Dissertations / Theses on the topic 'Nanostructured materials applications'
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1
Kariuki, Nancy N. "Nanostructured materials for electroanalytical applications." Diss., Online access via UMI:, 2005.
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Li, Yanguang. "Nanostructured Materials for Energy Applications." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1275610758.
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Buchholt, Kristina. "Nanostructured materials for gas sensing applications." Doctoral thesis, Linköpings universitet, Tillämpad Fysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-69641.
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In this Thesis I have investigated the use of nanostructured films as sensing and contact layers for field effect gas sensors in order to achieve high sensitivity, selectivity, and long term stability of the devices in corrosive environments at elevated temperatures. Electrochemically synthesized Pd and Au nanoparticles deposited as sensing layers on capacitive field effect devices were found to give a significant response to NOx with small, or no responses to H2, NH3, and C3H6. Pt nanoparticles incorporated in a TiC matrix are catalytically active, but the agglomeration and migration of the Pt particles towards the substrate surface reduces the activity of the sensing layer. Magnetron sputtered epitaxial films from the Ti-Si-C and the Ti-Ge-C systems were grown on 4H-SiC substrates in order to explore their potential as high temperature stable ohmic contact materials to SiC based field effect gas sensors. Ti3SiC2 thin films deposited on 4H-SiC substrates were found to yield ohmic contacts to n-type SiC after a high temperature rapid thermal anneal at 950 ºC. Investigations on the growth mode of Ti3SiC2 thin films with varying Si content on 4H-SiC substrates showed the growth to be lateral step-flow with the propagation of steps with a height as small as half a unit cell. The amount of Si present during deposition leads to differences in surface faceting of the films and Si-supersaturation conditions gives growth of Ti3SiC2 films with the presence of TiSi2 crystallites. Current-voltage measurements of the as-deposited Ti3GeC2 films indicate that this material is also a promising candidate for achieving long term stable contact layers to 4H-SiC for operation at elevated temperatures in corrosive environments. Further investigations into the Ti-Ge-C system showed that the previously unreported solid solutions of (Ti,V)2GeC, (Ti,V)3GeC2 and (Ti,V)4GeC3 can be synthesized, and it was found that the growth of these films is affected by the nature of the substrate.
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Latini, Alessandro. "Inorganic Nanostructured Materials for Technological Applications." Doctoral thesis, La Sapienza, 2006. http://hdl.handle.net/11573/917353.
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Li, Shanghua. "Fabrication of Nanostructured Materials for Energy Applications." Doctoral thesis, Kista : Division of Functional Materials, Department of Microelectronics and Applied Physics, School of Information and Communication Technology, Royal Institute o Technology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4807.
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Fornara, Andrea. "Magnetic nanostructured materials for advanced bio-applications." Licentiate thesis, Stockholm : Informations- och kommunicationsteknik, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9569.
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Bassett, David. "Synthesis and applications of bioinspired inorganic nanostructured materials." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97064.
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Although the study of biominerals may be traced back many centuries, it is only recently that biological principles have been applied to synthetic systems in processes termed "biomimetic" and "bioinspired" to yield materials syntheses that are otherwise not possible and may also reduce the expenditure of energy and/or eliminate toxic byproducts. Many investigators have taken inspiration from interesting and unusual minerals formed by organisms, in a process termed biomineralisation, to tailor the nanostructure of inorganic materials not necessarily found biogenically. However, the fields of nanoparticle synthesis and biomineralisation remain largely separate, and this thesis is an attempt to apply new studies on biomineralisation to nanomaterials science.Principally among the proteins that influence biomineralisation is a group comprised largely of negatively charged aspartic acid residues present in serum. This study is an investigation determining the ability of these serum proteins and other anolagous biomolecules to stabilise biologically relevant amorphous minerals and influence the formation of a variety of materials at the nanoscale. Three different materials were chosen to demonstrate this effect; gold was templated into nanosized single crystals by the action of bioorganic molecules, and the utility of these nanoparticles as a biosensor was explored. The influence of bioorganic molecules on the phase selection and crystal size restriction of titanium dioxide, an important semiconductor with many applications, was explored. The use of bioorganically derived nanoparticles of titanium dioxide was then demonstrated as a highly efficient photocatalyst. Finally, calcium carbonate, a prevalent biomineral was shown to form highly ordered structures over a variety of length scales and different crystalline polymorphs under the influence of a templating protein. In addition, an alternative route to producing calcium phosphate nanoparticle dispersions by mechanical filtration was explored and use as a transfection vector was optimised in two cell lines.Several significant achievements are presented: (i) the assessment of the relative ability of serum, serum derived proteins and their analogues to stabilize the amorphous state, (ii) the formation of single crystalline gold templated by an antibody, (iii) the formation of highly photocatalytically active nanoparticulate anatase by a phosphorylated cyclic esther, (iv) the formation of conical structures at the air liquid interface by the templating ability of a protein and (v) the optimisation of calcium phosphate nanoparticle mediated transfection in two cell lines by mechanical filtration.Malgré le fait que l'étude des biomatériaux remonte à plusieurs siècles, ce n'est que récemment que des principes biologiques furent appliqués à des systèmes synthétiques dans des procédés de "biomimetic" et "bioinspirés", permettant ainsi de nouveaux matériaux de synthèses tout en réduisant l'expansion d'énergie et/ou d'éliminer les résultantes toxiques. Plusieurs chercheurs se sont inspirés des formes inusuelles dès plus intéressantes créées par des organismes, formés par un procédé de biominéralisation, qui modifie la nanostructure des matériaux synthétiques. Toutefois, les champs d'études des synthèses de nanoparticules et de la biominéralisation demeurent grandement à part, et cette thèse tente d'appliquer de nouvelles études de biominéralisation par rapport à la science des nanomatériaux.Les protéines sériques qui influencent la biominéralisation sont chargées négativement de résidus d'aspartate. Cette recherche déterminera l'habileté de ces protéines et des diverses molécules bio–organiques qui stabilisent biologiquement d'important minéraux aux multiples formes qui influencent la formation de matériaux non biogènes sur une nano échelle; l'or et le dioxyde de titane ont permis de démontrer ce résultat. L'or fut transformé en nanoparticules de cristal par l'action des protéines sériques, et c'est l'utilité de ces nanoparticules en tant que biocapteurs qui fut explorée. L'influence des molécules bios-organiques sur le choix de la phase ainsi que sur la restriction de la grosseur du cristal de dioxyde de titane, un important semi-conducteur dans plusieurs applications, fut explorée. Les nanoparticules dérivant bio-organiquement du dioxyde de titane ont dès lors démontrées leur action hautement efficace comme photo catalyseur. Le carbonate de calcium, un biominéral commun, a su démontré sa capacité à auto-former des structures à multiples échelles ainsi que différents polymorphes cristallins sous l'influence d'une protéine modèle. De plus, la manipulation des structures à former divers arrangements est une variable qui fut démontrée. Finalement, la stabilité des nanoparticules du phosphate de calcium à se disperser dans le sérum de culture fut modifiée afin d'optimiser l'efficacité du transfert dans deux lignes de cellules.Plusieurs grandes recherches ont accomplis de façon significative; (i) l'évaluation de l'habileté relative du sérum, le dérivé des protéines sériques et de leur capacité à stabiliser les phases de leurs multiples formes, (ii) la formation simple cristalline de l'or former par un anticorps, (iii) la formation de nanoparticules très actives photocatalytiquement d'anatase formées par un ester cyclique phosphorylée, (iv) la formation de structures coniques à l'interface air liquide par la capacité de gabarits d'une protéine, (iv) l'optimisation de transfection médiation par des nanoparticules de phosphate de calcium dans deux lignées cellulaires par filtration méchanique.
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Renard, Laëtitia. "Nanostructured tin-based materials : sensing and optical applications." Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14183/document.
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Des matériaux hybrides de classe II ont été préparés à partir de précurseurs bis(tripropynylstannylés). Deux familles de précurseurs sol-gel incluant des espaceurs hydrocarbonés et thiophénique ont été obtenues et conduisent à des matériaux hybrides auto-organisés où les plans d’oxyde sont séparés par les espaceurs organiques. Ainsi l’espaceur rigide a donné lieu à une structure pseudo-lamellaire montrant une bande d’émission monomère avec un assez faible décalage vers le rouge par rapport à l'émission des précurseurs en solution. En revanche, alors que les xérogels thiényle plus désordonnés conduisent à une large émission caractéristique de la formation d’excimères ou de dimères. Par ailleurs, des films minces contenant les espaceurs alkylène et arylalkylène ont été préparés et ont montré une morphologie "pseudoparticulaire" poreuse et un ordre à courte distance contenant des réseaux SnOx. De façon inattendue, ces films minces hybrides détectent le dihydrogène dès une température de 50 °C dans la gamme 200-10000 ppm. A partir de ces films hybrides minces, le dioxyde d'étain cristallin (SnO2) a été préparé par un post-traitement thermique. Comme prévu, ces films SnO2 cassitérite détectent le dihydrogène et, dans une moindre mesure le monoxyde de carbone avec une température optimale de fonctionnement comprise entre 300 et 350 °CClass II hybrid materials were prepared from ditin hexaalkynides. Two families of precursors, including either hydrocarbon or oligothiophene-based spacers, were obtained and led by the sol-gel process to self-assembled organotin-based hybrid materials made of planes of oxide separated by organic bridges. Thus, the rigid thienyl spacer gave rise to a “pseudo-lamellar” structure that showed a monomer emission band with a rather small red-shift compared with to the emission of the precursor in solution. However more disordered thienyl xerogels led to broad emission features assigned to excimer or dimer formation. Moreover, thin films containing alkylene- and arylalkylene bridged have been prepared and showed a “pseudoparticulate” porous morphology and a short-range hierarchical order in the organic-inorganic SnOx pseudoparticles. Unexpectedly these hybrid thin films detect hydrogen gas at a temperature as low as 50 °C at the 200-10000 ppm level. From these hybrid thin films, crystalline tin dioxide (SnO2) were prepared by a thermal post-treatment. As expected, cassiterite SnO2 films detected H2 and to a less extent CO with a best operating temperature comprised between 300 and 350 °C
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E, Peisan. "Nanostructured electroactive materials : applications in electroanalysis and electrocatalysis." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/89561/.
