Transparent conducting oxides (TCOs) combine optical transparency in the visible region with a high electrical conductivity. In2O3 doped with Sn (widely, but somewhat misleadingly, known as indium tin oxide or ITO) is at present the most important TCO, with applications in liquid crystal displays, touch screen displays, organic photovoltaics and other optoelectronic devices. Surprisingly, many of its fundamental properties have been the subject of controversy or have until recently remained unknown, including even the nature and magnitude of the bandgap. The technological importance of the material and the renewed interest in its basic physics prompted the research described in this thesis. This thesis aims (i) to establish conditions for the growth of high-quality In2O3 nanostructures and thin films by oxygen plasma assisted molecular beam epitaxy and (ii) to conduct comprehensive investigations on both the surface physics of this material and its structural and electronic properties. It was demonstrated that highly ordered In2O3 nanoislands, nanorods and thin films can be grown epitaxially on (100), (110) and (111) oriented Y-stabilized ZrO2 substrates respectively. The mismatch with this substrate is -1.7%, with the epilayer under tensile strain. On the basis of ab initio density functional theory calculations, it was concluded that the striking influence of substrate orientation on the distinctive growth modes was linked to the fact that the surface energy for the (111) surface is much lower than for either polar (100) or non-polar (110) surfaces. The growth of In2O3(111) thin films was further explored on Y-ZrO2(111) substrates by optimizing the growth temperature and film thickness. Very thin In2O3 epilayers (35 nm) grew pseudomorphically under high tensile strain, caused by the 1.7% lattice mismatch with the substrate. The strain was gradually relaxed with increasing film thickness. High-quality films with a low carrier concentration (5.0  1017 cm-3) and high mobility (73 cm2V-1s-1) were obtained in the thickest films (420 nm) after strain relaxation. The bandgap of the thinnest In2O3 films was around 0.1 eV smaller than that of the bulk material, due to reduction of bonding-antibonding interactions associated with lattice expansion. The high-quality surfaces of the (111) films allowed us to investigate various aspects of the surface structural and electronic properties. The atomic structure of In2O3 (111) surface was determined using a combination of scanning tunnelling microscopy, analysis of intensity/voltage curves in low energy electron diffraction and first-principles ab initio calculations. The (111) termination has an essentially bulk terminated (1 × 1) surface structure, with minor relaxations normal to the surface. Good agreement was found between the experimental surface structure and that derived from ab initio density functional theory calculations. This work emphasises the benefits of a multi-technique approach to determination of surface structure. The electronic properties of In2O3(111) surfaces were probed by synchrotron-based photoemission spectroscopy using photons with energies ranging from the ultraviolet (6 eV) to the hard X-ray regime (6000 eV) to excite the spectra. It has been shown that In2O3 is a highly covalent material, with significant hybridization between O and In orbitals in both the valence and the conduction bands. A pronounced electron accumulation layer presents itself at the surfaces of undoped In2O3 films with very low carrier concentrations, which results from the fact the charge neutrality level of In2O3 lies well above the conduction band minimum. The pronounced electron accumulation associated with a downward band bending in the near surface region creates a confining potential well, which causes the electrons in the conduction band become quantized into two subband states, as observed by angle resolved photoemission spectra (ARPES) Fermi surface mapping. The accumulation of high density of electrons near to the surface region was found to shrink the surface band gap through many body interactions. Finally epitaxial growth of In2O3 thin films on α-Al2O3(0001) substrates was investigated. Both the stable body centred cubic phase and the metastable hexagonal corundum In2O3 phase can be stabilized as epitaxial thin films, despite large mismatches with the substrate. The growth mode involves matching small but different integral multiples of lattice planes of the In2O3 and the substrate in a domain matching epitaxial growth mode.

