Dissertations / Theses: 'Composites Au / gC3N4 / TiO2'

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Marchal, Clément. "Synthèse et réactivité de nanocomposites Au / g-C3N4 / TiO2 pour la production d’hydrogène par procédé photocatalytique sous illumination solaire et visible." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF011/document.

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Dans le contexte actuel d’une demande énergétique croissante associée à un appauvrissement des ressources fossiles, il devient urgent de trouver des sources d’énergies alternatives, écologiquement et économiquement viables. La photocatalyse est une voie prometteuse et innovante pour produire de l’hydrogène (H2) à partir d’énergies renouvelables. Le but est de développer des matériaux stables et efficaces pour amener le procédé à un niveau de maturité suffisant pour de possibles développements à moyen terme.Cette thèse est axée sur l’élaboration et l’optimisation de nouveaux systèmes composites nanostructurés, Au / gC3N4 / TiO2, pour la production d’hydrogène par procédé photocatalytique à partir de l’eau et de l’énergie solaire. L’aspect innovant étant d’optimiser chaque composant de manière à tirer profit des avantages de chacun, puis à surmonter leurs limitations individuelles en les associant de manière intime dans des structure hiérarchisées afin d’obtenir des taux de production d’H2 compétitifs à température ambiante sous illumination solaire et visible. Une étude comparative a également été entreprise sur le photocatalyseur commercial TiO2 P25 « Evonik ® » et met en avant l’efficacité de ces nouveaux matériaux. Pour finir, les activités photocatalytiques de ces composites ont ensuite été corrélées avec leurs propriétés physico-chimiques
Nowadays, energy demand is constantly increasing while fossil ressources are dwindling and has become imperative to find new alternative energy sources. Photocatalysis is a promising and innovative way to produce hydrogen (H2) from renewable energies. The ai mis to develop stable and efficient materials in order to bring the process towards sufficient efficiency for possible mid-term developments. This thesis focuses on the development and optimization of new nanostructured composite systems, Au / gC3N4 / TiO2, for hydrogen produciton by water-splitting. The innovative aspect is to optimize every components in order to take advantages of each and then to intimately associate them in hierarchical structure for obtaining competitive rates of hydrogen production at room temperature under solar and visible illumination. A comparative study was also undertaken on commercial photocatalyst TiO2 P25 « Evonik ® » to highlight the efficiency of these new materials. Finally, photocatalytic activities of these composites were correlated with their physico-chemical properties

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Jiménez-Calvo, Pablo Isaí. "Synthèses, caractérisations et performances de matériaux à base de g-C3N4 décorés avec des nanoparticules d´Au pour des applications (photo) catalytiques." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAF012/document.

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À ce jour, l’humanité est confrontée simultanément à une crise énergétique et environnementale due principalement à deux facteurs: la croissance démographique et la dépendance aux combustibles fossiles. C'est pourquoi l'urgence d'utiliser des sources d'énergie renouvelables, comme l'énergie solaire est une, solution potentielle. A ce titre, la production d'H2 décarboné par dissociation solaire de l'eau est une voie prometteuse. Néanmoins, pour atteindre l'objectif mentionné, il faut trouver un système photocatalytique (semi-conducteurs, SCs) idéal, qui nécessite quatre caractéristiques majeures: (1) une bonne capacité d'absorption de la lumière visible (2) des positions adéquates de BV et BC des SCs par rapport aux potentiels d’oxydation de l’eau et de réduction du proton (3) une utilisation efficace des photons absorbés et charges générées et (4) une bonne stabilité dans le temps. À cette fin, cette thèse contribue à la conception et à l’optimisation de trois matériaux innovants: les composites Au/g-C3N4, Au/TiO2 (P25)-gC3N4, et Au/TiO2 (NTs)-gC3N4 dont l’activité photocatalytique a été corrélé avec les propriétés physico-chimiques pour comprendre leurs performances photocatalytiques de production d'H2 sous irradiation solaire et visible. De manière annexe, certains de ces matériaux se sont également montrés performants pour les conversions du CO. Pour mettre en évidence l'efficacité des composites préparés, des études comparatives ont été testées en utilisant des références commerciales, pertinentes et les mélanges physiques correspondant
To date, mankind is facing an energy and environmental crisis simultaneously due to mainly two factors: growth population and the dependency on fossil fuels. For this reason, the urgency of using renewables sources, e.g., solar energy, is a potential solution. For example, non-carbon based H2 production from solar light driven water photodissociation is a promising approach. Nevertheless, to target the mentioned objective, an ideal photocatalytic system (semiconductors, SCs) has to meet four main features: (1) capacity of absorption of visible-light (2) suitable VB and CB positions of SCs to undergo the two half reactions of water splitting (3) efficient use of absorbed photons and generated charges and (4) good stability over time. For this purpose, this thesis contributes to the design and optimization of three innovative materials: Au/g-C3N4, Au/TiO2 (P25)-gC3N4, and Au/TiO2 (NTs)-gC3N4 composites. Their photocatalytic activities were correlated with their physico-chemical properties. In addition some of these composites also exhibited interesting CO conversion yields. To highlight the efficiency on the as-prepared composites, comparative studies were tested using commercial, pertinent references, and physical mixtures homologs