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Carbon materials, including single-walled carbon nanotubes (SWNT) and graphene, have gained great interest in electrochemistry. The advantages of carbon electrodes include chemical stability, biocompatibility, low background currents and good electrical conductivity. With the increasing importance of carbon electrode materials for biological and energy application, the systematic investigation and new applications is mandatory. SWNT networks, with different densities, are firstly investigated using microscale capillary electrochemical (EC) methods. Pristine high density (HD) SWNT networks are shown to exhibit more facile electron transfer (ET) for dopamine (DA) electro-oxidation and are less susceptible to blocking by reaction products when compared to low density (LD) SWNT networks. Acid treatment of SWNT networks results in an enhancement of electrode kinetics and a reduction in their susceptibility to surface fouling. Further, a comparison is made between SWNT electrodes, with different densities and a commercial screen printed carbon electrode (SPCE), for the oxidation of ferrocenecarboxylic acid (FcCOOH) in complex aqueous media (polyethylene glycol (PEG) and albumin), to mimic conditions in which diagnostic devices might be used. SWNTs exceed the performance of SPCEs, with a detection limit that is 3 orders of magnitude lower. Finally, a Ni(OH)2 nanoparticles (NPs) modified SWNT network is employed for the methanol oxidation reaction (MOR) and the ethanol oxidation reaction (EOR), showing improved ET processes with ~2.8 kA g-1 for MOR and ~3.7 kA g-1 for EOR, which are much higher than recent reports using other nanostructured catalysts. A fundamental understanding of the structure-activity of “blistered” highly oriented pyrolytic graphite (HOPG), produced by electro-oxidation in HClO4, is obtained using scanning EC cell microscopy (SECCM) coupled with multi-microscopy techniques. The disordered sp2 carbon structure of the blister catalyzes the electro-oxidation of hydrazine compared to the basal surface. In this study, a potential sweep at each pixel of pre-defined scan area is recorded, providing potentiodynamic data with high resolution. To demonstrate that the approaches are generally applicable, a fundamental study of the redox activity for Li2O2 product (toroidal and layer structure) in dimethyl sulfoxide (DMSO) non-aqueous media, is undertaken. A unique gel polymer organic electrolyte (polymer matrix, cross linker and organic electrolyte) is employed in a dual barrel nanopipette and the SECCM approach is carried out with cyclic voltammetry (CV) measurements performed at every pixel of a scan. The Li2O2 toroids outperforms the Li2O2 layer structure with a 9 times increase in the current response and ca. 80 % of charge efficiency. This work provides valuable information with regards to cathode materials for effective Li-air battery.
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RISPLENDI, FRANCESCA. "Nanostructured Materials for Photovoltaic Applications: a Theoretical Study." Doctoral thesis, Politecnico di Torino, 2014. http://hdl.handle.net/11583/2533099.
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We present a theoretical investigation of the main aspects that characterize two novel photovoltaic devices:
the dye sensitized solar cells and all carbon bulk heterojunction cell.
In particular, firstly we studied the
attachment of usually employed anchoring groups and a novel and promising one (squaric acid) to a prototype surface
(rutile-TiO2(110) surface)
to determine the lowest energy adsorption mode and discussing the
electronic properties of the resultant hybrid interface by means of density functional theory (DFT) calculations
using the hybrid exchange (B3LYP) functional.
Secondly, we present a theoretical investigation of the attachment of the hemi-squaraine
dye (CT1) to the anatase-TiO2(101) and ZnO(1-100) surfaces. This molecule can be considered
as prototypical dye for use in dye sensitized solar cells (DSSCs), which present the squaric acid
moiety as anchoring group to determine the lowest energy adsorption
mode and discussing the electronic properties of the resultant hybrid interface by means of
density functional theory (DFT) calculations.
We find that CT1 adsorbs dissociatively at both the TiO2 and ZnO surfaces giving a type II (staggered) heterojunction.
Compared to ZnO surface,
TiO2, due to the greater hybridization of its conduction band states with the unoccupied
molecular orbitals of the dye, is expected to enhance performance when employed with CT1
in DSSCs.
Regarding the all-C BHJ, we analize the relation between stochiometry and the
opto-electronic properties in amorphous carbon and hydrogenated
amorphous carbon thin films to predict their
employment as active layer in innovative photovoltaic devices.
The electronic and optical properties of a large statistical
set of structures are explored by means of firstprinciples
molecular dynamics and electronic structure
calculations, correlating structural features such as the
density, concentration of sp2 and sp3 hybridized C atoms,
and H content to the density of states, Tauc and mobility
gaps, and optical absorption. Our work suggests strategies
to tune and control the bonding geometry and the optical
and electronic properties in amorphous carbon, and
highlights the promising features of this material as valid
substitute to carbon based nanostructured materials.
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STEVANIN, Claudia. "CHARACTERIZATION OF NANOSTRUCTURED ADSORBENT MATERIALS FOR ENVIRONMENTAL APPLICATIONS." Doctoral thesis, Università degli studi di Ferrara, 2022. http://hdl.handle.net/11392/2488253.
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Environmental pollution has grown to become a problem affecting air, water, soil and ecosystems, mainly due to the growth of the world population in combination with rapid economic development, which has led to a massive increase of global production. Indeed, it is linked to the increased use and complexity of chemicals in many human activities. In particular, the global aquatic environment has been affected by widely spread anthropogenic chemicals and, among these, contaminants of emerging interest (CEC), including pharmaceuticals and personal care products, are of particular relevance as they can have a impact on aquatic life and human health. CEC is a term used to describe synthetic or naturally occurring chemicals or any microorganisms that are not commonly monitored in the environment but have the potential to enter the environment and cause known or suspected adverse effects. The main groups of CEC are pharmaceuticals, personal care products, endocrine disruptors, surfactants, persistent organic contaminants, industrial additives and artificial sweeteners. These contaminants are difficult to trace due to the need for specific detection methods, raising the question of how long these contaminants are prevalent in the ecosystem and how the contamination process can be reversed or reduced. Furthermore, several CECs are unlikely to be removed from conventional wastewater treatment (WWT) processes. Advanced wastewater treatment technologies have been identified to be effective in treating contaminated water, such as nanofiltration, reverse osmosis, ozonation and chemical oxidation. Among the different solutions, adsorption, an established technology, is still considered a reliable and robust method to purify aqueous solutions at low cost and with high efficiency. One of the main advantages of adsorption-based technologies is that they are capable of removing contaminants in very low concentration ranges, an operating condition in which most other separation techniques are poorly efficient due to the small concentration gradients involved. . Furthermore, adsorption is a versatile method that can remove many different organic and inorganic compounds at the same time, provided a suitable blend of adsorbent materials is employed.This thesis focused on evaluating different strategies for removing pollutants from the aqueous matrix. In particular, we have studied methods based on adsorption, and in this case we have selected adsorbent materials different from each other in terms of structure, chemical composition and operating conditions, which can be divided into two classes: (i) microporous silica aluminate adsorbent (zeolites) and (ii) carbon-based mixed matrix (MMM) membranes. In this thesis the adsorbing properties of zeolites towards different classes of CEC (drugs, PFAS and organic contaminants) in aqueous solutions were studied in order to study the efficiency of these siliceous materials in two applications, namely: (1) the removal of contaminants from aqueous matrix, (2) the pre-concentration phase for the analysis of micropollutants. Furthermore, the properties of MMM adsorption towards perfluorinated compounds were also investigated. MMMs are composed of a continuous polymeric phase and a dispersed inorganic filler. This thesis includes a study on advanced oxidation processes for the degradation of pharmaceutical products in an aqueous environment. In particular, two different photocatalysts have been studied: (i) sodium decatungstate and (ii) tungsten trioxide, these semiconductors have the common ability to photoproduce .OH radicals in aqueous solutions.L'inquinamento ambientale è cresciuto fino a diventare un problema che colpisce l'aria, l'acqua, il suolo e gli ecosistemi, principalmente a causa della crescita della popolazione mondiale in combinazione con un rapido sviluppo economico, che ha portato a un massiccio aumento della produzione globale. In effetti, è legato all'aumento dell'utilizzo e della complessità delle sostanze chimiche in molte attività umane. In particolare, l'ambiente acquatico globale è stato influenzato da sostanze chimiche antropogeniche ampiamente diffuse e, tra queste, i contaminanti di interesse emergente (CEC), compresi i prodotti farmaceutici e i prodotti per la cura personale, sono di particolare rilevanza poiché possono avere un impatto sulla vita acquatica e salute umana. CEC è un termine usato per descrivere sostanze chimiche sintetiche o presenti in natura o qualsiasi microorganismo che non è comunemente monitorato nell'ambiente ma ha il potenziale di entrare nell'ambiente e causare effetti negativi noti o sospetti. I principali gruppi di CEC sono prodotti farmaceutici, prodotti per la cura personale, interferenti endocrini, tensioattivi, contaminanti organici persistenti, additivi industriali e dolcificanti artificiali. Questi contaminanti sono difficili da rintracciare a causa della necessità di metodi di rilevamento specifici, sollevando la domanda su quanto tempo questi contaminanti siano prevalenti ell'ecosistema e come il processo di contaminazione possa essere invertito o ridotto. Inoltre, è improbabile che diversi CEC vengano rimossi dai processi convenzionali di trattamento delle acque reflue (WWT). Le tecnologie avanzate di trattamento delle acque reflue sono state identificate per essere efficaci nel trattamento delle acque contaminate, come la nanofiltrazione, l'osmosi inversa,l'ozonizzazione e l'ossidazione chimica. Tra le diverse soluzioni, l'adsorbimento, una tecnologia consolidata, è ancora considerata un metodo affidabile e robusto per purificare soluzioni acquose a basso costo e con alta efficienza. Uno dei principali vantaggi delle tecnologie basate sull'adsorbimento è che sono in grado di rimuovere i contaminanti in intervalli di concentrazione molto bassi, una condizione operativa in cui la maggior parte delle altre tecniche di separazione sono scarsamente efficienti a causa dei piccoli gradienti di concentrazione coinvolti. Inoltre, l'adsorbimento è un metodo versatile che può rimuovere contemporaneamente molti diversi composti organici e inorganici, a condizione che venga impiegata una miscela adatta di materiali adsorbenti.Questa tesi si è concentrata sulla valutazione di diverse strategie per rimuovere gli inquinanti dalla matrice acquosa. In particolare, abbiamo studiato metodi basati sull'adsorbimento, e in questo caso sono stati selezionati materiali adsorbenti diversi tra loro per struttura, composizione chimica e condizioni operative, che possono essere suddivisi in due classi: (i) adsorbente microporoso silico alluminato (zeoliti) e (ii) membrane a matrice mista a base di carbonio (MMM). In questa tesi sono state studiate le proprietà adsorbenti delle zeoliti verso diverse classi di CEC (farmaci, PFAS e contaminanti organici) in soluzioni acquose al fine di studiare l'efficienza di questi materiali silicei in due applicazioni, ovvero: (1) la rimozione di contaminanti da matrice acquosa, (2) la fase di pre-concentrazione per l'analisi dei microinquinanti. Inoltre, sono state studiate anche le proprietà di adsorbimento MMM verso i composti perfluorurati. Le MMM sono composti da una fase polimerica continua e da una carica inorganica dispersa. Questa tesi include uno studio sui processi di ossidazione avanzati per la degradazione di prodotti farmaceutici in ambiente acquoso. In particolare sono stati studiati due diversi fotocatalizzatori: (i) decatungstato di sodio e (ii) triossido di tungsteno, questi semiconduttori hanno la capacità comune di fotoprodurre radicali .OH in soluzioni acquose.