Transparente Elektroden finden breite Verwendung in unterschiedlichen kommerziellen Produkten. Dünnschichtsolarzellen basieren ebenso auf diesen Funktionsschichten wie Displays oder organische Leuchtdioden. Im Falle von Dünnschichtsolarzellen kann durch gezielte Einstellung der Oberflächentextur der transparenten Elektrode ein entscheidender Einfluss auf die erreichbare Effizienz genommen werden. Dabei wird eine Verlängerung der Weglänge des Lichtes im Absorbermaterial durch Mehrfachreflexionen angestrebt. Häufig werden dafür Schichten transparenter leitfähiger Oxide (TCO) gezielt texturiert. Eine weitere Möglichkeit zur Erzeugung transparenter Elektroden stellt die Verwendung feiner Metallgitter dar. Diese ermöglichen hohe Leitfähigkeiten im Bereich der Gitterstege und hohe Transparenz im Bereich zwischen den Stegen. In dieser Arbeit sollte ein auf nasschemischen Prozessen basierendes Verfahren entwickelt werden, mit dem es möglich ist, sowohl strukturierte TCO-Elektroden als auch Metallgitter unterschiedlicher Geometrien gezielt herzustellen. Die Leistungsfähigkeit der Elektroden sollte anhand der Integration in entsprechende Bauteile bewertet werden. Namentlich sollte dieser Prozess für Cd2SnO4 (engl. Cadmium Tin Oxide, CTO) als ein TCO-Material hoher Transparenz und Leitfähigkeit sowie für Silber und Kupfer als metallische Systeme anwendbar sein. Als zielführende Methode kam die Nanoprägelithographie (von engl. Nanoimprint Lithography, NIL) zum Einsatz. Dieses Verfahren erlaubt die schnelle, einfache und kostengünstige Herstellung strukturierter Oberflächen. Grundsätzlich wird dazu ein strukturierter Elastomerstempel in eine Schicht eines zu vernetzenden Materials gepresst. Während des Pressens findet die Vernetzung statt. Nach anschließender Separation von Stempel und Schicht resultiert eine strukturierte Oberfläche. Gängige Präkursorensysteme für anorganische Verbindungen, bei denen Vernetzungsprozesse ablaufen, stellen Sol-Gel-Methoden und sogenannte polymere Präkursoren dar. Für letztere werden Metallzitrate mit Ethylenglykol verestert, um ein vernetztes Polymer zu generieren. Nach thermischem Entfernen der Organik bleibt das Metalloxid zurück. Im Rahmen dieser Arbeit ist ein Präkursorensystem entwickelt worden, das Metallionen komplexiert, auf Glassubstrate beschichtet werden kann und eine thermische Polymerisation erlaubt. Aus dem erhaltenen polymeren Präkursor konnten die Zielverbindungen durch thermisches Zersetzen einerseits in Pulverform und andererseits über vorhergehende Schleuderbeschichtung in Form dünner Schichten erhalten werden. Im Falle des kubischen Cd2SnO4 wurde im Rahmen dieser Arbeit erstmals eine Nanopulver-Synthese mit phasenreinem Produkt aus flüssigem Präkursor beschrieben. Dafür stellten sich der Anteil der verwendeten organischen Bestandteile sowie die Zersetzungsgeschwindigkeit als entscheidende Einflussparameter heraus. Zudem wurden CTO Dünnschichten mit dem beschriebene Präkursor hergestellt. Eine optimale Brenntemperatur zur Erzeugung phasenreiner CTO-Schichten von 700 ‰ wurde ermittelt. Die Zersetzungsgeschwindigkeit (bzw. Aufheizrate) beeinflusste die Oberflächenmorphologie der erhaltenen Schichten maßgeblich. Eine schrittweise Zersetzung (100 ‰°C, 200 °C‰, Zieltemperatur) führte dabei in effizienter Weise zu kompakten Schichten. Diese zeigten sehr gute optische und elektronische Eigenschaften. So konnten etwa 300 nm dicke CTO-Schichten mit spezifischen Widerständen von ca. 1 • 10^(−5) Ohm m bei einer Transmission von etwa 80 % (inklusive Glassubstrat) erhalten werden. Derartige CTO-Schichten konnten erfolgreich als transparente Frontelektroden für a-Si Dünnschichtsolarzellen verwendet werden. Ein positiver Einfluss periodischer Linienstrukturen auf die Lichteinfangeigenschaften und den resultierenden Photostrom im Vergleich zu flachen CTO-Schichten wurde bestätigt. Auch für die Herstellung von CdTe-Dünnschichtsolarzellen konnten die CTO-Schichten erfolgreich eingesetzt werden. Die erreichten Effizienzen lagen jedoch lediglich im Bereich von 3 bis 3,6 %. Ein signifikanter Unterschied zwischen flachen und strukturierten Proben konnte nicht ausgemacht werden. Durch die reduzierenden Eigenschaften von Zitronensäure und Ethylenglykol gegenüber Ag+ und Cu2+ Ionen war es möglich, die Metalle in elementarer Form durch einfache thermische