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Paušová, Šárka. "Elaboration de matériaux composites photocatalytiquement actifs pour des applications environnementales." Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22475/document.

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Ce travail décrit la synthèse et le comportement de nouveaux photocatalyseurs à base de dioxyde de titane utilisés pour des applications environnementales. Dans la première partie, la pertinence des composés modèles testés, le colorant acide orange 7 (AO7) et le 4-Chlorophénol (4-CP), pour des traitements photocatalytiques à base de TiO2 a été étudiée et validée. Cette étude a été centrée sur l’effet de la concentration initiale en composé et sur la vitesse d’agitation pendant la réaction photocatalytique. La deuxième partie est consacrée principalement à la synthèse et la caractérisation des suspensions de particules colloïdales de TiO2. Leur séparation puis leur récupération après le traitement étant pratiquement impossible l’immobilisation de ces particules sur des supports de type hydroxydes doubles lamellaires (HDL) a été étudiée afin de préparer un matériau composite TiO2/HDL présentant une activité photocatalytique comparable à celle du dioxyde de titane pur. Un deuxième type de composite basé sur des mélanges de TiO2/SiO2 a également été envisagé et utilisé dans la préparation de fines couches efficaces pour la photodégradation de l’hexane. Enfin, le comportement photocatalytique d’HDL pur à base de zinc et de chrome, sans addition de TiO2, a également été étudié et est présenté dans la partie finale de cette thèse. Les matériaux préparés ont été caractérisés par différentes analyses chimiques, diffraction et fluorescence des rayons X, microscopie électronique à transmission et à balayage, spectroscopie IR à transformé de Fourier, analyse thermogravimétrique, mesure du potentiel Zeta, diffusion de la lumière, mesure d’adsorption N2. Les différents matériaux ont été testés photocatalytiquement via la photo-Oxydation en solution aqueuse de l’acide orange 7 (AO7), du 4-Chlorophénol (4-CP) ou du bleu de méthylène à différents pH. L’activité photocatalytique du matériau composite à base de TiO2/SiO2 sous forme de film fin a été évaluée en phase gaz en présence d’hexane
This work describes the behaviour and fabrication of new photocatalysts based on titaniumdioxide for the purpose of environmental applications. It consists of five closely connectedparts. In the first part the suitability of chosen model compounds, azo dye Acid Orange 7(AO7) and 4-Chlorophenol (4-CP), for photocatalytic activity assessment of TiO2 was studied.This study was focused on the effect of different initial concentrations of model compoundand different rates of stirring during photocatalytic reaction. The second part then focusedmainly on the synthesis and characterization of aqueous colloidal suspensions of TiO2. Theseparation of TiO2 particles in the form of colloidal suspensions and their regeneration afterthe reaction, while keeping the same photocatalytic properties, is almost not possible.Therefore, it was necessary to find an appropriate method how to immobilize these particleson the support or in the form of composite. The layered double hydroxides (LDH) werechosen as one of suitable supports for TiO2 photocatalyst. The focus was kept on thepreparation of TiO2/LDH composites with the same or higher photocatalytic activity as purecolloidal titanium dioxide. The second chosen type of composite was based on twocomponentTiO2/SiO2 material and these composites were used for the preparation of thinlayers. Photocatalytic behaviour of pure LDHs and their possible use as photocatalyst withoutTiO2 addition was also studied and described in a final part of this work. Prepared materials were characterized by chemical analysis, X-Ray diffraction andflorescence, transmition electron microscopy, scanning electron microscopy, Fouriertransform infrared spectroscopy, thermogravimetric analysis, dynamic light scattering, zetapotential measurement and N2 adsorption. As another step, materials were tested asphotocatalyst by the photooxidation of Acid Orange 7, 4-Chlorophenol and Methylene Blue indifferent pH in aqueous medium. Photocatalytic activity of TiO2/SiO2 composites in the formof thin films was tested in gaseous phase using hexane as a model pollutant. It was found that quantum yields of 4-CP degradation for all prepared alkaline colloidalsuspensions of TiO2 were lower than those obtained for acidic TiO2 colloidal suspensions. Inthe contrary to the quantum yield of acidic TiO2, the quantum yield of alkaline suspensionsdecreased during the aging. Prepared TiO2/Mg2Al1.5 nanocomposites exhibited higherphotocatalytic activity than the original TiO2 in basic conditions and also it was much easierto recover the photocatalyst after reaction by simple sedimentation. In the case of TiO2/SiO2composites, it was found that composite prepared with TiO2:SiO2 ratio 1:1 has higherphotocatalytic activity in aqueous media than starting pure TiO2 but with increasing SiO2content reaction rate of AO7 degradation decreases. Thin layers of TiO2:SiO2 compositeprepared from simultaneously co-Precipitated particles (they have improved crystallinity inrelation to pure TiO2) are able to photocatalyticaly degrade hexane. In the case of pure LDH,it was proved that even noncalcined Zn2CrCO3 LDH can produce HO• radicals. However,mixed oxides (containing ZnO) prepared by LDH calcination at temperatures higher than500°C, showed higher efficiency