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MONAI, MATTEO. "NANOSTRUCTURED MATERIALS FOR ENVIRONMENTAL AND ENERGY-RELATED APPLICATIONS." Doctoral thesis, Università degli Studi di Trieste, 2017. http://hdl.handle.net/11368/2908133.
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The world is facing an era of global environmental pollution, as a result of the tremendous population growth and the consequent massive fossil fuel-based energy consumption. A significant exploitation of renewable energies is needed to guarantee quality of human life and allow further sustainable growth, but this may take decades to happen. In order to mitigate the negative effect of human activities on the environment in the short- and mid-term, the development of more efficient technologies for emissions abatement and for renewable fuels production is imperative. Heterogeneous catalysis and photocatalysis are two key pillars of a multi-approach strategy to solve these issues.
During the last century, catalysts were explored by changing the formulation of multi-component systems in order to find the best performing material for a certain reaction. Since the late 90's, a new approach to catalytic systems improvement emerged: nano-catalysis. Exploiting the tools of nanotechnology, tailored nanostructured materials can now be produced, which show different properties in comparison to their bulky counterparts, often resulting in better catalytic performances. Furthermore, combining the elements of the periodic table in nano-alloys allows to expand the possibility of catalyst generation. Consistently with these approaches, the main focus of this thesis is the synthesis and characterization of well-defined nanostructured and hierarchical materials for environmental and energy-related applications, such as emissions control, biofuels synthesis and photocatalytic H2 production. We show that structural control at the nanoscale is a great instrument for understanding reaction pathways, for studying the nature of catalytic active sites, and for synthesizing more selective, active and stable catalysts.
Two synthetic strategies were followed to acquire nanostructural control: a self-assembly method was employed to prepare hierarchical materials starting from functional nanoparticles, and advanced solvothermal methods were used to prepare monodisperse nanocrystals having controlled size and composition. State-of-the-art hierarchical Pd-based catalysts embedded by metal oxide promoters were tested for methane catalytic oxidation in the presence of poisoning compounds typically found in real applications. Detailed surface studies allowed to propose deactivation mechanisms and strategies to improve catalysts resistance to deactivation. Well-controlled nanostructured Pt-based alloys and Ni-Cu alloys showed improved activity, stability and selectivity for hydrodeoxygenation reactions of biomass-derived feedstocks to produce biofuels. The control of nanostructure was pivotal to understand the reason for such enhanced performances. Finally, dye-sensitized photocatalysts were investigated in H2 photocatalytic production under visible light, and state-of-the-art stability and activities were demonstrated.
All these findings greatly contributed to the development of catalytic materials for energy-related applications.
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Mavundla, Sipho Enos. "One-Dimensional nanostructured polymeric materials for solar cell applications." Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_1088_1305888911.
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This work entails the preparation of various polyanilines with different morphologies and their application in photovoltaic solar cells. Zinc oxide (ZnO) with one-dimensional and flower-like morphology was also prepared by microwave irradiation and used as electron acceptors in photovoltaics devices. The morphological, structural, spectroscopic and electrochemical characteristics of these materials were determined by scanning electron microscopy (SEM), X-Ray diffraction (XRD), Raman, Fourier-transformed infrared spectroscopy (FTIR), ultraviolet and visible spectroscopy (UV-Vis), photoluminescence(PL), thermal gravimetric analysis (TGA) and cyclic voltammetry (CV) experiments. Devices fabricated from these materials were characterized under simulated AM 1.5 at 800 mW.
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Skvortsova, Yulia Alexandrovna Geng M. Lei. "Simulation of tissues for biomedical applications." [Iowa City, Iowa] : University of Iowa, 2009. http://ir.uiowa.edu/etd/436.
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Tang, Shijun Hu Zhibing. "Characterization, properties and applications of novel nanostructured hydrogels." [Denton, Tex.] : University of North Texas, 2006. http://digital.library.unt.edu/permalink/meta-dc-5605.
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Ye, Fei. "Synthesis of nanostructured and hierarchical materials for bio-applications." Licentiate thesis, KTH, Funktionella material, FNM, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-35518.
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In recent years, nanostructured materials incorporated with inorganic particles and polymers have attracted attention for simultaneous multifunctional biomedical applications. This thesis summarized three works, which are preparation of mesoporous silica coated superparamagnetic iron oxide (Fe3O4@mSiO2) nanoparticles (NPs) as magnetic resonance imaging T2 contrast agents, polymer grafted Fe3O4@mSiO2 NPs response to temperature change, synthesis and biocompatibility evaluation of high aspect ratio (AR) gold nanorods. Monodisperse Fe3O4@mSiO2 NPs have been prepared through a sol-gel process. The coating thickness and particle sizes can be precisely controlled by varying the synthesis parameters. Impact of surface coatings on magnetometric and relaxometric properties of Fe3O4 NPs is studied. The efficiency of these contrast agents, evaluated by MR relaxivities ratio (r2/r1), is much higher than that of the commercial ones. This coating-thickness dependent relaxation behavior is explained due to the effects of mSiO2 coatings on water exclusion. Multifunctional core-shell composite NPs have been developed by growing thermo-sensitive poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAAm-co-AAm)) on Fe3O4@mSiO2 NPs through free radical polymerization. Their phase transition behavior is studied, and their lower critical solution temperature (LCST) can be subtly tuned from ca. 34 to ca. 42 °C, suitable for further in vivo applications. A seedless surfactant-mediated protocol has been applied for synthesis of high AR gold nanorods with the additive of HNO3. A growth mechanism based on the effect of nitrate ions on surfactant micelle elongation and Ostwald ripening process is proposed. The biocompatibility of high AR nanorods was evaluated on primary human monocyte derived dendritic cells (MDDCs). Their minor effects on viability and immune regulatory markers support further development for medical applications.QC 20110701
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Carrara, Serena. "Towards new efficient nanostructured hybrid materials for ECL applications." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF016/document.
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Cette thèse vise à développer de nouveaux matériaux hybrides pour les applications en électrochimiluminescence. Les propriétés électrochimiluminescentes de nouveaux complexes de Pt(II) et d’Ir(III) ont été explorés comme alternative aux marqueurs existants. En plus, la combinaison de complexes et de carbon nanodots portant des groupes primaires ou tertiaires à la surface comme espèces coréactives a abouti à une stratégie intéressante pour éliminer la TPrA. Les carbon nanodots dans un systéme lié par liaison covantent avec complexes métalliques sont non seulement un support innocent pour les espèces actives d’ECL, mais agissent également comme coréactif, se révélant être une plateforme auto-améliorante en ECL. Enfin, un véritable immunoessai pour la détection des marqueurs cardiaques a été mis au point avec une sensibilité et une stabilité accrues pour les applications de détection biologique et biomédicale. La même technologie peut alors être appliquée à une variété d’autres analytes, ouvrant ainsi le site à d’autres dosagesThis doctoral dissertation aim to develop new hybrid materials for ECL applications. In the field of metal complexes, the electrochemiluminescent properties of new Pt(II) and Ir(III) complexes were investigated as alternative of existing complexes. Passing to nanomaterials, the combination of labels and NCNDs bearing primary or tertiary groups on the surface as alternative co-reactant species resulted an interesting strategy to eliminate the toxic TPrA. In particular, NCNDs in covalently linked system with metal complexes is not only an innocent carrier for ECL active species, but act also as co-reactant in the ECL process, revealing itself an ECL self-enhancing platform. Finally, a real immunoassay for cardiac marker detection has been built with enhanced sensitivity and stability, which is of fundamental importance for biological and bio-medical detection applications. The same technology can be applied to a variety of other analytes opening the venue to other assays
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Quintero-Jaime, Andrés Felipe. "Electrochemical Functionalization of Nanostructured Carbon Materials for Bioelectrochemical Applications." Doctoral thesis, Universidad de Alicante, 2020. http://hdl.handle.net/10045/116499.
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Esta tesis doctoral se centra en el desarrollo de diferentes métodos electroquímicos y químicos para la funcionalización de materiales de carbono nanoestructurados, obteniendo materiales electródicos funcionales para aplicaciones bioelectroquímicas. En este sentido, las propiedades en superficie influyen directamente en la interacción entre el elemento bioreceptor o biocatalizador con el electrodo. Por tal motivo, se puede mejorar la cinética de transferencia de electrones, la inmovilización, orientación y distribución del bioelemento en el electrodo, mejorando el rendimiento del dispositivo bioelectroquímico, a partir de la química superficial del material empleado. El uso de diferentes funcionalidades de nitrógeno y fósforo generados electroquímicamente sobre los materiales de carbono nanoestructurados proporciona una plataforma para la síntesis controlada, para mejorar la actividad catalítica de biocatalizadores. Además, el proceso electroquímico de funcionalización ha demostrado ser una ruta interesante para preparar bioelectrodos en un solo paso, con bajo consumo de elementos enzimáticos y un rendimiento sobresaliente a los métodos convencionales actuales. Por otro lado, el uso de materiales de carbono dopados en N cuaternarios como elemento transductor en la síntesis de un biosensor enzimático de glucosa libre de metales proporciona, en condiciones aeróbicas, un biosensor de alta sensibilidad para la detección de glucosa en orina y bebidas azucaradas comerciales, con bajo efecto de los interferentes y alta estabilidad. Finalmente, la modificación de los nanotubos de carbono con nanopartículas de oro proporciona un material de electrodo transductor escalable y estable en el que tiene lugar la inmovilización de anticuerpos a través de interacciones Au-8. La formación de antígeno-anticuerpo complejo provoca efectos estéricos que producen un impedimento para la transferencia de electrones proveniente de una sonda redox activa hacia la superficie del electrodo, lo que facilita la detección del analito.