Behandlung des Präkursors zu erhalten. Während dieser Prozess für silberhaltige Systeme relativ einfach zu realisieren war, musste bei kupferhaltigen Proben die Bildung oxidischer Nebenphasen festgestellt werden. So war für Letzteres eine reduktive Nachbehandlung vollständig oxidierter Proben im Wasserstoffplasma zielführend und lieferte leitfähige Dünnschichten mit hohem Cu(0)-Anteil. Im Falle von Silber führte eine geeignete thermische Behandlung der Präkursorschicht zu dünnen, leitfähigen Silberschichten mit spezifischen Widerständen von ca. 6 • 10^(−8) Ohm m (Festkörper: ca.1 • 10^(−8) Ohm m). Die Übertragung des NIL-Prozesses gelang sowohl für silber- als auch kupferhaltige Systeme. Mit NIL-strukturierten Silberdünnschichten gelang so die Herstellung semitransparenter Elektroden mit spezifischen Widerständen von 2,2 • 10^(−7) Ohm m, welche in Elektrolumineszenzbauteilen verwendet wurden. Aufgrund der relativ niedrigen Temperaturen, die für die Zersetzung des Silberpräkursors nötig waren (ca. 250 ‰ ), war die Fertigung entsprechender Elektroden und Bauteile auch auf Polyimidfolien möglich. Insgesamt bleibt die Erkenntnis, dass NIL-strukturierte dünne Schichten erfolgreich in optoelektronische Bauteile integriert werden konnten. Variable Präkursorsysteme erlauben die Herstellung verschiedener Schichten und somit Anwendungen in unterschiedlichen Bauteilen. Polymere Präkursoren haben sich als geeignet für dieses Vorgehen erwiesen und können relativ einfach auf diverse oxidische Stoffsysteme übertragen werden. Gleichzeitig eignen sie sich zur Herstellung metallischer transparenter Elektroden durch NIL-Strukturierung, was insbesondere im Hinblick auf flexible Bauteile von Vorteil ist.

Polymer/inorganic nanoparticle hybrid thin films, primarily composed of functional inorganic nanoparticles, are of great interest to researchers because of their interesting electronic, photonic, and optical properties. In the past two decades, layer-by-layer (LbL) assembly has become one of the most powerful techniques to fabricate such hybrid thin films. This method offers an easy, inexpensive, versatile, and robust fabrication technique for multilayer formation, with precisely controllable nanostructure and tunable properties. In this thesis, various ways to control the structure of hybrid thin films, primarily composed of polyelectrolytes and indium tin oxide (ITO), are the main topics of study. ITO is one of the most widely used conductive transparent oxides (TCOs) for applications such as flat panel displays, photovoltaic cells, and functional windows. In this work, polyethyleneimine (PEI) was used to stabilize the ITO suspensions and improve the film buildup rate during the LbL assembly of poly(sodium 4-styrenesulfonate) (PSS) and ITO. The growth rate was doubled due to the stronger interaction forces between the PSS and PEI-modified ITO layer. The assembly of hybrid films was often initiated by a polyelectrolyte precursor layer, and the characteristics of the precursor layer were found to significantly affect the assembly of the hybrid thin films. The LbL assembly of ITO nanoparticles was realized on several substrates, including cellulose fibers, write-on transparencies, silicon wafers, quartz crystals, and glasses. By coating the cellulose fibers with ITO nanoparticles, a new type of conductive paper was manufactured. By LbL assembly of ITO on write-on transparencies, transparent conductive thin films with conductivity of 10⁻⁴ S/cm and transparency of over 80 % in the visible range were also prepared. As a result of this work on the mechanisms and applications of LbL grown films, the understanding of the LbL assembly of polyelectrolytes and inorganic nanoparticles was significantly extended. In addition to working with ITO nanoparticles, this thesis also demonstrated the ability to grow bicomponent [PEI/SiO₂]n thin films. It was further demonstrated that under the right pH conditions, these films can be grown exponentially (e-LbL), resulting in much thicker films, consisting of mostly the inorganic nanoparticles, in much fewer assembly steps than traditional linearly grown films (l-LbL). These results open the door to new research opportunities for achieving structured nanoparticle thin films, whose functionality depends primarily on the properties of the nanoparticles.