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Hou, Hongmei. "Supercritically-treated TiO2-activated carbon composites for environmental cleaning." Kyoto University, 2006. http://hdl.handle.net/2433/143798.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(エネルギー科学)
甲第12424号
エネ博第131号
新制||エネ||32(附属図書館)
24260
UT51-2006-J415
京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻
(主査)教授坂志朗, 教授石原慶一, 助教授河本晴雄
学位規則第4条第1項該当

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Kwiatkowski, Maciej. "ZnO(core)/TiO2(shell) composites : influence of TiO2 microstructure, N-doping and decoration with Au nanoparticles on photocatalytic and photoelectrochemical activity." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCK046/document.

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Le but de la thèse est d'étudier l'influence de la microstructure des composites ZnO/TiO2 sur leurs propriétés dans la dégradation photocatalytique des polluants organiques et dans l'oxydation de l'eau photoassistée. Pour réaliser cette étude, nous avons choisi la conception basée sur des nano bâtonnets ZnO supportés sur une électrode de verre recouverte d'ITO (Indium Tin Oxide). Les nano bâtonnets de ZnO ont ensuite été recouverts d'une couche de TiO2 dans différentes conditions. La composition et la microstructure des composites ZnO(cœur)/TiO2(coquille) ont été modifiées dans le but d'élucider comment ces paramètres influencent leur activité photocatalytique. La couche TiO2 de morphologie différente (discontinue ou compacte) a été élaborée. Nous avons montré que le composite contenant la couche de TiO2 discontinue possède une activité plus élevée dans la dégradation de MB et dans l'oxydation de H2O sous 400 nm. Cette photoactivité améliorée a été attribuée à une meilleure accessibilité pour les réactifs de l'interface ZnO/TiO2 à travers la couche de TiO2. Aussi nous avons pu améliorer l'activité des composites sous la lumière visible. Dans ce but, les composites constitués de nano bâtonnets de ZnO supportés sur ITO ont été recouverts de TiO2 dopé à l'azote et décorés de nanoparticules d'or. Il a été trouvé que même une faible charge d'or (0,37% at.) permet une augmentation de 60% de la vitesse de décoloration photocatalytique du MB sous la lumière visible par rapport à l'échantillon sans or en raison de l'effet plasmonique. Un dopage simultané à l'azote et à l'or a permis également de multiplier par trois le photocourant dans l'oxydation photoassistée de l'eau
The aim of the thesis is to study the influence of microstructure of ZnO/TiO2 composites on their properties in photocatalytic degradation of organic pollutants, and in photoassisted water oxidation. To realize such study we chose the design based on ZnO nanorods supported on ITO (Indium Tin Oxide)-coated glass electrode. The ZnO nanorods were then covered with a layer of TiO2 under different conditions. The composition and microstructure of the obtained ZnO(core)/TiO2(shell) composites were modified in the aim to elucidate how these parameters influence their photocatalytic activity. The results of studies lead to elaboration of two most distinctive variants of sol-gel procedure that allow to deposit TiO2 layers of controlled thicknesses and different morphology (rugged or compact). The composite containing the rugged TiO2 layer was shown to possess significantly higher activity in MB degradation and in photoassisted H2O oxidation under 400 nm. This improved photoactivity was attributed to a higher porosity and better accessibility of ZnO/TiO2 interface region through the rugged TiO2 layer by the reagents. The effort was also made to enhance the visible light activity of the composites. To this aim the composites consisting of ITO-supported ZnO nanorods covered with nitrogen-doped titanium dioxide and decorated with Au nanoparticles. It was found that even a low Au loading (0.37% at.) resulted in 60% enhancement of photocatalytic decolorization of MB under visible light with respect to the Au-free sample owing to plasmonic effects. A simultaneous N-doping and Au decoration allowed also to multiply by three the photocurrent in photoassited water oxidation