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Zhang, Yi. "Physical properties investigation of nanostructured materials and their applications /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2007. http://uclibs.org/PID/11984.
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Cho, Joungmo. "Computational studies of reacting flows with applications in nanoscale materials synthesis." Amherst, Mass. : University of Massachusetts Amherst, 2009. http://scholarworks.umass.edu/dissertations/AAI3372259/.
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Wang, Ling. "Syntheses and applications of bisphosphonate-based biomaterials and nanomaterials /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202007%20WANG.
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Nyoni, Stephen. "Nanocomposites of carbon nanomaterials and metallophthalocyanines : applications towards electrocatalysis." Thesis, Rhodes University, 2016. http://hdl.handle.net/10962/d1020846.
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Nanohybrid materials have been prepared and examined for their electrocatalytic activity. The nanocomposites have been prepared from carbon nanomaterials (multiwalled carbon nanotubes (MWCNTs) and graphene nanosheets), cadmium selenide quantum dots and metallophthalocyanines (MPcs). The MPcs used in this work are cobalt tetraamino-phthalocyanine (CoTAPc) and tetra (4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninatocobalt (II)) (CoPyPc). Their activity has also been explored in different forms; polymeric MPcs, iodine doped MPcs and covalently linked MPcs. The premixed drop-dry, sequential drop-dry and electropolymerisation electrode modification techniques were used to prepare nanocomposite catalysts on the glassy carbon electrode (GCE) surface. The sequential drop dry technique for MPc and MWCNTs gave better catalytic responses in terms of limit of detection, catalytic and electron transfer rate constants relative to the premixed. MWCNTs and CdSe-QDs have been used as intercalating agents to reduce restacking of graphene nanosheets during nanocomposite preparation. Voltammetry, chronoamperometry, scanning electrochemical microscopy and electrochemical impedance spectroscopy methods are used for electrochemical characterization modified GCE. X-ray photoelectron spectroscopy, X-ray diffractometry, transmission electron microscopy, scanning electron microscopy, infra-red spectroscopy, Raman spectroscopy were used to explore surface functionalities, morphology and topography of the nanocomposites. Electrocatalytic activity and possible applications of the modified electrodes were tested using oxygen reduction reaction, l-cysteine oxidation and paraquat reduction. Activity of nanocomposites was found superior over individual nanomaterials in these applications.
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Fang, Liming. "Processing of UHMWPE and HA/UHMWPE nanocomposite for biomedical applications /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?MECH%202006%20FANG.
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Cao, Shuai. "Nanostructured metal-organic frameworks and their amorphization, carbonization and applications." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.707948.
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Yar, Mazher Ahmed. "Development of Nanostructured Tungsten Based Composites for Energy Applications." Doctoral thesis, KTH, Funktionella material, FNM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-101319.
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Tungsten (W) based materials can be used in fusion reactors due to several advantages. Different fabrication routes can be applied to develop tungsten materials with intended microstructure and properties for specific application including nanostructured grades. Therein, innovative chemical routes are unique in their approach owing numerous benefits. This thesis summarizes the development of W-based composites dispersed-strengthened by rare earth (RE) oxides and their evaluation for potential application as plasma facing armour material to be used in fusion reactor. Final material development was carried out in two steps; a) fabrication of nanostructured metallic tungsten powder dispersed with RE-oxides and b) powder sintering into bulk oxide-dispersed strengthened (ODS) composite by spark plasma process. With the help of advanced characterization tools applied at intermediate and final stages of the material development, powder fabrication and sintering conditions were optimized. The aim was to achieve a final material with a homogenous fine microstructure and improved properties, which can withstand under extreme conditions of high temperature plasma. Two groups of starting materials, synthesized via novel chemical methods, having different compositions were investigated. In the first group, APT-based powders doped with La or Y elements in similar ways, had identical particles’ morphology (up to 70 μm). The powders were processed into nanostructured composite powders under different reducing conditions and were characterized to investigate the effects on powder morphology and composition. The properties of sintered tungsten materials were improved with dispersion of La2O3 and Y2O3 in the respective order. The oxide dispersion was less homogeneous due to the fact that La or Y was not doped into APT particles. The second group, Ydoped tungstic acid-based powders synthesized through entirely different chemistry, contained nanocrystalline particles and highly uniform morphology. Hydrogen reduction of doped-tungstic acid compounds is complex, affecting the morphology and composition of the final powder. Hence, processing conditions are presented here which enable the separation of Y2O3 phase from Y-doped tungstic acid. Nevertheless, the oxide dispersion reduces the sinterability of tungsten powders, the fabricated nanostructured W-Y2O3 powders were sinterable into ultrafine ODS composites at temperatures as low as 1100 °C with highly homogeneous nano-oxide dispersion at W grain boundaries as well as inside the grain. The SPS parameters were investigated to achieve higher density with optimum finer microstructure and higher hardness. The elastic and fracture properties of the developed ODS-W have been investigated by micro-mechanical testing to estimate the materials’ mechanical response with respect to varying density and grain size. In contrast from some literature results, coarse grained ODS-W material demonstrated better properties. The developed ODS material with 1.2 Y2O3 dispersion were finally subjected to high heat flux tests in the electron beam facility “JUDITH-1”. The samples were loaded under ELM-like thermal-shocks at varying base temperatures up to an absorbed power density of 1.13 GW/m2, for armour material evaluation. Post mortem characterizations and comparison with other reference W grades, suggest lowering the oxide contents below 0.3 wt. % Y2O3. As an overview of the study conducted, it can be concluded that innovative chemical routes can be potential replacement to produce tungsten based materials of various composition and microstructure, for fusion reactor applications. The methods being cheap and reproducible, are also easy to handle for large production at industrial scale.QC 20120827
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Abdelaaziz, Muftah Ali. "Synthesis of nanocomposites with nano-TiO2 particles and their applications as dental materials." Thesis, Cape Peninsula University of Technology, 2012. http://hdl.handle.net/20.500.11838/1534.
Full textAbstract:
Thesis submitted in fulfilment of the requirements for the degree
Magister of Technology: Dental Technology
In the Faculty of Health and Wellness Sciences
At the Cape Peninsula University of Technology, 2012A study of the modification of dental nanocomposites with nanosized fillers is presented. The incorporation of TiO2 (titania) nanoparticles, via a silane chemical bond, to a standard dental acrylic resin matrix was explored to determine whether there was an increase in the wear resistance, flexural strength and surface hardness properties of the dental nanocomposites. The principal aim of this study was to synthesize dental nanocomposites with different sizes, treated, nano-TiO2 fillers in urethane dimethacrylate (UDMA) for potential application in posterior restoration and to evaluate their mechanical properties. Treatment of the nano-TiO2 particles was carried out with a silane coupling agent, 3-(methacryloyloxy)propyltrimethoxysilane (MPTMS), to improve bonding between the nano-TiO2 particles and acrylic matrix (UDMA), and reduce agglomeration of the nano-TiO2. Characterisation of products was carried out using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fourier transform infrared spectroscopy (FTIR). TEM results were used to compare the particle size distributions of untreated TiO2 and treated TiO2 under various experimental conditions in an ethanol solvent, while SEM images showed the adhesion between the matrix (UDMA) and the nano-TiO2. FTIR was used to show the qualitative composition of untreated TiO2 and treated TiO2. Eighteen groups of experimental dental nanocomposites were evaluated. Each group contained different average particle sizes of nano-TiO2 (filler): 5 nm, 21 nm and 80 nm. Each particle size category was treated with three different concentrations of the silane, (MPTMS): 2.5, 10 and 30 wt %. Samples were prepared by mixing the monomer resin matrix of UDMA and nano-TiO2 particles. For comparison, a commercially available dental resin was reinforced with untreated and treated nano-TiO2 particle sizes 5, 21 and 80 nm. Wear resistance, flexural strength and surface hardness of TiO2 nanocomposites treated with 2.5 wt % MPTMS were significantly higher compared to those treated with 10 and 30 wt% MPTMS. The nanocomposites with 5 nm TiO2 had higher wear loss, lower flexural strength and lower surface hardness values compared to those with 21 nm and 80 nm TiO2. Statistical analysis showed that the effect of the concentrations of MPTMS on wear resistance and surface hardness of specimens was significant (p<0.001), which is less than 0.05, while the effect of the concentration of MPTMS on flexural strength was statistically not significant, (p=0.02). Control composites reinforced with treated 80 nm TiO2 particles had much better mechanical properties than any of the other specimens. It was concluded that the most available commercial product for dental restorations could be improved by the addition of nano-TiO2 with relatively large particle size.
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Tang, Shijun. "Characterization, Properties and Applications of Novel Nanostructured Hydrogels." Thesis, University of North Texas, 2006. https://digital.library.unt.edu/ark:/67531/metadc5605/.
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The characterization, properties and applications of the novel nanostructured microgel (nanoparticle network and microgel crystal) composed of poly-N-isopropylacrylanmide-co-allylamine (PNIPAM-co-allylamine) and PNIPAM-co-acrylic acid(AA) have been investigated. For the novel nanostructured hydrogels with the two levels of structure: the primary network inside each individual particle and the secondary network of the crosslinked nanoparticles, the new shear modulus, drug release law from hydrogel with heterogeneous structure have been studied. The successful method for calculating the volume fraction related the phase transition of colloid have been obtained. The kinetics of crystallization in an aqueous dispersion of PNIPAM particles has been explored using UV-visible transmission spectroscopy. This dissertation also includes the initial research on the melting behavior of colloidal crystals composed of PNIPAM microgels. Many new findings in this study area have never been reported before. The theoretical model for the columnar crystal growth from the top to bottom of PNIPAM microgel has been built, which explains the growth mechanism of the novel columnar hydrogel colloidal crystals. Since the unique structure of the novel nanostructured hydrogels, their properties are different with the conventional hydrogels and the hard-sphere-like system. The studies and results in this dissertation have the important significant for theoretical study and valuable application of these novel nanostructured hydrogels.
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Chen, Fanglin. "Synthesis and characterization of nanostructured materials for electrochemical and catalytic applications." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/20004.
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García, Torres José Manuel. "Electrochemical Preparation of Co-Ag Nanostructured Materials for GMR Applications." Doctoral thesis, Universitat de Barcelona, 2010. http://hdl.handle.net/10803/2763.