The continuous microreactor-assisted solution deposition (MASD) process was used for the deposition of CdS thin films on fluorine-doped tin oxide (FTO) glass. The MASD system, including a T-junction micromixer and a microchannel heat exchanger is capable of isolating the homogeneous particle precipitation from the heterogeneous surface reaction. The results show a dense nanocrystallite CdS thin films with a preferred orientation at (111) plane. Focused-ion-beam was used for TEM specimen preparation to characterize the interfacial microstructure of CdS and FTO layers. The band gap of the microreactor-assisted deposited CdS film was determined at 2.44 eV. X-ray Photon Spectroscopy show the bindings of energies of Cd 3d₃/₂, Cd 3d₅/₂, S 2p₃/₂ and S 2p₁/₂ at 411.7 eV, 404.8 eV, 162.1 eV, and 163.4 eV, respectively. The film growth kinetics was studied by measuring the film thickness deposited from 1 minute to 15 minutes in physical (FIB-TEM) and optical (reflectance spectroscopy) approaches. A growth model that accounts for the residence time in the microchannel using empirical factor (η) obtained from previous reported experimental data. Applying this factor in the proposed modified growth model gives a surface reaction rate of 1.61*10⁶ cm⁴ mole⁻¹s⁻¹, which is considerable higher than the surface reaction rates obtained from the batch CBD process. With the feature of separating homogeneous and heterogeneous surface reaction, the MASD process provides the capability to tailor the surface film growth rate and avoid the saturation growth regime in the batch process. An in situ spectroscopy technique was used to measure the UV-Vis absorption spectra of CdS nanoparticles formed within the continuous flow microreactor. The spectra were analyzed by fitting the sum of three Gaussian functions and one exponential function in order to calculate the nanoparticle size. This deconvolution analysis shows the formation of CdS nanoparticles range from 1.13 nm to 1.26 nm using a residence time from 0.26 s to 3.96 s. Barrier controlled coalescence mechanism seems to be a reasonable model to explain the experimental UV-Vis data obtained from the continuous flow microreactor, with a rate constant k' value of 2.872 s⁻¹. Using CFD, low skewness value of the RTD curve at high flow rate (short τ) suggests good radial mixing at high flow rate is responsible for the formation of smaller CdS nanoparticles with a narrower size distribution. The combination of CdS nanoparticle solution with MASD process resulted in the hindrance of CdS thin film deposition. It is hypothesized that the pre-existing sulfide (S²⁻) ions and CdS nanoparticles changes the chemical species equilibrium of thiourea hydrolysis reaction. Consequently, the lack of thiourea slows down the heterogeneous surface reaction. To test the scalability of the MASD process, a flow cell and reel-to-reel (R2R)-MASD system were setup and demonstrated for the deposition of CdS films on the FTO glass (6" x 6") substrate. The film deposition kinetics was found to be sensitive to the flow conditions within the heat exchanger and the substrate flow cell. The growth kinetics of the CdS films deposited by R2R-MASD process was investigated by with a deposition time of 2.5 min, 6.3 min, and 9 min. In comparison with the continuous MASD process, the growth rate in R2R-MASD is higher, however more difficult to obtain a linear relationship with the deposition time. / Graduation date: 2012 / Access restricted to the OSU Community at author's request from Jan. 13, 2012 - Jan. 13, 2013

Σκοπός της παρούσας εργασίας είναι αρχικά να μελετηθεί η επιφάνεια του οξειδίου ινδίου κασσιτέρου που έχει αποτεθεί σε υπόστρωμα ΡΕΤ και να γίνουν πάνω σε αυτήν χημικές επεξεργασίες αλλά και ιοντοβολή, ώστε να παρατηρηθούν τι επιδράσεις έχουν αυτές οι κατεργασίες στην επιφάνεια και ενδεχομένως στο έργο εξόδου. Οι κατεργασίες επιλέχθηκαν επειδή είναι γνωστή από την βιβλιογραφία η επίδρασής τους στο ΙΤΟ που όμως έχει αποτεθεί σε γυαλί, και η σύγκριση με τα δικά μας αποτελέσματα θα δώσει χρήσιμες πληροφορίες για τις διαφορές των δύο υλικών καθώς και αν οι κατεργασίες αυτές μπορούν να χρησιμοποιηθούν και αν είναι χρήσιμες για την αύξηση του έργου εξόδου του ΙΤΟ-ΡΕΤ. Επίσης, στη συνέχεια έγιναν αποθέσεις οργανικού ημιαγώγιμου υλικού (NiPc) πάνω στο υπόστρωμα ΙΤΟ-ΡΕΤ το οποίο είχε επεξεργαστεί χημικά, με σκοπό να προσδιοριστεί η ηλεκτρονική δομή της διεπιφάνειας του οργανικού και του υποστρώματος, ώστε να μελετηθεί η επίδραση του ΙΤΟ-ΡΕΤ στην συμπεριφορά της διεπιφάνειας και να διαπιστωθεί η πιθανή εφαρμογή τους σε ηλεκτρονικές διατάξεις. / The purpose of this thesis is to study the surface of indium tin oxide deposited on PET substrate after some chemical treatments and Argon Sputtering, in to order to investigate what effects these treatments have on the surface and possibly in the work function. The treatments were chosen because it is known from the literature the influence they have on the ITO, but which it has been deposited on glass, and a comparison of our results will provide useful information about differences between the two materials, and whether these treatments can be useful for increasing the work function of ITO-PET. Also, it was deposited organic semiconductor material (NiPc) onto the ITO-PET substrate that was chemically processed in order to determine the electronic structure at the interface of organic substrate and to study the effect of ITO-PET in the behavior of interface and to determine its possible application in electronic devices.