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Ishchenko, Olga. "Elaboration of plasmonic nano-composites and study of their specific catalytic activities." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAF042/document.

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L’objective est d’améliorer l’activité photocatalytique de TiO2 sous irradiations UV et Visible. Pour contourner les limites de TiO2 intrinsèque nous envisageons une fabrication de nanocomposite plasmonique à base de nanofils de TiO2 périodiquement organisés et assemblés avec des nanoparticules plasmoniques. Pour la fabrication des nanofils de TiO2 mécaniquement stables, deux approches ont été réalisées. La première approche est basée sur la croissance sélective en phase vapeur, la deuxième approche consiste en l’utilisation d’un moule de membranes AAO et d’un dépôt de films conformes par ALD. En parallèle les films de TiO2déposés par ALD sont assemblés avec les nanoparticules plasmoniques d’or. Les différentes architectures de TiO2 sont valorisées par des tests photocatalytiques (UV et Visible) sur les polluants modèles. Une nouvelle approche de la fabrication des films mesoporeux d’H-TiO2 avec efficacité photocatalytique à la fois sous irradiation UV et Visible est développée
The objective of this thesis is to improve the photo-response of well-known photocatalytic material such as TiO2, which is usually only active in the UV range. The basic idea is to assemble several approaches within one device to improve the photocatalytic properties: fabrication of periodically-organised TiO2 nanostructures and their assembly with plasmonic nanoparticles. Two fabrication strategies were investigated for these purposes. The first approach consists of selective vapour phase growth. The second approach implements the use of an AAO template. In parallel, TiO2 films deposited by ALD and assembled with plasmonic gold nanoparticles are investigated. The photocatalytic measurements on various TiO2 architectures were performed in both irradiation ranges UV and Vis. A new fabrication approach of mesoporous H-TiO2 films was developed giving promising results of photocatalytic efficiency improvement in both UV and Visible ranges

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Tran, Duc Trung. "Elaboration et mise en œuvre de membranes composites polymère-TiO2 faiblement colmatantes." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTG023.