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The electrodeposition is a technique that day by day is gaining positions among the mainly employed physical methods. This is due to the fact that electrodeposition shows some advantages over the physical techniques such as: versatility, selectivity, room temperature, high deposition rates, high thicknesses, among others. Therefore, the aim of this thesis is the use of the electrochemical technology to prepare Co-Ag nanostructured materials for magntoresistive applications.The first step was the preparation of granular films. However, the big difference in the standard potentials of both metals discards their codeposition and therefore, the main problem to overcome was to reduce this difference. Different electrolytic baths containing different complexing agents (Bath 1: Thiourea, bath 2: Thiosulphate and bath 3: Chloride) were employed in order to favour the codeposition. After optimizing the composition of each solution, Co-Ag films with a distribution of nanometric cobalt particles into the silver matrix were obtained. However, the deposits prepared from baths 1 and 2 only showed giant magnetoresistnace (GMR) at low temperatures, fact that was attributed to the presence of sulphur in the magnetic/non-magnetic interfaces which hindered the magnetoresistance effect to take place. The use of a sulphur-free bath (bath 3) allowed obtaining films with GMR values up to 7% at room temperature, values higher than those published by others. The numerical analysis of the magnetoresistance curves, which allowed the decomposition of the magnetoresistance curves into its ferromagnetic (FM) and superparamagnetic (SPM) contribution, indicated the higher SPM contribution over the FM one in all the electrodeposition conditions.
On the other hand and taking profit of the versatility of the electrodeposition, Co-Ag multilayers were prepared. The magnetic (Co) and non-magnetic (Ag) layer deposition condition optimization was crucial to obtain the highest GMR values.
The electrochemical technology was also useful to prepara Co-Ag nanowires (both granular and multilayered nanowires) into the pores of polycarbonate membranes. Moreover, nanoparticles of the Co-Ag system were also prepared with a core-shell structure and by the microemulsion method. A voltammetric method was developed to univocally determine the correct core-shell structure formation. An strategy was also developed to measure the magnetoresistance of the last two kinds of nanomaterials (nanowires and nanoparticles) which corroborated their magnetoresistive behaviour.
L'electrodeposició és una tècnica que, dia rere dia, escala posicions entre les més habitualment emprades tècniques físiques de deposició. Aquest fet es deu principalment als avantatges que presenta la tècnica electroquímica front als mètodes físics, essent aquests: versatilitat, selectivitat, equipament senzill, temperatura ambient, elevades velocitats de deposició, gruixos importants,..Aquest projecte de tesi desenvolupa la preparació electroquímica de materials nanoestructurats cobalt-plata, material que potencialment és útil en aplicacions magnetorresistives.
El nostre objectiu inicial va ser la preparació de pel·lícules granulars. El primer problema que va haver de superar-se per aconseguir la codeposició d'ambdós metalls va ser reduir l'elevada diferència entre els seus potencials de deposició. Es van utilitzar diferents banys electrolítics contenint agents complexants (bany 1:Tiourea, bany 2: Tiosulfat i bany 3: Clorurs) per tal d'afavorir la codeposició, Les formulacions optimitzades d'aquests banys van permetre aconseguir dipòsits amb una dispersió de partícules nanomètriques de cobalt a la matriu de plata. No obstant això els dipòsits preparats a partir dels banys 1 i 2 únicament presentaren magnetorresistència gegant a temperatures criogèniques, fet que es va relacionar amb la presència de sofre a les interfases magnètiques/no magnètiques, proposta que es va confirmar posteriorment.
Afortunadament el bany base-clorurs (bany 3) va permetre obtenir dipòsits amb valors de GMR de fins a un 7% a temperatura ambient, valors sensiblement superiors als trobats a la literatura. Un tractament de les dades experimentals amb un model teòric va permetre establir la contribució a la magnetoresistència de les partícules de cobalt d'acord amb la seva mida.
D'altre banda aprofitant la versatilitat de l'electrodeposició, es va procedir a la preparació de multicapes Co-Ag. L'optimització de les condicions d'electrodeposició tant de la capa magnètica (Co) com de la capa no magnètica (Ag) va ser decisiva per tal d'obtenir estructures amb GMR.
El mètode electroquímic va ser útil per obtenir fils de mida nanomètrica de Co-Ag a partir de templates de membranes de policarbonat, tant granulars com en forma de multicapa. D'aquest material, Co-Ag, s'han preparat nanoparticules amb estructura nucli-corona pel mètode de la microemulsió, per les que s'ha desenvolupat un mètode electroquímic de caracterització que ha permès comprovar la correcta formació de les nanoparticles. Per la mesura de GMR d'aquests sistemes nanomètrics (nanofils i nanoparticles) s'ha dissenyat un procediment experimental de mesura que ha confirmat el caràcter magnetoresistiu de les nanoestructures.
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Patel, Alpa C. Wei Yen. "Bioapplicable, nanostructured and nanocomposite materials for catalytic and biosensor applications /." Philadelphia, Pa. : Drexel University, 2006. http://hdl.handle.net/1860/1124.
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Lowe, John Beresford. "Novel preparative routes to nanostructured materials for fuel cell applications." Thesis, University of St Andrews, 2014. http://hdl.handle.net/10023/11949.
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Nanostructured materials with high specific surface areas and high pore volumes are of interest for applications in solid oxide fuel cells (SOFCs). This study describes the use of novel preparative methods for obtaining nanostructured samarium-doped ceria (SDC) with a view to its application as an anode material in SOFCs. The strategy employed in this work was based on the nanocasting concept. Template materials with a polymer, carbon or silica framework are first obtained using a self-assembly process. These materials have long range networks of ordered mesopore channels and so act as templating moulds. From a three step procedure of precursor impregnation, in-situ formation of SDC by calcination and template removal, SDC with the inverse pore structure of the template is created. Novel methods for producing such SDC materials were applied and the products evaluated. As silica templates have wide ranging applications involving exposure to high temperatures -not least in nanocasting- it was desirable to understand the thermal stability of these materials over a range of temperatures. A systematic study was conducted on three representative silica templates. An inherent problem in nanocasting from silica templates is retention of residual silica after the template removal step. A detailed investigation into these alternative wet chemistry procedures was undertaken. To circumvent the silica problem completely, a number of alternative templates made of mesoporous carbon were considered. A range of ordered mesoporous carbons were prepared and evaluated as templates. To provide a comparator for the ordered SDC materials, a simple combustion method was used to prepare an SDC product without the influence of a structure directing template. The techniques of TEM, SEM-EDX, UV–Vis spectroscopy, MAS-NMR, PXRD and gas physisorption were used to characterise the physical and chemical properties of the products in the bulk and at the nanoscale.
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Shen-Ming, Chen. "Applications of nanostructured materials and biomolecules for electrocatalysis and biosensors." Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20454.
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Electronically conducting polymers are important materials, and composites of
these materials with metal nanoparticles have also been drawn significant research attention
in recent years. We prepared a highly stable Agnano-Poly (3, 4-ethylenedioxythiophene) (PEDOT) nanocomposite by one-pot synthesis method. Here,
3, 4-ethylenedioxythiophene (EDOT) is used as the reductant and polystyrene sulfonate
(PSS-) as a dopant for PEDOT as well as particle stabilizer for silver nanoparticles
(AgNPs). Agnano–PEDOT/PSS-nanocomposite was characterized by infrared (IR) spectroscopy,
transmission electron microscopy (TEM). AgNPs are distributed uniformly
around PEDOT polymer with an average particle size diameter of 10–15 nm and the
nanocomposite film showed catalytic activity towards 4-nitro phenol. Some types of
including Ag bimetallic nanoparticles and nanostructured materials could be directly
applied for the electroanalysis and biosensing applications.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/20454
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Gallagher, Jamie Brian. "Synthesis of nanostructured materials with potential renewable energy generation applications." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/7040/.
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The work in this thesis is concerned with growth of low dimensional materials in a variety of morphologies which have potential renewable energy generation applications. The work described within demonstrates synthesis methods for the production of materials with thermoelectric applications and materials for photovoltaic purposes. Products are characterised using a range of techniques including: scanning and transmission electron microscopy; energy dispersive X-ray spectroscopy and powder X-ray diffraction. Presented here is an investigation into the growth of bismuth telluride on silicon surfaces via chemical vapour deposition (CVD). Resultant particle morphology is reported in relation to experimental conditions such as surface conditions (silicon, gold/palladium on silicon and disordered silicon surfaces), temperature and reagent concentration. Successful synthesis of Bi2Te3 plates is presented starting from elemental precursors via a closed vessel CVD process. Plates with sub-micron thickness (but up to 40 μm diameter) are produced template free on a silicon surface and without the need for transport gases or expensive precursors. Using modification of silicon surfaces the growth of 2-4 μm tetragonal pyramids of Bi2Te3 are demonstrated. CVD is also used to produce bismuth rich nanowires up to 40 μm but <100 nm in diameter, these were produced by increasing the bismuth concentration in comparison to other methods. This thesis also details an investigation into the suitability of a range of substrates for CVD. Alumina is demonstrated to be a suitable surface for Bi2Te3 CVD with nanostructured Bi2Te3 spheres of 5-20 μm diameter presented. Additionally vertically aligned arrays of copper telluride are presented using a single step CVD process. Arrays consist of hexagonal plates <500 nm in thickness but up to 25 μm in diameter. Due to preferential reaction with tellurium GaAs is demonstrated to be a poor facilitator for Bi2Te3 growth as is cobalt. The production of nanostructured sphere of TiO2 is also presented. Spheres with tuneable diameter are produced in <60 s in multi-mode microwave reactors using a hydrothermal process. The spheres are comprised of radially aligned nanorods producing spheres of 1-3 μm. Spheres are demonstrated to be a single rutile TiO2 phase. Spheres are characterised with phase, band gap and morphology presented and influence of experimental parameters such as time and reagent concentration is discussed. 2 Finally this work investigates the doping and conversion of TiO2 structures to TiN and TiO2-xNx structures. Using ammonolysis TiO2 is converted to a TiN structure while retaining its original its original spherical morphology. Using the same ammonolysis process TiO2 is doped and the demonstrational shift in band gap to the visible region is presented.
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Schiavo, Loredana. "Synthesis and Characterization of Nanostructured Materials for Hydrogen Storage Applications." Doctoral thesis, Università degli studi di Trento, 2017. https://hdl.handle.net/11572/368885.
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The development of new materials represents the recent frontier in hydrogen storage technologies. In the last few decades the preparation of nanostructured materials has had an increasing interest, because the hydrogen storage capacity is closely linked to the material dimensions, and increases considerably with the reduction of the particles sizes. The chemical synthesis plays an important role in the development of new materials for hydrogen absorption because it allows a good control of the hydride phase sizing, and thus of the kinetics/ thermodynamics of such materials. The aim of the work concerns the synthesis by chemical techniques of metals nanoparticles. Nanostractured metals embedded into a polymeric matrix are prepared. The polymer was used for achieving nanoparticles with tailored properties.
