide solution was added dropwise into a gently agitated 1 M NaOH solution through precision tubing using a tubing pump. Adsorption of Cu(II) ions onto chitosan/graphene oxide gel beads was pH-dependent.The result showed that adsorption data were correlated well with Freundlich isotherm model. The maximum adsorption capacity derived from Langmuir isotherm was 134.6 mg/g. The value of RL in the range of 0 to 1 at all initial concentration confirms the favorable uptake of the Cu(II) ion process. The Freundlich isotherm, predicts n, representing adsorption favorability as greater than one, indicating the adsorption intensity is favorable at high concentrations. The adsorption kinetics were described by the pseudo-second order kinetic model and the correlation coefficient (R2) is greater than 0.99. These correlation results suggest that the adsorption of Cu (II) ions onto chitosan/graphene oxide gel beads exhibits pseudo-second order kinetics. The FTIR was used to verify functional groups of the prepared brads, and SEM was used to observed the surface and inside morphology of the prepared beads. For the catalytic reduction of rhodamine B, an appropriate amount of the Cu(II)/chitosan/graphene oxide composite was added to the aqueous solution containing methylene blue with NaBH4. The blue color of solution quickly vanished, indicating the reduction of methylene blue. The copper nanoparticles/chitosan /graphene oxide composite shows high catalytic and adsorption performance in reduction of methylene blue, and the results for the application of copper nanoparticles/ chitosan/graphene oxide composite are evaluated in dye treatments. The cost of this material is much lower than that of precious metals, and also has good catalytic effect.

碩士
逢甲大學
材料科學與工程學系
106
In this study, tin oxide (SnO2) nanoparticles were synthesized by the reaction of SnCl2·2H2O in ethanol via sol–gel method. Copper ion was adsorbed onto the surface of SnO2 nanoparticles for the p-n heterojunction formation by using the precipitation and SILAR (successive ionic layer adsorption and reaction) method, respectively. The effects of copper content on the properties such as microstructure, electrical behavior, and response toward CO gas concentration of SnO2 nanoparticles were investigated as a function of copper ion addition by the analyses of XRD, SEM, TEM, PL, UV-vis and CO gas sensing measurement. The experimental results represented that the copper ion absorbed successfully onto the surface of SnO2 nanoparticles, after calcining the copper ion reacted to CuO. As SnO2 gas sensor being decorated with 4 mol% CuO exhibited the best sensing performance at low operating temperature. The CuO-decorated SnO2 gas sensor with a nanoparticles microstructure can provide enough reaction position for CO sensing. The addition of p-type copper oxide to the SnO2 generated a p-n junction, which can effectively enhance the difference between the resistance of semiconductor gas sensor in the air and the CO reducing gas atmosphere. The CuO-decorated SnO2 gas sensor showed comparable and good sensing response even under a very low concentration (10 ppm) of CO gas at room temperature.

碩士
義守大學
化學工程學系暨生物技術與化學工程研究所
105
In this study, we aimed to develop a highly sensitive and selective room temperature ammonia sensors, and it was achieved by using a polyamine-reduced graphene oxide nanocomposite sensing layer. The sensing material comprised polyaniline and reduced graphene oxide because polyamine could sense ammonia at room temperature and reduced graphene oxide exhibited good electric properties. Compared with different materials, the response of composites at room temperature is was higher then polyaniline ammonia sensor . The ammonia sensing linear range form 200 ppm to 250 ppb. . Temperature effect and flow rate effects were also studied. Long-term stability of the nanocomposite ammonia sensor was evaluated. The experimental results suggested that this nanocomposite sensor exbilted high sensitivity, selectiviety, and stability for ammonia sensing at room temperature.