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Cette thèse porte sur l’élaboration et l’étude des performances de membranes d’ultrafiltration PVDF-TiO2 possédant des propriétés anti-colmatantes et photo-induites. La membrane est obtenue par application de la méthode de séparation de phases induite par un non-solvant sur un collodion de polyfuorure de vinylidène au sein duquel ont été incorporées des nanoparticules de TiO2. Il est montré : i) que la presence des nanoparticules de TiO2 les propriétés membranaires, et notamment le flux de perméat, par rapport à la membrane PVDF ; ii) que l’augmentation de la température de préparation de la membrane permettait de modifier la structure membranaire, en passant d’une morphologie constituée principalement de macrovides (dite en “doigts de gants”) à des températures basses à une morphologie spongieuse, contenant des pores de plus petite taille, à température élevée. Au-delà de la structure membranaire, des propriétés telles que la perméabilité, la porosité, la résistance mécanique, la cristallinité et les propriétés thermiques sont également influences par les changements de température de formation. Lorsque les membranes PVDF-TiO2 sont mises en oeuvre en mode photo-filtration (c.-à-d. filtration avec irradiation ultraviolette (UV) continue sur la membrane), le flux à l’eau pure de la membrane PVDF-TiO2 est encore augmenté, du fait du phénomène d’hydrophilicité photo-induite des nanoparticules de TiO2. Des premières estimations suggèrent que la photo-filtration par les membranes PVDF-TiO2 serait une économiquement rentable, car le gain en termes de filtration et qualité d’eau l’emporterait sur le cout énergétique induit par l’irradiation UV. En outre, l’efficacité de la photo-filtration a été évaluée avec des solutions d’alimentation synthétiques contenant des composés inorganiques et organiques représentatifs des eaux de surface. Il a été montré que si la plupart des ions inorganiques communément rencontrés dans l’eau potable n’ont aucun effet sur l’efficacité de la photo-filtration, la coexistence de Cu2+ et HCO3- dans l’eau d’alimentation entraîne un colmatage inorganique sévère qui inhibe le phénomène hydrophilicité photoinduite. En outre, la membrane PVDF-TiO2 présente également des flux plus élevés et une activité photocatalytique lors de la photo-filtration de solutions contenant des matières colmatantes organiques comme les acides humiques ou l’alginate de sodium. En conclusion, la membrane composite PVDF-TiO2 a démontré des propriétés et des performances significativement améliorées par rapport à la membrane PVDF, a fortioti lorsqu’elle est mise en oeuvre dans un système de photo-filtration sous irradiation UV. Ainsi, ce sont des matériaux prometteurs pour des applications membranaires en traitement de l’eau
This thesis deals with the elaboration and performance of a specific type of ultrafiltration membrane with anti-fouling and photo-induced properties, the PVDF-TiO2 composite membrane. The membrane was fabricated via the nonsolvent-induced phase separation method by incorporating titanium dioxide (TiO2) nanoparticles into the polyvinylidene fluoride (PVDF) polymer matrix. The TiO2 nanoparticles played a significant role in facilitating the membrane formation process and improving the composite membrane properties compared to the neat PVDF membrane. It was demonstrated that, by changing the membrane preparation temperature, the membrane structure could be affected dramatically, notably the morphological dominance of finger-like macrovoids at lower temperatures and their diminution in both size and number when temperature increased. Other membrane properties also saw systematic transitions with changes in formation temperature, as characterized by permeability, porosity, mechanical strength, crystallinity, and thermal properties. In terms of performance, the PVDF-TiO2 membrane exhibited superior permeate flux compared to the neat PVDF membrane. More importantly, when being operated in photo-filtration mode (i.e. filtration with continuous ultraviolet (UV) irradiation on the membrane), the pure water flux of PVDF-TiO2 membrane could be further increased, thanks to the enhanced hydrophilicity of the membrane, which comes from the photo-induced hydrophilicity phenomenon of TiO2. Preliminary estimations suggest that photo-filtration is a cost-effective method, as the benefit from enhanced water output outweighs the extra energy demand for UV irradiation. Furthermore, the efficiency of photo-filtration was evaluated with synthetic feed solutions containing inorganic and organic contents representative in surface water. It was identified that, while most of the common inorganic ions in drinking water had no effects on photo-filtration efficiency, the coexistence of Cu2+ and HCO3- in the feed led to severe inorganic fouling and inhibited the photo-induced hydrophilicity phenomenon. Besides, the PVDF-TiO2 membrane also showed its stronger flux performance and photocatalytic activity during photo-filtration of solutions containing organic foulants like humic acids or sodium alginate. In conclusion, the PVDF-TiO2 composite membrane exhibited much improved properties and performance compared to the neat PVDF membrane, and even stronger performance when operated in photo-filtration mode. Thus, it is a promising candidate to be used in membrane-based applications for water treatment

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Balayeva, Narmina [Verfasser]. "Visible-light-driven photocatalytic organic synthesis with surface modified TiO2-composites / Narmina Balayeva." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2020. http://d-nb.info/1216240957/34.

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Balayeva, Narmina Oktay [Verfasser]. "Visible-light-driven photocatalytic organic synthesis with surface modified TiO2-composites / Narmina Balayeva." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2020. http://d-nb.info/1216240957/34.

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SANUSI, IBRAHIM J. "Synthesis, Characterization, and Analysis of TiO2/ZnO Composites Thin Films Photocatalysts for Ethanol Vapor Oxidation." Miami University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=miami1626637854831713.

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Holtzinger, Claire. "Effets de composition et de morphologie sur la mouillabilité de revêtements sol-gel nanocomposites." Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00961171.

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Des revêtements sol-gel nanocomposites TiO2-SiO2 ont été réalisés à partir de mélanges d'une suspension nanocristalline de TiO2 anatase et de sols polymériques de silice. Ces revêtements présentent une superhydrophilie naturelle, persistante et photo-régénérable. La présence de charges localisées aux interfaces granulaires TiO2-SiO2 est une des hypothèses permettant d'expliquer cette superhydrophilie naturelle. Toutefois des effets de morphologie (rugosité, porosité de surface) sont également connus pour influencer le mouillage. Des études ont été menées pour mettre directement en évidence l'effet intrinsèque des interfaces granulaires. Les études se sont recentrées sur l'effet extrinsèque de paramètres morphologiques susceptibles d'influencer la mouillabilité des revêtements nanocomposites selon des modèles thermodynamiques des surfaces connus. De nouveaux protocoles de synthèse par voie sol-gel ont été mis au point afin d'analyser i/ en quoi la superhydrophilie naturelle et photo-induite des revêtements TiO2-SiO2 pouvait être influencée par des effets de morphologie et de composition, et ii/ en quoi une exacerbation de ces effets via des structurations artificielles pouvaient encore accroître la superhydrophile de surface. Une extrapolation de ces protocoles a également permis d'étudier des revêtements superhydrophobes.