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Schiavo, Loredana. "Synthesis and Characterization of Nanostructured Materials for Hydrogen Storage Applications." Doctoral thesis, University of Trento, 2017. http://eprints-phd.biblio.unitn.it/2682/1/Deposit_Disclaimer_Loredana_Schiavo.pdf.
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The development of new materials represents the recent frontier in hydrogen storage technologies. In the last few decades the preparation of nanostructured materials has had an increasing interest, because the hydrogen storage capacity is closely linked to the material dimensions, and increases considerably with the reduction of the particles sizes. The chemical synthesis plays an important role in the development of new materials for hydrogen absorption because it allows a good control of the hydride phase sizing, and thus of the kinetics/ thermodynamics of such materials. The aim of the work concerns the synthesis by chemical techniques of metals nanoparticles. Nanostractured metals embedded into a polymeric matrix are prepared. The polymer was used for achieving nanoparticles with tailored properties.
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杨纯臻 and Chunzhen Yang. "Metal/metal oxide nanoparticles supported on nanostructured carbons for electrochemical applications." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/193414.
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Among various electrochemical devices that have been developed for energy storage and conversion, electric double layer capacitors (EDLCs) and direct methanol fuel cells (DMFC) have received much research attention. Nanostructured carbon materials have been playing an important role in the development of these devices, due to such characteristics as good electrical conductivity, high chemical stability, high surface area and large pore volumes and etc. In an EDLC, nanostructured carbon electrodes, possessing pores of varied length scales, can deliver electric energy at high current loadings. This kind of pore structure also benefits the deposition of metal catalysts and the transport of reactants and products in the methanol oxidation reaction.
In order to systematically study the structural effects on the electrochemical capacitance and ionic transport, a series of three-dimensional hierarchical carbons with hollow core-mesoporous shell (HCMS) structure were template-synthesized. Periodically ordered macroscopic hollow cores of 330 nm in diameter were surrounded by a mesoporous shell containing uniform pores of 3.9 nm. The shell thickness was stepwise increased from 0, 25, 50 to 100 nm. The HCMS structure was modeled by a 5-level transmission line model to study the capacitance contribution from the pores at different length scale. Results revealed that the HCMS carbon with thicker mesoporous shells can provide high capacitance, while thinner shells could deliver high power output.
A series of HCMS carbon sphere supported Pt nanoparticles were synthesized via the “Carbonization over Protected and Dispersed Metal” (CPDM) method. Contrary to the conventional “polyol” synthetic method, whereas most of Pt nanoparticles were deposited on the external surface of carbon spheres; the Pt nanoparticles synthesized via the CPDM method were found encapsulated in the mesoporous carbon shells and highly dispersed throughout the carbon texture. „Accelerated stress tests‟ (ASTs) were conducted to investigate the nanopores confinement effect toward the electrochemical stability of these Pt catalysts. Results revealed that (1) the nanopores confined Pt nanoparticles on HCMS carbon spheres exhibited a stable electrochemical active surface area (ECSA) and catalytic activity; and (2) thick mesoporous carbon shells could provide better protection over the Pt nanoparticles. This “CPDM” method was further extended to synthesize highly alloyed PtRu nanoparticles supported electrocatalysts. It is expected that this CPDM method can also be applied to synthesize other metal/metal oxide supported catalysts with stable electrochemical performance.
WO3 has been demonstrated as a promsing co-catalyst for Pt in the methanol oxidation reaction (MOR). The synthesis of Pt-WO3/C catalyst with well-controlled nanoparticle size (2.5 nm) and composition was achieved via a microwave-assisted water-oil microemulsion reaction. Hydrogen adsorption, CO-stripping and Cu- stripping methods were used to estimate the ECSA of Pt in the Pt-WO3/C catalysts. Among these, Cu-stripping method was relatively more reliable due to the overlapping involvement of the WO3 component in the other methods. The methanol oxidation measurement shows that a 1:1 Pt:W ratio catalyst exhibits the highest Pt-mass current density of 271 mA mg-1-Pt, 1.4 times higher than that of commercial E-TEK catalyst.published_or_final_version
Chemistry
Doctoral
Doctor of Philosophy
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ANDREOZZI, ANDREA. "Fabrication of nanostructured materials using block copolymer based lithography." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2012. http://hdl.handle.net/10281/28333.
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The main objective of the PhD research activity carried out at MDM Laboratory was the growth and manipulation of nano-objects to be used as building blocks for the fabrication of new generation of nano-transistors, nano-memories and nano-emitters. The first part of the research activity was related to the development of reproducible and controlled protocols for the fabrication of polymeric soft masks for advanced lithographic applications using block copolymers. To this purpose hexagonally packed nanoporous polymeric thin films were fabricated using PS-b-PMMA block copolymers and accurately characterized. Special care was used to the functionalization of the sample surface prior to block copolymer thin film deposition. The effect of the self assembled monolayer of random copolymers conventionally used for surface neutralization was deeply investigated. In particular it was observed that different random copolymer thin films influence the window of thicknesses in which perpendicular orientation of the PMMA domains with respect to the underlying substrate occurs, as well as the characteristic dimensions of the final nanoporous polymeric mask. The possibility of combining “bottom up” self assembly of block copolymers with “top down” patterned templates was then explored to register the periodic domains of the self assembled block copolymer film with the underlying topographic structure. E-beam lithography was used to fabricate trenches in the SiO2 substrate before the deposition of the block copolymer thin films. The nanoporous polymeric mask fabricated during the first part of the research activity was then used as soft mask for patterning the underlying substrate in order to create nanoporous SiO2 hard masks as well as for the fabrication of ordered arrays of Silicon nanodots.
The hexagonally packed nanopores of the polymeric mask were transferred to the underlying SiO2 by reactive ion etching. The effects of the etching parameters on the final characteristics of the nanoporous oxide were deeply investigated. The nanoporous SiO2 template was then used as a backbone for the fabrication of tunable nanoporous Al2O3 substrates by atomic layer deposition growth of thin films of Al2O3 on the SiO2 template. Progressive reduction of the pore size down to complete pore filling was obtained by properly adjusting the thickness of the Al2O3 film. This activity demonstrated the feasibility of fabricating periodic nanostructures surfaces with tunable dimensions well below the 20 nm limit. Moreover, since a large variety of oxide materials can be grown by atomic layer deposition, the proposed methodology provided a general approach for the synthesis of nanoporous oxide with accurate control of pore dimension, size distribution and pore frequency. Ordered arrays of Si nanocrystals were fabricated using the nanoporous polymeric film as a lithographic mask to control the formation of the nanodots. Two different approaches were pursued leading to different configurations where nanodots are embedded/deposited in/on the dielectric matrix. The first approach was based on ion beam synthesis and consisted in the implantation of Si ions into the nanostructured polymeric film to locally introduce the desired ion supersaturation in a limited nanosized area. After removal of the polymeric film, a thermal annealing led to the formation of nanocrystals at a depth depending on the ion energy. The second approach was the lift-off process that included material deposition by e-beam evaporation onto the nano-structured polymeric film and on the exposed substrate regions followed by the subsequent removal of the polymeric template and material excess by wet or dry etching. These arrays of semiconducting nanodots are suitable for the fabrication of Si nanocrystals non volatile memories or Si nanocrystals nanoemitters.
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Wen, Xiaogang. "Organized one dimensional nanomaterials : from preparations to applications /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202005%20WEN.
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Mothoa, Sello Simon. "Synthesis and characterizations of nanostructured MnO2 electrodes for supercapacitors applications." Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5315_1307681987.
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The objective of this research was to develop highly efficient and yet effective MnO2 electrode materials for supercapacitors applications. Most attention had focussed on MnO2 as a candidate for pseudo-capacitor, due to the low cost of the raw material and the fact that manganese is more environmental friendly than any other transition metal oxide system. The surface area and pore distribution of MnO2 can be controlled by adjusting the reaction time. The MnO2 synthesised under optimum conditions display high capacitance, and exhibit good cycle profile. This work investigates the ways in which different morphological structures and pore sizes can affect the effective capacitance. Various -MnO2 were successfully synthesised under low temperature conditions of 70 oC and hydrothermal conditions at 120 oC. The reaction time was varied from 1 to 6 hours to optimise the conditions. KMnO4 was reduced by MnCl.H2O under low temperature, whereas MnSO4.4H2O, (NH4)2S2O8 and (NH4)2SO4 were co-precipitated under hydrothermal conditions in a taflon autoclave to synthesise various -MnO2 nano-structures.
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Mangu, Raghu. "NANOSTRUCTURED ARRAYS FOR SENSING AND ENERGY STORAGE APPLICATIONS." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_diss/207.
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Vertically aligned multi walled carbon nanotube (MWCNT) arrays fabricated by xylene pyrolysis in anodized aluminum oxide (AAO) templates without the use of a catalyst, were integrated into a resistive sensor design. The steady state sensitivities as high as 5% and 10% for 100 ppm of NH3 and NO2 respectively at a flow rate of 750 sccm were observed. A study was undertaken to elucidate (i) the dependence of sensitivity on the thickness of amorphous carbon layers, (ii) the effect of UV light on gas desorption characteristics and (iii) the dependence of room temperature sensitivity on different NH3 and NO2 flow rates. An equivalent circuit model was developed to understand the operation and propose design changes for increased sensitivity.
Multi Walled Carbon NanoTubes (MWCNTs) – Polymer composite based hybrid sensors were fabricated and integrated into a resistive sensor design for gas sensing applications. Thin films of MWCNTs were grown onto Si/SiO2 substrates via xylene pyrolysis using chemical vapor deposition technique. Polymers like PEDOT:PSS and Polyaniline (PANI) mixed with various solvents like DMSO, DMF, 2-Propanol and Ethylene Glycol were used to synthesize the composite films. These sensors exhibited excellent response and selectivity at room temperature when exposed to low concentrations (100ppm) of gases like NH3 and NO2. Effect of various solvents on the sensor response imparting selectivity to CNT – Polymer nanocomposites was investigated extensively. Sensitivities as high as 28% was observed for a MWCNT – PEDOT:PSS composite sensor when exposed to 100ppm of NH3 and -29.8% sensitivity for a MWCNT-PANI composite sensor to 100ppm of NO2.