碩士
國立中興大學
化學系所
104
Photothermal therapy (PTT) was an innovate therapy that received many attentions due to its low invasive property. However, the vast phototheraml agents had biocompatibility problem especially copper based series agents. We focused on improvement the Cu@Cu2O stability in culture medium due to its high affinity and dissolution rate too fast that led to limitation in vitro application. Therefore, we attempted to different approaches to protect the Cu@Cu2O or Cu@Cu2O@HA modification on that NPs surface. However, these approach was modified to the Cu@Cu2O or Cu@Cu2O, the stability no obviously was improved. Eventually, we directly added another metal to reform the bimetallic nanocomposites (NCs). In addition, The Cu-Au bimetallic NCs exhibited excellent photothermal performance that remain original similar photothermal property due to their strong near-infrared (NIR) absorption property. The size of Cu-Au bimetallic NCs detected by TEM about 10 nm and this size could through passive targeting due to enhance permeability and retention (EPR) effect. Moreover, improvement stability in culture medium of the Cu-Au bimetallic NCs. In vitro experiment indicated Cu-Au bimetallic NCs without 808 nm laser irradiation reveal low cytotoxicity, whereas, the almost 20% cells survival with laser irradiation in cancer cells. Consequently, the bimetallic NCs not only possessed excellent photothemral efficiency but increase biocompatibility via reducing the copper ions release in biomedical application.

Five commercial metal oxide nanoparticles (CuO, SiO2, Fe2O3, TiO2 and Al2O3) have been individually screened for mercury removal in a batch reactor under bicarbonate buffered and non-buffered aqueous solutions (DI water). Copper oxide was then selected for surface modification to enhance mercury removal. The surfaces of both laboratory prepared and commercially available copper oxide nanoparticles were treated with 1-octanethiol to produce copper sulfide and/or copper alkanethiol nanoparticles. The resulting particles were characterized using X-Ray Fluorescence(XRF), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The novel nanoparticles demonstrated very high mercury removal (> 99%) from both the buffered and non-buffered aqueous solutions.

碩士
國立雲林科技大學
化學工程與材料工程系
105
Commercial copper oxide nanoparticles (CuO NPs) as catalyst were tested for the degradation of Rhodamine B (Rh B) in heterogeneous Fenton-like process. The CuO NPs were characterized by SEM, EDS, XRD, FTIR and DRS. The effect of different reaction parameters on RhB degradation was also studied. The experimental results showed that the CuO/H2O2 can effectively produce HO．, and the range of pH values (pH 4 ~ 8) which the CuO was appropriate was found to be much wider than that of the classic Fenton's reagent. The optimal conditions obtained by orthogonal experimental design for complete degradation of 100 mL, 5 ppm Rh B solution at 28℃ were as follows: pH 6,15 mg CuO, 3 mL H2O2 and reaction time 4 hrs. Besides, the ANOVA analysis also indicated that pH had the largest influence on the degradation ratio of RhB, and the interaction terms of pH and CuO dosage, pH and H2O2 dosage were obvious. In addition, increasing temperature in the range of 25-45 oC increased the rate of Rh B degradation. Effect of the presence of inorganic anions (carbonate and phosphate) on dye degradation was also investigated, and the anions retarded Rh B decolorization in the following sequence: H2PO4- > HCO3- > HPO42- > H2CO3*. Moreover, the CuO/H2O2 system was found to be also satisfactorily applicable for degrading methylene blue and methyl orange. Finally, after optimization, the reaction time for nearly complete degradation of 100 ppm Rh B could be reduced from 33 hrs to 8 hrs.

碩士
國立中山大學
化學系研究所
107
In recent years, the drug resistance of pathogens to antibiotics has increased continuously, causing severe health problems. Through combining the technology of nanomaterial science and the inherent antibacterial activity of metal oxides, many studies developed innovative antibacterial methods by utilizing metal oxide nanoparticles. This study uses simple hydrothermal synthesis to synthesize copper oxide. And through adding different polymer modifiers to achieve surface modification and optimize the antibacterial efficiency of the original copper oxide. Additionally, The study uses Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Fourier-transform Infrared Spectroscopy (FTIR), and Zeta Potential Analyzer to confirm the characteristics of copper oxide. The bacterial pathogen selected in the experiment is E.coli. We tested on different modified copper oxide for antibacterial activities. By using the Microplate Spectrophotometer to measure the bacteria’s optical density value, the result shows that the copper oxide modified by the polymer is significantly better than the copper oxide without any modification. Among them, the PDA-modified copper oxide performs the best, with the inhibition rate of 85%. The overall results show that the antibacterial mechanism of this experiment is the internalization of nanoparticle and nanoparticle accumulation on bacterial membrane surface. Finally, we prove that copper oxide nanomaterial has a huge potential in synthesizing simple and low-cost inorganic antibacterial agents and its main antibacterial mechanism can be revealed.