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Joshi, Sharmad Vinod. "Characterization of 3D printed metal oxide composite polymers." Miami University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=miami1595511295182678.

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Karabulut, Meryem. "The Effect Of Inorganic Composites On The Thermal Degradation Of Polymethylmetacrylate (pmma)." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613752/index.pdf.

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Metal coordinated polymer nanocomposites have gained great attention due to their superior characteristics. Polymethylmethacyrlate (PMMA) is the most commonly used polymer since it is easily processed. In this study, modified TiO2 nanoparticles prepared by insitu and exsitu methods were embedded into PMMA in order to improve its thermal stability and the effects of TiO2 nanoparticles on thermal characteristics of PMMA were investigated by direct pyrolysis mass spectrometry. The insitu method which is a sol gel method, TiO2/SiO2 nanoparticles were synthesized by mixing titanium(IV) tetraisopropoxide, TTIP, with silane coupling agent, 3-(3-methoxysilyl)methylmetacrylate, MSMA in absolute ethanol. In exsitu method, TiO2 powder was directly mixed with silane coupling reagent. TiO2/SiO2 nanoparticles were embedded into the PMMA by direct mixing resulting in exsitu and insitu TiO2/SiO2/PMMA nanocomposites. The synthesized TiO2/SiO2/PMMA nanocomposites were characterized by TEM, ATR-FT-IR and analyzed for the investigation of their reaction mechanism and thermal characteristics by pyrolysis mass spectroscopy. iv TEM images confirmed the formation of TiO2/SiO2 nanoparticles and TiO2/SiO2/PMMA nanocomposites and indicated that the average particle size of TiO2/SiO2 nanoparticles was around 6 nm whereas average particle size of SiO2/TiO2/PMMA nanocomposites were around 25 nm. The increase in the size of nanoparticles is associated with incorporation of TiO2/SiO2 nanoparticles into PMMA matrix. ATR-FTIR spectrum of 5% TiO2/SiO2/PMMA nanocomposites showed the formation of TiO2/SiO2 nanopartciles clearly. Pyrolysis mass spectrometry analysis revealed that incorporation of TiO2/SiO2 nano- particles into PMMA resulted in higher thermal stability only for low weight percentage insitu TiO2/SiO2/PMMA. At high weight percentages a decrease in thermal stability was detected. On the other hand, in case of exsitu TiO2/SiO2/PMMA, contrary to our expectations a decrease in thermal stability was detected. The decrease in thermal stability was attributed to evolution of methacrylic acid during thermal degradation of silane groups.

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Mertz, Grégory. "Evolution des propriétés physico-chimiques et mécaniques de composites à base caoutchoucs lors du photo-vieillissement." Thesis, Vandoeuvre-les-Nancy, INPL, 2011. http://www.theses.fr/2011INPL074N/document.