A novel nanostructured electrode design for Li based batteries and electrochemical capacitor applications was developed and tested. High density and highly aligned metal oxide nanowire arrays were fabricated via template assisted electrochemical deposition. Nickel and Molybdenum nanowires fabricated via cathodic deposition process were converted into respective oxides via thermal treatments and were evaluated as electrodes for batteries and capacitor applications via Cyclic Voltammetery (CV). Several chemical baths were formulated for the deposition of pristine molybdenum nanowires. Superior electrochemical performance of metal (Ni and Mo) oxide nanowires was observed in comparison to the previously reported nano-particle based electrodes.
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Dai, Qing. "Fabrication of patterned one dimension nanomaterials for nanophotonic applications." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610387.
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Moore, Daniel Frankel. "Novel ZnS Nanostructures: Synthesis, Growth Mechanism, and Applications." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-10262006-121555/.
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Thesis (Ph. D.)--Materials Science and Engineering, Georgia Institute of Technology, 2007.Wang, Zhong, Committee Chair ; Snyder, Robert, Committee Member ; Wong, C.P., Committee Member ; Summers, Christopher, Committee Member ; Nie, Shuming, Committee Member.
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Gao, Jinhao. "Multifunctional magnetic nanoparticles : design, synthesis, and applications /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202008%20GAO.
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Basnayaka, Punya A. "Development of Nanostructured Graphene/Conducting Polymer Composite Materials for Supercapacitor Applications." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4864.
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The developments in mobile/portable electronics and alternative energy vehicles prompted engineers and researchers to develop electrochemical energy storage devices called supercapacitors, as the third generation type capacitors. Most of the research and development on supercapacitors focus on electrode materials, electrolytes and hybridization. Some attempts have been directed towards increasing the energy density by employing electroactive materials, such as metal oxides and conducting polymers (CPs). However, the high cost and toxicity of applicable metal oxides and poor long term stability of CPs paved the way to alternative electrode materials. The electroactive materials with carbon particles in composites have been used substantially to improve the stability of supercapacitors. Furthermore, the use of carbon particles and CPs could significantly reduce the cost of supercapacitor electrodes compared to metal oxides. Recent developments in carbon allotropes, such as carbon nanotubes (CNTs) and especially graphene (G), have found applications in supercapacitors because of their enhanced double layer capacitance due to the large surface area, electrochemical stability, and excellent mechanical and thermal properties.
The main objective of the research presented in this dissertation is to increase the energy density of supercapacitors by the development of nanocomposite materials composed of graphene and different CPs, such as: (a) polyaniline derivatives (polyaniline (PANI), methoxy (-OCH3) aniline (POA) and methyl (-CH3) aniline (POT), (b) poly(3-4 ethylenedioxythiophene) (PEDOT) and (c) polypyrrole (PPy). The research was carried out in two phases, namely, (i) the development and performance evaluation of G-CP (graphene in conducting polymers) electrodes for supercapacitors, and (ii) the fabrication and testing of the coin cell supercapacitors with G-CP electrodes.
In the first phase, the synthesis of different morphological structures of CPs as well as their composites with graphene was carried out, and the synthesized nanostructures were characterized by different physical, chemical and thermal characterization techniques, such as Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), UV-visible spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, BET surface area pore size distribution analysis and Thermogravimetric Analysis (TGA). The electrochemical properties of G-CP nanocomposite-based supercapacitors were investigated using Cyclic Voltammetry (CV), galvanostatic charge-discharge and Electrochemical Impedance Spectroscopy (EIS) techniques in different electrolytes, such as acidic (2M H2SO4 and HCl), organic ( 0.2 M LiClO4) and ionic liquid (1M BMIM-PF6) electrolytes.
A comparative study was carried out to investigate the capacitive properties of G-PANI derivatives for supercapacitor applications. The methyl substituted polyaniline with graphene as a nanocomposite (G-POT) exhibited a better capacitance (425 F/g) than the G-PANI or the G-POA nanocomposite due to the electron donating group of G-POT. The relaxation time constants of 0.6, 2.5, and 5s for the G-POT, G-PANI and G-POA nanocomposite-based supercapacitors were calculated from the complex model by using the experimental EIS data.
The specific capacitances of two-electrode system supercapacitor cells were estimated as 425, 400, 380, 305 and 267 F/g for G-POT, G-PANI, G-POA, G-PEDOT and G-PPy, respectively. The improvements in specific capacitance were observed due to the increased surface area with mesoporous nanocomposite structures (5~10 nm pore size distribution) and the pseudocapacitance effect due to the redox properties of the CPs. Further, the operating voltage of G-CP supercapacitors was increased to 3.5 V by employing an ionic liquid electrolyte, compared to 1.5 V operating voltage when aqueous electrolytes were used. On top of the gain in the operating voltage, the graphene nano-filler of the nanocomposite prevented the degradation of the CPs in the long term charging and discharging processes.
In the second phase, after studying the material's chemistry and capacitive properties in three-electrode and two-electrode configuration-based basic electrochemical test cells, coin cell type supercapacitors were fabricated using G-CP nanocomposite electrodes to validate the tested G-CPs as devices. The fabrication process was optimized for the applied force and the number of spacers in crimping the two electrodes together. The pseudocapacitance and double layer capacitance values were extracted by fitting experimental EIS data to a proposed equivalent circuit, and the pseudocapacitive effect was found to be higher with G-PANI derivative nanocomposites than with the other studied G-CP nanocomposites due to the multiple redox states of G-PANI derivatives. The increased specific capacitance, voltage and small relaxation time constants of the G-CPs paved the way for the fabrication of safe, stable and high energy density supercapacitors.
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Merlettini, Andrea <1989>. "Micro-nanostructured polymeric materials with specific functionalities for advanced biomedical applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amsdottorato.unibo.it/8834/1/Thesis_Merlettini.pdf.
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The possibility to tune material properties up to nanoscale represents a great opportunity for the scientific community to obtain devices capable to fulfill the always new medical demands. During this Thesis project micro and nano-structured polymeric materials have been used in the field of drug delivery and tissue engineering. Three different research lines have been explored: (i) the use of polymeric fibrous systems as drug and nanoparticles carriers, (ii) design and evaluation of novel shape memory polymers to produce shape memory scaffolds and (iii) development of smart affinity membranes.
Electrospinning were exploited to obtain polymeric fibrous carriers made of different biodegradable and bioresorbable polymers, such us Poly(lactic-acid) and Poly(lactic-co-glycolic). The obtained biodegradable carriers have been exploited to achieve controllable particles release as well as, to obtain composites capable to deliver two drugs simultaneously with controllable and predictable kinetics.
The possibility to obtain electrospun scaffolds capable of interconverting between a temporary and a permanent shape with the application of a thermal stimulus was explored. In this context, two polymers have been designed to behave as shape memory materials in the range of human body temperature.
Finally smart affinity membranes have been studied. This kind of materials are capable to detect specific molecules or biomacromolecules from complex mixtures, finding useful applications in the biomedical field as diagnostic and therapeutic devices. Smart affinity membranes might be used for example to detect specific kind of cells by exploiting the binding interaction between an antibody and cell receptors. During this thesis project poly(L-lactic acid) electrospun scaffolds conjugated with antibodies have been produced and the efficacy of different functionalization methods to generate the –COOH group necessary to perform the antibodies conjugation was investigated.
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Bovo, Laura. "Nanostructured Materials Based on ZnO for Cataltytic, Optical and Magnetic Applications." Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3423214.
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ZnO based materials, such as Zn1-xTMxO (TM = Mn, Co, Cu) nanopowders, were synthesised by a Sol gel route to investigate their properties in three fields: catalysis, optics and magnetism. These materials were characterised by complementary techniques such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS) and UV-Vis Spectroscopy. The fine structure and electronic properties of these nanomaterials were studied by X-ray Absorption Spectroscopy (XAS) and Electron Paramagnetic Resonance (EPR). These techniques give site, element and chemical specific measurements which allow a better understanding of the interplay and role of each element in the functionality of the system.
The catalytic performance of undoped and Cu-doped ZnO nanosystems were tested with respect to the Methanol Steam Reforming (MSR) reaction. Contrary to what is generally accepted in literature, the results obtained in this study demonstrate that ZnO also plays a prominent role in this catalytic process. The structure–activity relationship of ZnO and copper-doped ZnO catalysts described in this work give an insight into the effective function of each component which is vital to enable the rational design of improved catalysts.
The luminescence properties of the doped Zn1-xTMxO nanopowders were investigated with X-ray Excited Optical Luminescence (XEOL) techniques: these experiments provided a better understanding of the relationship between the electronic structure of the systems and their properties. Results showed how it is possible to manipulate the luminescence of ZnO grown by Sol gel by modifying synthesis conditions – i.e. the annealing temperature and the nature and concentration of the transition metal ion.
Finally, preliminary results were presented on the materials' magnetic properties, obtained by SQUID (Superconducting Quantum Interference Devices) magnetometry, where the coexistence of different contributions has been detected. Even though further characterisation is still needed, this study is a step towards the determination of the nature of magnetic interactions in such systems, of which there has been considerable debate in the scientific community.Materiali a base di ZnO, in particolare nano-polveri di Zn1-xTMxO (TM = Mn, Co, Cu), sono stati sintetizzati via Sol gel per studiarne le proprietà in tre diversi campi applicativi quali la catalisi, l’ottica ed il magnetismo. Tali materiali sono stati caratterizzati utilizzando diverse tecniche, complementari tra loro, quali X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS) e UV-Vis Spectroscopy. X-ray Absorption Spectroscopy (XAS) ed Electron Paramagnetic Resonance (EPR) vengono invece impiegate per studiare le proprietà elettroniche e di struttura fine delle nano-polveri. Tali caratterizzazioni si sono dimostrate fondamentali per la comprensione delle proprietà del sistema ed, in particolare, per cercare di identificare le interazioni sussistenti tra struttura, composizione, morfologia dei materiali e la loro capacità di espletare una determinata funzionalità. Nano-polveri di ZnO tal quali e drogate con ioni rame vengono testate come catalizzatori nella reazione di Steam Reforming del metanolo. I risultati ottenuti in questo studio dimostrano il ruolo attivo dell’ossido di zinco nel processo catalitico, contrariamente a quanto solitamente accettato in letteratura. La relazione sussistente tra struttura-attività nei catalizzatori a base di ZnO permette di ottenere informazioni circa l’effettiva funzione di ogni componente, aspetto di estrema importanza per la progettazione razionale di catalizzatori con elevate performance. Le proprietà di luminescenza dei sistemi drogati Zn1-xTMxO vengono studiate mediante spettroscopia X-ray Excited Optical Luminescence (XEOL); tali esperimenti forniscono una migliore comprensione del rapporto che sussiste tra la struttura elettronica dei sistemi in esame e le loro proprietà di emissione. I risultati mostrano come sia possibile modulare la luminescenza di ZnO prodotto via Sol gel modificando le condizioni di sintesi – i.e. temperatura di trattamento, natura e concentrazione del metallo di transizione utilizzato come drogante. Infine, risultati preliminari sulle proprietà magnetiche dei materiali ottenuti mediante SQUID magnetometer (Superconducting Quantum Interference Devices) hanno rivelato la coesistenza di diversi contributi magnetici. Nonostante ulteriori caratterizzazioni siano sicuramente necessarie, questo studio si è rivelato un passo avanti verso una comprensione della natura delle interazioni magnetiche in tali sistemi, da tempo causa di vivace dibattito nella comunità scientifica.