A Dissertation submitted to the Faculty of Science, School of Chemistry, University of Witwatersrand in fulfillment of the requirements for the degree of Master of Science. Johannesburg 2014
The resin-gel method of synthesis successfully produced compounds of mixed metal oxides of copper titanium oxide powders of the form CuxTiyOZ with different compositions. These include Cu3TiO5, Cu3TiO4, Ti3Cu3O, Cu2Ti4O, Cu2Ti2O5 and Cu2TiO3. Heat-treatment of the powders at 300°C, 500°C, 700°C and 900°C for 1 hour was performed to determine the full composition/temperature phase diagram. The target particle size was in the 10- nanometer range, and for most of the samples, this size was achieved. Powder xray diffraction and transmission electron microscopy were the main techniques used to study the crystallization of these materials and their transformation to other polymorphic phases under different temperatures. Phase-match, particle size analysis and TEM imaging determined the properties and characteristics of the respective crystallographic phases of these materials. TEM analysis showed that some powders agglomerated while others exhibited both regular and irregular morphologies and polydisperse particle size distribution. Only a single unique phase was identified, but its structure could not be determined.

碩士
義守大學
生物技術與化學工程研究所碩士班
98
Reverse micelles-synthesized copper nanoparticles supported on cerium oxide for selective CO oxidation in rich hydrogen is studied in this work. To prepare the catalyst, the copper nanoparticles were destabilized from the microemulsion, and thus quickly adsorbed onto the cerium oxide powder. XRD patterns exhibited the characteristic peaks of cerium oxide only. No diffraction lines corresponding to those of copper species were detected, indicating very good dispersion of the nano-sized copper on the carrier. Activity test of the 0.5 wt% CuO/CeO2 catalyst (0.01 M copper ion concentration) showed that 30% conversion of CO was attained at 80℃. The CO selectivity remained almost at 100% for temperatures below 110℃, indicating that hydrogen at these temperatures would not affect the CO oxidation reaction. However, when the temperature exceeded 110℃, hydrogen was energetically enough to be dissociatively adsorbed on the catalyst surface to compete with CO for interfacial oxygen ions, thus inhibiting the activity of CO oxidation. CO was not easily converted into CO2 under the influence of hydrogen. When temperature exceeded 130℃, the hydrogen was ‘lighted off’, though the light-off was not very significant so that the selectivity declined slowly. This temperature depends on the interaction of CO and H2 for interfacial oxygen ions. It was observed, from the study of the competitive oxidation of CO and H2 at temperatures higher than that of hydrogen ‘light-off’, that CO exhibited a higher oxidation activity in the competitive oxidation of CO and H2, thereby limiting the accessibility of hydrogen to oxygen. The effects of different concentrations of copper ions and copper loadings were investigated also. It was found that much better oxidation activity could be obtained from the catalyst of 2 wt% CuO/CeO2 prepared by 0.01 M copper ion concentration. The conversion of CO was 46% at 80℃, while at 120℃ the CO conversion was able to reach 100% and the selectivity still maintained at about 80%. The performance of the copper catalyst synthesized in this work is comparable to that of the precious metal catalyst, yet with economic advantages.