The catalytic activity of metal complex exhibiting Lewis acid character (dibutyltin diacetate, dibutyltin dilaurate, butylstannoic acid and di-n-butyl-oxostannane) was investigated. These catalytic complexes have been tested in the alcoholysis of soybean and castor oils, aiming to obtain a mixture of fatty acid alkyl esters, called biodiesel. In the transesterification experiments of vegetable oils, the reactions were performed using three types of reactors. The first one consisted in a glass reactor connected to a reflux condenser (RVCR). The second device consisted of a stainless steel reactor (RP), hermetically sealed, fitted with a pressure gauge and a temperature controller. The third one was adapted to be used on a microwave system. On the last two reactor systems, the alcoholysis of triglycerides was also developed at vigorous conditions, at temperatures ranging from 80 °C and 150 °C. Comparing all reactions, the results show that the most reactive catalysts using the RVCR on the methanolysis of soybean oil are DBTDA and DBTDL with comparable performances. However, in the same reaction conditions, very low yields were observed using castor oil, and no generalizations could be pointed out. When RP were employed, better yields were obtained. When the temperature raise from 80 to 150 ºC, all catalytic systems display similar performances, indicating that temperature and solubility have significant influences on these type of catalytic systems. Very low reaction yield were observed when the microwave reactor was employed. This observation must be due to the very low rate of stirring performed on this type of reactor. In a second part of this work, it was evaluated the performance of catalysts based on tin oxide (SnO2), sulfated or not, in transesterification or esterification reactions of soybean oil and its fatty acids derivatives, respectively, in the presence of methanol. The low activity verified on these systems must be related to their structural characteristics. / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Neste trabalho foi investigada a atividade catalítica de quatro complexos metálicos exibindo caráter ácido de Lewis: dibutildiacetato de estanho, dibutildilaurato de estanho, óxido de dibutil estanho e ácido butilestanóico. Esses complexos catalíticos foram testados na alcoólise do óleo de soja e de mamona, visando a obtenção de uma mistura de ésteres alquílicos de ácidos graxos, denominada biodiesel. Nos experimentos de transesterificação dos óleos vegetais, as reações foram realizadas em três tipos de reatores. O primeiro equipamento foi composto de um reator de vidro acoplado a um condensador de refluxo (RVCR). O segundo equipamento foi composto de um reator de aço inox (RP), hermeticamente fechado, equipado com um manômetro e um controlador de temperatura. O terceiro reator empregado era adaptado para ser utilizado em um sistema de microondas. Nos dois últimos sistemas de reatores, a alcoólise dos triglicerídeos foi desenvolvida em condições mais enérgicas de reação, em temperaturas que variaram entre 80 °C e 150 °C. Comparando-se todas as reações, os resultados obtidos indicam que o emprego do RVCR na metanólise do óleo de soja, os catalisadores mais ativos são o DBTDA e o DBTDL com desempenhos comparáveis. Por outro lado, empregando-se o óleo de mamona, nessa condição reacional, os rendimentos foram muito baixos, não permitindo obter generalizações. Quando do uso do RP, rendimentos superiores aos observados com o RVCR são obtidos e à medida que a temperatura aumenta de 80 a 150 ºC as reatividades dos sistemas catalíticos tornam se bastante semelhantes, indicando que fatores como temperatura e solubilidade têm influência significativa nesse tipo de sistemas catalíticos. Com o emprego do reator microondas, os rendimentos reacionais foram inferiores, provavelmente devido à baixa velocidade de agitação que tal reator pode realizar. Numa segunda parte do trabalho, foi realizado um estudo do desempenho de catalisadores a base de óxido de estanho (SnO2), sulfatado ou não, em reações de transesterificação ou esterificação de óleo de soja e seus ácidos graxos, respectivamente, na presença de metanol. A baixa atividade dos catalisadores foi relacionada às características texturais dos mesmos.