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Les caoutchoucs, ou plus généralement, les polymères subissent de façon néfaste les agressions du milieu environnant au cours de leur utilisation. Deux facteurs sont connus comme étant parmi les plus importants impliqués lors du vieillissement : l’oxygène atmosphérique et les rayonnements UV-visibles solaire, conduisant au phénomène de photo-oxydation. Sachant que le vieillissement dans ce cas est régi par la pénétration de la lumière et la diffusion de l’oxygène, il y a au cours de l’irradiation formation d’une couche d’oxydation sur les premiers microns de la surface du matériau. L’objectif majeur de cette thèse est de mettre en évidence un lien entre l’évolution de la structure chimique et la perte des propriétés mécaniques dans le cadre de matériaux vulcanisés au cours du photo-vieillissement, en présence de charges telles que le dioxyde de titane et un colorant organique, au moyen d’une approche multi-techniques et multi-échelles.Afin d’y parvenir nous avons tout d’abord simplifié le matériau vulcanisé et nous nous sommes focalisés sur la matrice et les charges. Cette première étape nous a permis de déterminer l’influence des charges sur les mécanismes de photo-oxydation des caoutchoucs non vulcanisés, et nous a servi de base à la compréhension des matériaux vulcanisés plus complexes.Dans la deuxième étude, la caractérisation physico-chimique de la couche dégradée formée au cours de l’irradiation des composites vulcanisés a été effectuée. Nous avons par la suite confronté ces résultats avec la chute des propriétés mécaniques observée au cours du vieillissement. Nous avons ainsi mis en évidence une corrélation directe entre la structure chimique liée aux propriétés de la couche oxydée et la chute des propriétés mécaniques
Rubbers or mostly polymers are exposed to different attacks from the surroundings during their uses. Two factors are known to be among the most important involved during aging: atmospheric oxygen and UV-visible radiation from the sun, leading to the phenomenon of photo-oxidation. Photo-ageing is governed by the light penetration and diffusion of oxygen, which involve the formation of an oxidative layer on the first microns at the surface of the material. The main objective of this thesis is to point out the relationship between the changes in the chemical structure due to the formation of the oxidative layer and the loss of mechanical properties during photo-aging of vulcanised rubber in the presence of fillers such as titanium dioxide and organic dye by means of a multi-techniques and multi-scale approach.To achieve this goal, we first simplified the vulcanized material and we focused only on the matrix and fillers. This first step allowed us to determine the influence of fillers on the mechanisms of photo-oxidation of unvulcanised rubber. This study helped to better understand more complex materials such as vulcanised rubbers. In the second study, we focused on the physic-chemical characterization of the degraded layer formed during irradiation of vulcanised rubber. After that, we compared the results with the loss of the mechanical properties observed during aging. This study highlighted a link between the changes of the chemical structure related to the properties of the oxidized layer and the loss of the mechanical properties

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Ribeiro, Enrique. "Composites Charbon-Actif/TiO2 pour des applications solaires Activated-Carbon/TiO2 composites preparation: An original grafting by milling approach for solar water treatment applications TiO2 grafted Activated Carbon elaboration by milling: composition effect on sorption and photocatalytic properties Experimental and theoretical coupled approaches for the analysis of radiative transfer in photoreactors containing particulate media : case study of TiO2 powders for photocatalytic reactions AC/TiO2 granular photocatalysts optical properties : material composition effect on the radiative transfer in a photoreactor." Thesis, Perpignan, 2020. http://www.theses.fr/2020PERP0016.

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L'utilisation de composites possédant une double fonctionnalité adsorption/photo-oxydation est une solution d'intérêt majeur pour traiter les polluants bio-récalcitrants contenus dans les eaux usées, par voie à partir d’énergie solaire. Cette étude propose la mise en œuvre de composites associant charbon actif (CA) et dioxyde de titane (TiO2) par une méthode originale de préparation, la mécanosynthèse. La faisabilité de la préparation de composites CA/TiO2 par mécanosynthèse a d'abord fait l'objet d'un travail d'investigation permettant sa validation. Cette première étape a permis de montrer la pertinence de la méthode pour l'élaboration de composites CA/TiO2 sous forme pulvérulente qui ont des propriétés structurales homogènes et maîtrisées et possèdent les propriétés fonctionnelles de photo-oxydation et de sorption recherchées. Dans un second temps, ces travaux montrent l'adaptabilité de la méthode pour la fabrication de composites CA/TiO2 de composition et donc de propriétés modulables en fonction de l'application de traitement de l'eau ciblée. Les propriétés radiatives de ces matériaux – qu'il est primordial de connaître pour envisager leur intégration au sein d'un photoréacteur – ont été déterminées par une approche théorique couplée à des mesures expérimentales. Il a ainsi pu être possible dans un dernier temps de modéliser et de simuler le transfert radiatif au sein d'un photoréacteur de géométrie simple contenant ces matériaux
The use of bifunctional adsorbent/photocatalyst composite is a solution of great interest for the solar removal of persistent pollutants from wastewaters. This work investigates the mechanosynthesis as an original approach for the preparation of Activated-Carbon/TiO2 composites . First, the feasibility of the preparation approach was validated. The method appeared relevant to produce homogeneous AC/TiO2 granular composites with controlled structural properties. The control of the preparation parameters led to both AC and TiO2 sorption and photo-oxidation functional properties preservation within the composite structure. Secondly, the preparation method ability in creating compositionally-varied AC/TiO2 composites, exhibiting different functional properties. This second part allowed us to show the adaptability of the AC/TiO2 preparation for a wide range of water treatment applications. The radiative properties of these materials - which are essential to know in order to consider their integration within a photoreactor - have been determined by a theoretical approach coupled with experimental measurements. It was thus possible to model and simulate the radiative transfer within a simple geometry photoreactor containing these materials

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Parala, Harish. "Precursor routes to selected metal and semiconductor nanomaterials crystals, composites, colloids of Au, GaN, InN, CdSe and TiO2 /." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=96870901X.