碩士
國立臺灣科技大學
化學工程系
106
In recent years, a lot of people have suffered from diabetes disease. Humans have been attention to control of blood sugar by themselves in a variety of means, including using a glucose sensor. In order to prepare a non-enzymatic glucose sensor with high sensitivity, this study used CuxOy nanoparticles as an active electrocatalyst due to its high conductivity, photoelectric properties, relative stability, and also antibacterial activity. Further, the synthesized CuxOy nanoparticles were immobilized on the surface of gold electrodes (AuEs) to establish rapid, accurate, and high selectivity glucose sensor. The common method for preparing CuxOy nanoparticles is a liquid phase method, in which the nanoparticles are synthesized by using a reducing agent, capping agent, and/or surfactant. In addition, the preparation of nanoparticles by this method is time consuming and the used chemical agents are also harmful to the environment. Therefore, microplasma has recently emerged as an attractive and method to synthesize various metal and metal oxide nanoparticles. This method has also the potential to prepare various nanoparticles in a one-step and short time without adding either reducing or capping agents, and also surfactants. This thesis is comprised of three parts: the first parts focused on the optimization of the concentrations of NaCl for generating stable microplasma system by oscilloscope. The second part was to fabricate copper oxides nanoparticles (CuxOy-NPs) with different concentrations of ascorbic acid (AA) in a 25 mM of NaCl solution. The physical and chemical characteristics of the as-prepared CuxOy-NPs were examined by field-emission scanning electron microscope (SEM), X-ray diffraction (XRD), and UV-Vis spectroscopy. Meanwhile, the third parts were divided into three sections: (i) detection of hydrogen peroxide (H2O2) by modifying different concentrations of CuxOy-NPs on disposable gold electrode (AuE) and (ii) optimization of the concentration of CuxOy-NPs decorated on the AuE. The results showed that an optimized concentration of 5 mg/ml CuO/AuE or Cu2O/AuE to detect H2O2 in 0.1 M PBS (pH=7.4) at -0.3 V vs. Ag/AgCl gave the linear detection range from 0.1 to 10 mM and highest sensitivities of 1470 μA mM-1 cm-2 and 857 μA mM-1 cm-2. And (iii) the nonenzymatic detection of glucose by the optimized concentration of CuxOy/AuE in 0.1 M NaOH (0.1 M KCl) at 0.5 V vs. Ag/AgCl. The results demonstrated that the best sensing platform for glucose detection was CuO/AuE. The linear concentration range of glucose detection was from 0.02 to 5 mM and 5 to 12 mM with the sensitivity values of 3.5 mA mM-1 cm-2 and 1.01 mA mM-1 cm-2. In this work, the fabricated CuxOy/AuE sensor was modified by different concentrations of Nafion to avoid interference from several electroactive species including AA and uric acid (UA) present in human blood toward glucose detection. The results showed that the current responses increased when adding AA and UA into 0.1 M NaOH (0.1 M KCl) without Nafion on CuxOy/AuE. However, the current responses did not show appreciable changes during the addition of AA and UA after 0.5% Nafion was casted on CuxOy/AuE. Therefore, 0.5% Nafion was selected as the optimized concentration for anti-interference studies to enhance the selectivity of CuxOy/Au sensing platform toward glucose.

碩士
國立中正大學
化學所
98
We have successfully synthesized copper(II) aminodipyridylphosphine oxide complex [HO(CH2)11N(H)P(O)(2-py)2]Cu(OTf)2 (3) and gold nanoparticles-supported catalyst Au NPs-S(CH2)11N(H)P(O)(2-py)2Cu(OTf)2 (10) in quantitative yields. The complex 3 was synthesized by direct reaction of Cu(CF3SO3)2 and HO(CH2)11N(H)P(O)(2-py)2 (2) in a mixed solvent system of CH2Cl2 and CH3CN (v/v = 10:1) at 25 oC for 12 hours. The resulting solution was concentrated and a portion of ether acting as diffusion solvent was added at 0 oC to give [HO(CH2)11N(H)P(O)(2-py)2]Cu(OTf)2 (3) as green precipitates. The moisture- and air-stable green powdered products were obtained by decanting off the supernatant followed by drying under vacuum. The complex 3 was paramagnetic and could be characterized by IR, FAB-MS, EPR, XPS, EA and X-ray crystallography. The octanethiolate protected gold nanoparticles (Au NPs), RS-Au (8, R = C8H17), were functionalized with HS(CH2)11N(H)P(O)(2-py)2 (7) by the ligand-exchange method to give mixed thiolates-covered Au NPs, RS-Au-L (9), where L = HS(CH2)11NHP(O)(2-py)2. Afterward, a mixture of Cu(CF3SO3)2 and 9 in a mixed solvent system of CH2Cl2 and CH3CN (v/v = 5:1) was allowed to stir at 25 oC for 16 hours to give the hybrid catalyst RS-Au-L-Cu(OTf)2 (10). The Au NPs 10 was also paramagnetic and was characterized by IR, UV, EPR, XPS, TEM and AA spectroscopies. The complex 3 and Au NPs 10 were proved to be highly effective catalysts for a series of annulation reactions of para-substituted phenols and/or