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Wang, Shu Jun. "Applications of graphene for transparent conductors and polymer nanocomposites /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?MECH%202009%20WANGS.
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Mohin, Jacob W. "Nanostructured π-Electron Materials for Energy Applications Derived from Macromolecular Self-Assembly." Research Showcase @ CMU, 2015. http://repository.cmu.edu/dissertations/1045.
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Globalization and climate change have driven the need to develop new technologies which can provide clean, plentiful energy from renewable sources. This work was focused on the application of nanostructured π-electron materials derived from carbon-based macromolecules towards capturing, converting, and storing energy. Nanostructures are beneficial in this role as they provide high interfacial area and unique electronic properties which can be harnessed to perform chemistry relevant to energy conversion and storage. This work was focused on the characterization, materials development, and device application of two nanostructured systems: (i) poly(3-hexyl)thiophene (P3HT) blended with phenyl(C-61)butyric acid methyl ester (PCBM), and (ii) copolymer-templated nitrogen-doped nanoporous carbons (CTNCs). In both systems, nanomorphology has pronounced impact on the performance of devices made from such materials. P3HT/PCBM blends find application as a photovoltaic material, where the phase-separated morphology is crucial for efficient photogenerated charge collection. Despite widespread recognition of the importance of morphology in P3HT/PCBM photovoltaics, a robust understanding of the unique packing motif of P3HT on the morphology of blended structures has yet to emerge. This thesis addresses this deficiency by developing methods which connects real-space atomic force microscopy images with inverse space x-ray scattering patterns to analyze poorly ordered two-phase systems. The application of this method allowed for quantitative measurement of the phase ratios of P3HT/PCBM nanostructured blends, utilizing the Porod length of inhomogeneity and the Bragg length associated with pseudo-fibrillar P3HT morphologies. The results showed that P3HT possesses void space originating from molecular weight dispersity inherent to polymerization, which accounts for solid-phase solubility of PCBM in P3HT. X-ray scattering and atomic force microscopy were also used in part to characterize CTNCs. Past success using CTNCs as electrocatalysts and supercapacitors motivated research towards increasing their surface area by utilizing a lower molecular weight precursor polymer. Atom-transfer radical polymerization was utilized to synthesize block copolymers consisting of polystyrene and polyacrylonitrile, but it was found their surface areas were lower than those achieved in previous work. Careful structural analysis by variable temperature x-ray scattering showed that crystallization of polyacrylonitrile drives morphological changes on heating, increasing domain spacing. Further thermal analysis showed that polystyrene interferes with the crosslinking of polyacrylonitrile, which may cause morphological collapse leading to low surface area. A feature of CTNCs noted in past and present studies is their sizeable surface area consisting of pores <1 nanometer (micropores). Differential scanning calorimetry showed that reactive chain ends left behind by polymerization might play a role in disrupting the crosslinking process, resulting in a material with sizeable microporosity, which could be used to engineer dual pore-size materials. Finally, CTNCs were utilized for heterogeneous catalytic production of hydrogen from water, with electrons provided by both light and external circuitry. Their performance was correlated with nitrogen heteroatom content, conductivity, and nanomorphology, and shown to match that of noble metals. The lessons learned about nanomorphology in P3HT/PCBM and CTNCs highlight the importance of nanomorphology in energy devices and will serve as insight for materials design in future studies.
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Giuffrida, Antonino Emanuele. "Surface engineered nanostructured oxides as multifunctional materials for environmental and biomedical applications." Doctoral thesis, Università di Catania, 2017. http://hdl.handle.net/10761/3898.
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Durante i tre anni del dottorato di ricerca in Scienze dei Materiali e Nanotecnologie presso il dipartimento di Scienze Chimiche dell Università degli studi di Catania mi sono occupato della ingegnerizzazione di superfici di ossidi nanostrutturati, con opportune molecole funzionali, al fine di ottenere dei materiali ibridi multifunzionali capaci di poter essere utilizzati in vari ambiti tecnologici. L approccio utilizzato per ottenere dei sistemi di questo tipo è stato quello già noto del bottom-up ovvero l utilizzo di mattoni molecolari che si auto-assemblano per via di un meccanismo intrinseco di riconoscimento chimico. Nello specifico le molecole funzionali utilizzate sono state: miscele di acidi fosfonici, che si legano covalentemente alla superficie di ossidi metallici, e diversi tipi di cavitandi (sintetizzati ad hoc presso l università di Parma dal gruppo del Prof. Enrico Dalcanale) nonché stabilizzatori, marker e dyes.
Questo approccio ha permesso la realizzazione di sistemi in grado di essere utilizzati nei seguenti ambiti:
1) Rilevazione di composti organici volatili (VOC) su nanostrutture di ZnO
2) Purificazione di acqua inquinata mediante nanoparticelle di Fe3O4
3) Incremento nel trasporto di farmaci all interno di cellule
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ROONEY, MILES. "Self-assembled, nanostructured organic materials for applications in electronics and optoelectronic devices." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2018. http://hdl.handle.net/10281/199099.
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l'indagine di due metodi per il controllo molecolare della nano-morfologia di dispositivi opto-elettronici. In primo luogo, un metodo di fotoreticolazione per la creazione di strati semiconduttori insolubili adatti per dispositivi fotovoltaici organici. Una grande serie di semiconduttori squaraine sono studiati in un dispositivo di eterogiunzione di massa. Questo approccio è esteso a nuclei semiconduttori di dichetopirrolopirrolo e naftalene diimmide. Lo studio dettagliato della struttura del film dei materiali viene effettuato.
Il secondo approccio è un'indagine sull'applicabilità dei pigmenti latenti per l'optoelettronica organica. Una serie di fotovoltaici organici sono prodotti in architetture di eterogiunzione planare a doppio strato. I dispositivi a film sottile sono testati con una varietà di interstrati e parametri di elaborazione. Il controllo della nanostruttura di questi dispositivi a film sottile viene esaminato con studi a raggi X. Incorporazione di riflettività a raggi X, raggi X speculari, raggi X a gradiente e studi a raggi x grandangolari. In questo modo la massa e le interfacce dei dispositivi a film sottile possono essere esaminate e caratterizzate. L'approccio del pigmento latente viene applicato anche al campo dei transistor ad effetto di campo organico come lo strato semiconduttore attivo. La natura resistente ai solventi di un pigmento semiconduttore genitore mostra un vantaggio sostanziale per la fabbricazione di tali dispositivi. L'esclusivo riarrangiamento cristallino che si verifica dopo la deprotezione di un pigmento latente determina un miglioramento della mobilità del portatore di carica fino a tre ordini di grandezza mentre estende le possibilità di elaborazione delle successive fasi di deposizione necessarie per completare un transistor ad effetto di campo organico
Queste due tecniche sono sviluppate pensando alla compatibilità industriale. Come tale, viene esplorato un nuovo metodo sintetico per una produzione facile, economica ed ecocompatibile di semiconduttori organici. Un ambiente di reazione micellare viene creato attraverso l'uso del comune tensioattivo e dell'eccipiente di droga Kolliphor EL. L'esclusivo nucleo privo di ossigeno di questo tensioattivo offre un nuovo ambiente per l'esecuzione di comuni reazioni di accoppiamento incrociato quali reazioni Suzuki-Miyaura, Stille e Heck in aria e acqua a temperatura ambiente. Alte rese di oltre il 90% vengono recuperate per nuclei semiconduttori organici complessi. La versatilità di questo approccio è estesa dall'uso del toluene come co-solvente. Questo sistema di co-solvente porta allo sviluppo di un'emulsione che può essere utilizzata per eseguire analisi chimiche complesse. La chimica dell'emulsione offre un modo unico per la sintesi di semiconduttori organici complessi con basso carico di catalizzatore metallico ad alto rendimento.the investigation of two methods for molecular control of the nano-morphology of opto-electronic devices. Firstly, a photocrosslinking method for creating insoluble semiconductor layers suitable for organic photovoltaic devices. A large series of squaraine based semiconductors are investigated in a bulk heterojunction device. This approach is extended to diketopyrrolopyrrole and naphthalene diimide semiconducting cores. Detailed study of the materials film structure is carried out. The second approach is an investigation of the applicability of latent pigments for organic opto-electronics. A series of organic photovoltaics are produced in planar bilayer and bulk heterojunction architectures. The thin film devices are tested with a variety of interlayers and processing parameters. The control of the nanostructure of these thin film devices is examined with X-ray studies. Incorporating X-ray reflectivity, Specular x-ray, Gradient temperature X-ray and grazing wide angle x-ray studies. In this manner the bulk and interfaces of thin film devices can be examined and characterised. The latent pigment approach is also applied to the field of organic field effect transistors as the active semiconducting layer. The solvent resistant nature of a parent semiconducting pigment shows a substantial benefit to the fabrication of such devices. The unique crystalline rearrangement which occurs upon deprotection of a latent pigment results in an improvement in charge carrier mobility of up to three orders of magnitude while extending the processing possibilities of the subsequent deposition steps required to complete an organic field effect transistor These two techniques are developed with the thoughts of industrial compatibility in mind. As such, a novel synthetic method for facile, cheap, and environmentally friendly production of organic semiconductors is explored. A micellar reaction environment is created through the use of the common surfactant and drug excipient Kolliphor EL. The unique oxygen free core of this surfactant offers a new environment for carrying out common cross coupling reactions such as Suzuki-Miyaura, Stille and Heck reactions in air and water at ambient temperature. High Yields of over 90% are recovered for complex organic semiconducting cores. The versatility of this approach is extended by the use of toluene as a co-solvent. This co-solvent system results in the development of an emulsion which can be used to perform complex chemistries. Emulsion chemistry offers a unique way to synthesis complex organic semiconductors with low metallic catalyst loading at high yield.