The development of heterogeneous catalysts, which are efficient and easy recovery, is major technological challenges faced, linked to environmental and economic concerns. In the present work we studied the catalytic SnO2 systems, MoO3 and SnO2/MoO3 in the conversion of fructose, with particular attention to SnO2/MoO3 systems, which were synthesized in various proportions by weight of molybdenum oxide, using the impregnation technique By wet method, aiming to obtain materials with high industrial applicability. The catalysts were characterized using various techniques, including, thermogravimetric analysis (TG/DTA), absorption spectroscopy in the infrared (FTIR) spectroscopy, Raman spectroscopy, diffraction X-ray (XRD), FTIR using pyridine as probe molecule spectroscopy Diffuse ultraviolet-visible reflectance (DRS) and fisistion analysis (BET). In addition to these techniques, the acid sites of the catalysts were measured by the aqueous method using sodium hydroxide and hydrochloric acid as the titrant. The results show that the main factor that influences the conversion of fructose are present the acid sites in the catalysts. This study shows that the molybdenum oxide obtained high fructose conversions at temperatures of 150 ° C and 190 ° C, but this does not reflect the products quantified by HPLC, with a large production of insoluble materials in the reaction medium, which are the main cause fouling of catalysts. On the other hand, tin oxide presented low activity in the conversion of fructose, but high selectivity to Hydroxymethylfurfural (HMF). In this context, the catalyst that provided good conversions and less formation of insoluble materials was SnMo25, being HMF selective. On the other hand, SnMo50 and SnMo75 provided high selectivity to lactic acid, but with the inconvenience of formation of insoluble products in appreciable quantity. The impregnation was an effective strategy for the formation of new sites and reuse leaching test and showed promising results. / Conselho Nacional de Desenvolvimento Científico e Tecnológico / O desenvolvimento de catalisadores heterogêneos, que sejam eficientes e de fácil recuperação, é um dos principais desafios tecnológicos enfrentados atualmente, atrelado às preocupações ambientais e econômicas. Assim, no presente trabalho foram estudados os sistemas catalíticos SnO2, MoO3 e SnO2/MoO3 na conversão da frutose, com especial atenção ao sistema SnO2/MoO3, os quais foram sintetizados em diversas proporções em massa de óxido de molibdênio, utilizando a técnica de impregnação por via úmida, visando obter materiais com alta aplicabilidade industrial. Os catalisadores foram caracterizados utilizando várias técnicas, nomeadamente, análise termogravimétrica (TG/DTA), espectroscopia de absorção na região do infravermelho (FTIR), espectroscopia Raman, difração de raio-x (DRX), FTIR utilizando a piridina como molécula sonda, espectroscopia de refletância difusa no ultravioleta-visível (DRS) e análises de fisissorção (BET). Além dessas técnicas, os sítios dos catalisadores foram medidos pelo método aquoso utilizando hidróxido de sódio e ácido clorídrico como agente de titulação. Os resultados mostram que o principal fator que influência a conversão da frutose são os sítios ácidos presentes nos catalisadores. Com esse estudo pode-se constatar que o óxido de molibdênio obteve altas conversões de frutose nas temperaturas de 150 °C e 190 °C, porém isso não reflete os produtos quantificados por HPLC, havendo grande produção de materiais insolúveis, que são a principal causa de incrustação dos catalisadores. Por outro lado, o óxido de estanho apresentou baixa atividade na conversão da frutose, porém alta seletividade a Hidroximetilfurfural (HMF). Nesse contexto, o catalisador que proporcionou boas conversões e menor formação de materiais insolúveis foi o SnMo25, sendo seletivo a HMF. Por outro lado, o SnMo50 e SnMo75 proporcionaram altas seletividade a ácidos orgânicos, porém com o inconveniente da formação de produtos insolúveis em quantidade apreciável. A impregnação foi uma estratégia eficiente, para a formação de novos sítios e os testes de reuso e lixiviação exibiram resultados promissores.