naphthols with 1,3-dienes. With a catalyst loading of 5 mol% of 3 or 10, the annulation reactions could be completed in 18 hours in CH2Cl2 at 50 oC to give desired products in 60-95% yields. We also found that the reactivity phenols and/or naphthols with electron-rich substituents provided better reactivity in the following order: R = p-(CH3)3CH &gt; p-OCH3 &gt; p-CH3 &gt; H. In contrast, when electron-withdrawing substituents such as Br- and I- were present the reactivity decreased as expected. In addition, by using (bmim)PF6 (bmim = 1-butyl-3-methylimidazolium) as the green solvent, 3 or 10-catalyzed annulation reactions of para-substituted phenols and/or naphthols with 1,3-dienes could be further accelerated under 600 W microwave irradiation conditions to give desired products in 85-94% yields in just 50 seconds. In the presence of our target hybrid catalyst 10 (20 mol%), the annulation reactions of p-cresol with isoprene were carried out at 50 oC and in a mixed solvent system of CH2Cl2 and CH3CN (v/v = 10:1) to give the corresponding products with &gt;95% yield in 3 hours. The catalyst 10 could be quantitatively recovered and effectively recycled more than 14 cycles without any significant loss of activity. However, the recycling of catalyst 3 showed that the yield dropped from 99% in the 1st cycle to 46% in the 3rd cycle.

碩士
國立臺北科技大學
化學工程研究所
96
Part I：A novel and easy fabrication of MPS-nano Ag/nafion film modified sensor has been constructed based on the self-assembly of 3-Mercapto-1-propane sulfonic acid (MPS) over a pretreated glassy carbon electrode (GCE) followed by the electrochemical depositions of Ag nano particles (nano Ag) with manual nafion coating (5 μL). Further the MPS-nano Ag/nafion film modified semiconductor indium tin oxide electrodes (ITO) were examined by using SEM and AFM techniques. From these analyses, it was found that the nano Ag particles were uniformly deposited on the MPS layer and the sizes were in the range of 35 to 70 nm, respectively. The MPS-nano Ag/nafion film modified GCE were characterized by using electrochemical impedance spectroscopic studies (EIS). Further the nano Ag/nafion film deposited onto the self assembled surface of MPS exhibited excellent electrocatalytic activity for the detection of oxygen at a reduced potential (-0.4 V) with good sensitivity in a wide concentration range. Furthermore the MPS-nano Ag film/nafion on GCE showed good electrocatalytic activity for the detection of neurotransmitters like epinephrine, norepinephrine, and dopamine by using differential pulse voltammetric technique (DPV). In addition the proposed MPS-nano Ag/nafion film showed obvious results for the detection of epinephrine, dopamine from injection solutions in presence of higher concentrations of ascorbic acid (from vitamin C tablets) for real sample analysis and the results were found satisfactory. Finally the proposed MPS-nano Ag/nafion film sensor is easy to fabricate and has the advantages of good stability, reproducibility, and shows rapid response for oxygen reduction and detection of catecholamine neurotransmitters individually and in mixture. Part II：Electrochemical oxidation of luminol was performed on nanopowder ZnO modified glassy carbon electrode (GCE). Compared to bare GCE, nano-ZnO modified electrode promoted the high oxidation current which consequently results poly(Luminol) film on nano-ZnO surface.This hybrid film noted as nano-ZnO/Poly(Luminol),(Zn-PL).AFM and SEM results revealed that nano-ZnO/poly(luminol) covered the electrode surface and the particle sizes of ZnO were 70 – 120 nm. Electrochemical studies proved that ZnO-PL hybrid film modified electrodes is electroactive in neutral buffers solution and showed excellent electrocatalytic activities towards ascorbic acid at lower potential. Compared to bare and only PL/GCE, ZnO-PL showed higher catalytic current. When apply a light on the ZnO-PL electrode surface for 30 mints, 0.5 times higher catalytic current was observed which shows the photocatalytic effect of ZnO particles. Using amperometry, linear range and detection limit of ascorbic acid was evaluated. This new method can be applied for detection of ascorbic acid in real samples. We also demonstrated the determination of ascorbic acid in commercial tablets with good results. Part III：A new modified electrode has been developed based on copper nanoparticles/zinc oxide films. In this method, copper nanoparticles (Cu-NPs) electrochemically deposited onto zinc oxide film modified electrode. Atomic force microscope, scanning electron microscope and x-ray diffraction studies revealed that copper and zinc oxide films were attached onto the electrode surface. This new ZnO /Cu-NPs coated glassy carbon electrode showed excellent electrocatalytic activities towards glucose in 0.1 M NaOH solution. Using amperometric method, linear range and detection limit have been explored.

Przedmiotem rozprawy doktorskiej było zastosowanie biofilmów bakteryjnych do projektowania hybrydowych układów bioelektrokatalitycznych zdolnych do redukcji dwutlenku węgla. W pracy wykorzystano bakterie Yersinia enterocolitica (bioserotyp 2/O:9), ze względu na duże zdolności adaptacyjne i możliwości przeżycia tego gatunku w zróżnicowanych niszach ekologicznych, co stanowiło pierwszą znaną próbę jego użycia w tak inertnym procesie elektrochemicznym. W rozprawie zaproponowane zostały systemy biokatalityczne aktywne w reakcji elektrochemicznej i fotoelektrochemicznej konwersji CO2, zawierające matrycę biologiczną Y. enterocolitica oraz nanocząstki metali przejściowych lub ich związki i kompleksy, pełniące rolę centrów aktywnych katalitycznie. Elektrochemiczna redukcja CO2 jest alternatywną metodą konwersji dwutlenku węgla do przydatnych substancji chemicznych i materiałów paliwowych. Cząsteczka CO2 jest wyjątkowo stabilna, więc jej elektroredukcja charakteryzuje się dużym nadpotencjałem reakcji. Wyzwanie stanowi też konkurencyjna reakcja wydzielania wodoru, o znaczącym wpływie na selektywność i dynamikę redukcji CO2. W poszukiwaniu wydajnych i selektywnych układów katalitycznych aktywnych w elektroredukcji CO2 badane są nanocząstki metali i ich związki, a coraz częściej dostrzegany jest też potencjał układów biologicznych: biofilmów bakteryjnych. Te złożone trójwymiarowe wielokomórkowe struktury cechują się dużą trwałością w szerokim spektrum warunków otoczenia i umożliwiają wytwarzanie materiałów katalitycznych pracujących w normalnej temperaturze i pod ciśnieniem atmosferycznym. Uwodniona matryca biofilmów pozwala łatwo przemieszczać się jonom elektrolitu na elektrokatalitycznej granicy faz – w efekcie stanowią one pewnego rodzaju jonowo-przewodzący hydrożel wspomagający procesy redoks. Struktura i właściwości biofilmów stwarzają możliwość wykorzystania ich jako matryc do unieruchamiania aktywnych katalitycznie cząsteczek w wytwarzanej przez nie na powierzchniach elektrod warstwie, stabilizację fotoelektrochemicznie czynnych materiałów półprzewodnikowych, a także dekorowania biofilmów różnymi związkami reaktywnymi. W pracy porównano wpływ biofilmu na aktywność katalityczną nanocząstek metali przejściowych (Pd, Pt, Ru, PtRu) w procesie konwersji CO2. Zaprojektowano także hybrydowy system bioelektrokatalityczny aktywny w kierunku redukcji CO2, bazujący na nanocząstkach Pt osadzonych na nośniku biologicznym – biofilmie Y. enterocolitica wspieranym polimerem przewodzącym (polianiliną) oraz wielościennymi nanorurkami węglowymi. Zaproponowano również unikalną metodę wprowadzenia i zdyspergowania organometalicznego kompleksu rutenu (II) w warstwie biologicznej, poprzez modyfikowanie podłoża płynnego do hodowli bakterii roztworem tego związku (suplementowanie, „dokarmianie” bakterii, ang. feeding). Zastosowano też biofilm (wraz z umiejscowionymi w jej przestrzeni cząsteczkami kompleksu rutenu (II)) w roli warstwy ochronnej, stabilizującej nietrwały półprzewodnik typu p – tlenek miedzi (I). Zaproponowany układ katalityczny wykazuje aktywność w procesie fotoelektrochemicznej redukcji CO2 i stabilność w warunkach eksperymentalnych. Rozprawa doktorska obejmuje takie zagadnienia jak: projektowanie wymienionych systemów aktywnych katalitycznie, ocenę ich przydatności elektrokatalitycznej, sprawdzanie struktury badanych układów, ich stabilności, żywotności bakterii w błonie biologicznej oraz zdefiniowanie roli pełnionej przez biofilm bakteryjny w analizowanym procesie redukcji dwutlenku węgla. Z pracy jednoznacznie wynika, że biofilm bakteryjny Y. enterocolitica może być wykorzystany jako aktywna matryca dla rozdrobnionych nanocząstek metali, zdolna do normalizacji ich działania i aktywności elektrokatalitycznej, w tym selektywności, w procesie redukcji CO2. Natomiast w procesie fotoelektrochemicznym zwarta, ale porowata warstwa biofilmu wykazuje zdolność do stabilizacji półprzewodnika Cu2O z zachowaniem jego aktywności katalitycznej.