Elektrochemické metody nacházejí využití v mnoha aplikacích (např. senzorice, skladování el. energie nebo katalýze). Jejich nespornou výhodou je nízká finanční náročnost na přístrojové vybavení. Abychom lépe porozuměli procesům probíhajícím na elektrodách, je dobré znát elektronickou pásovou strukturu materiálu elektrody. Úkolem této práce je vyhodnotit výstupní práci a pozici hrany valenčního pásu nových materiálů pro elektrody, konkrétně cínem dopovaného oxidu india pokrytého nanotrubicemi sulfidu wolframičitého. Ultrafialová fotoelektronová spektroskopie a Kelvinova silová mikroskopie jsou metody použité pro tuto analýzu. Zvláštní důraz je kladen na přípravu vzorků elektrod pro měření, aby nedošlo k nesprávné interpretaci výsledků vlivem vnějších efektů jako je např. kontaminace nebo modifikace povrchu.

Naturgas är ett alternativ till oljebaserade bränslen. Ur ett miljöperspektiv är naturgasen fördelaktig eftersom den vid förbränning ger mindre utsläpp av miljöfarliga ämnen än olja. I en diesel dual-fuel motor används diesel och naturgas som bränsle. Naturgas består till största delen av metan. För att oskadliggöra den del av metangasen som inte förbränns i motorn krävs en avgaskatalysator som kan bryta ned det relativt stabila metanet vid låga temperaturer. Målet med det här kandidatexamensarbetet är att tillverka och testa tre olika avgaskatalysatorer för nedbrytning av metan. De tre katalysatorer som valdes för tillverkning och testning var Pd/Al2O3, Pd/SnO2 och In2O3/SnO2 (ITO). Valen baserade sig på att katalysatorerna som tillverkades skulle vara aktiva för nedbrytning av metan vid låga temperaturer. ITO sågs som en extra intressant kandidat eftersom In är billigare än ädelmetallen Pd. Pd/Al2O3 tillverkades med en kommersiell support och impregnering av Pd genom ”incipient wetness” (IW). Pd/SnO2 tillverkades på samma sätt. ITO tillverkades genom ”forward co-precipitation”. En monolit testades för varje katalysator. Vid ungefär 315 °C kunde 10 % omsättning av metan detekteras för alla tre katalysatorer. Pd/Al2O3 var den katalysator vars aktivitet förbättrades som mest då temperaturen ökade ytterligare. Katalysatorerna testades bara en gång. För att statistiskt säkerställa resultaten behöver upprepade tester göras. Resultaten överensstämmer delvis med tidigare studier. Slutsatsen av arbetet är att alla tre katalysatorer fungerar och att ITO skulle kunna vara en billigare men i övrigt likvärdig avgaskatalysator för en diesel dual-fuel lean burn motor vid 315 °C. Fler tester måste dock göras för att ta reda på om ITO verkligen är ett mer fördelaktigt alternativ.

Thin transparent conductive layers containing ATO nanoparticles are a modern material that has found use in a wide range of optoelectronic applications. For liquid phase deposition there were designed and prepared compositions using a „brick and mortar“ approach combined templating agents. A sol-gel solution formed of inorganic precursors of tin chloride and antimony trichloride in the presence of ATO nanoparticles was mixed with a surfactant to improve the structure and wettability of applied films. Polyethylene glycol, polyoxyethylene (20)cetylether, sodium dioctylsulfosuccinate and polyvinylpyrrolidone were used as templating agents. Thin layers of these compositions were applied by the spin-coating method. Characterized parameters were resistivity, thickness and turbidity. A resul compositions showed relatively good electrical properties and high transparency and a potencial to be used for material printing.