The main goal of this doctoral dissertation is the utilization of bacterial biofilms to design hybrid bioelectrocatalytic systems capable of reduction of carbon dioxide. The bacteria used in the study is Yersinia enterocolitica (bioserotype 2/O:9), due to its high adaptability and the possibility of survival of this species in diverse ecological niches, and this is the first known attempt to use it in such an inert electrochemical process. The dissertation proposes biocatalytic systems active in electrochemical and photoelectrochemical CO2 conversion processes, containing the biological matrix of Y. enterocolitica and nanoparticles of transition metals or their compounds and complexes, acting as catalytically active centers. Electrochemical reduction of CO2 is an alternative method of converting carbon dioxide into useful chemicals and fuel materials. The CO2 molecule is extremely stable, so its electroreduction is characterized by high reaction overpotentials. Another challenge is the competitive reaction of hydrogen evolution, with a significant impact on the selectivity and dynamics of CO2 reduction. While searching for efficient and selective catalytic systems active in the CO2 electroreduction, metal nanoparticles and their compounds are commonly investigated, but increasingly recognized is also the potential of biological systems: bacterial biofilms. These complex three-dimensional multicellular structures are stable in a wide range of environmental conditions and enable the production of catalytic materials working at normal temperature and under atmospheric pressure. Moreover, their hydrated matrix allows the unimpeded flow of electrolyte ions in the electrocatalytic interface - as a result, biofilms are a kind of ion-conducting hydrogel supporting redox processes. The structure and properties of biofilms make it possible to utilize them as matrices for immobilization of catalytically active molecules in the layer produced by microbes on the electrode surfaces, to stabilize photoelectrochemically active semiconductor materials and to decorate biofilms with various reactive compounds. In the study the influence of the biological matrix on the catalytic activity of different transition metal nanoparticles (Pd, Pt, Ru, PtRu) in the CO2 conversion process is compared. Moreover, a hybrid bioelectrocatalytic system active in the reduction of CO2 is proposed, based on Pt nanoparticles deposited on a biological carrier - Y. enterocolitica biofilm supported by a conductive polymer (polyaniline) and multi-wall carbon nanotubes. A unique method of introducing and dispersing the organometallic ruthenium (II) complex in the biological layer has also been proposed, by modifying the liquid medium for bacterial cultivation with a solution of the desired complex compound (supplementation, "feeding" of bacteria). In addition, a biological matrix is used (along with the Ru (II) complex molecules dispersed in its layer) as a protective coating, stabilizing the unstable p-type semiconductor – copper (I) oxide. The proposed catalytic system present activity in the photoelectrochemical reduction of CO2 and stability under experimental conditions. The doctoral dissertation has concerned: the design of the above-mentioned catalytically active systems assessing their electrocatalytic suit ability, control of the structure of the studied systems, of their stability, of the viability of bacteria in the biological membrane and determination of the role of bacterial biofilm in the analysed process of carbon dioxide reduction. The study clearly shows that Y. enterocolitica biofilm can be used as an active matrix for metal nanoparticles and it is capable of normalizing their performance and electrocatalytic activity, including selectivity, in the CO2 reduction process. Moreover, in the photoelectrochemical process, a compact but porous layer of biofilm shows the ability to stabilize the Cu2O semiconductor while maintaining its catalytic activity.