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17

Barlier, Vincent. "Composites pour la conversion photovoltaïque élaborés par génération in situ de TiO2 en film mince de Poly (N-vinylcarbazole)." Lyon 1, 2008. http://www.theses.fr/2008LYO10036.

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Le travail présenté dans ce mémoire de thèse porte sur la réalisation de couches minces composites TiO2 :poly(N-vinylcarbazole) (PVK) et sur leur utilisation comme système accepteur:donneur d’électrons dans des diodes photovoltaïques. Des couches minces TiO2 :PVK, obtenus à partir d’une solution de polymère dans laquelle est dispersée des nanoparticules de TiO2, ont tout d’abord été étudiés montrant les limites de la nanostructuration par ce procédé traditionnel d’élaboration. Une voie originale fut alors explorée consistant à utiliser des alkoxydes de titane en remplacement des particules de TiO2 afin de générer in situ, par réactions d’hydrolyse-condensation, une phase de TiO2 mixée à l’échelle nanométrique avec le polymère. Afin d’améliorer la miscibilité entre la phase organique et la phase inorganique, un nouveau précurseur de TiO2 possédant une structure moléculaire proche du motif répétitif du polymère a été synthétisé : le tétrakis (9H-carbazole-9-yl-ethyl-oxy) de titane. Ce nouveau matériau a permis l’élaboration de réseaux interpénétrés TiO2:PVK possédant une meilleure nanostructuration qu’avec un alkoxyde de titane usuel comme l’isopropoxyde de titane. L’influence de la nature des ligands sur la réactivité du précurseur de TiO2 ainsi que sur les propriétés photoélectriques fut alors discutée, montrant l’étroite interdépendance entre la morphologie des couches minces et les propriétés photovoltaïques des cellules
This study focuses on the elaboration of TiO2:poly(N-vinylcarbazole) (PVK) thin films and on their applications as acceptor:donor systems in photovoltaic devices. First, thin films elaborated from a dispersion of TiO2 nanoparticles in a solution of PVK were studied highlighting the limits of this route on the nanostructuration. Then an original approach based on in situ generation of TiO2 in polymer thin film from hydrolysis-condensation reactions of titanium alkoxide was investigated. To increase the miscibility between organic and inorganic phases, a new synthesized TiO2 precursor bearing ligands close to the repetitive units of the polymer was used: titanium tetrakis (9H-carbazole-9-yl-ethyl-oxy). This new TiO2 precursor allows obtaining TiO2:PVK interpenetrating network more homogeneously mixed than those elaborated from a more classical TiO2 precursor as titanium isopropoxide. Influence of the nature of ligands was discussed as well on the reactivity of titanium alkoxides as the photoelectric properties of the photovoltaic devices

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Daniel, Alain. "Revêtements minces Zn-Si-O et Ti-Si-O : élaboration au moyen d'un procédé plasma hybride pulvérisation cathodique-PECVD et caractérisation." Thesis, Vandoeuvre-les-Nancy, INPL, 2006. http://www.theses.fr/2006INPL087N/document.

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Ce travail s’intéresse à la synthèse de films minces composites Zn-Si-O et Ti-Si-O à l’aide d’un procédé hybride combinant le dépôt de silice par PECVD (Plasma Enhanced Chemical Vapour Deposition) à partir du précurseur organométallique hexaméthyldisiloxane (HMDSO-Si2C6H180), et la pulvérisation réactive de zinc ou de titane. L’élaboration de revêtements dont la composition s’échelonne d’un oxyde métallique ZnOx ou TiOx à la silice est rendue possible en agissant sur le débit du précurseur. L’ajout de silicium dans le revêtement fait évoluer sa morphologie de colonnaire à dense. De plus un phénomène de compétition entre les composantes PECVD et pulvérisation du procédé est mis en évidence. Ainsi la mesure des vitesses de dépôt en fonction du débit d’HMDSO permet de déterminer les valeurs de débits critiques de précurseurs à partir desquelles le dépôt de silice par PECVD est initié, et pour lesquelles le recouvrement de la cible par le dépôt de silice se produit. Les caractérisations des revêtements montrent que ceux-ci sont constitués, dans une zone proche de l’interface avec l’acier d’un mélange d’oxydes non stoechiométriques qui diffère de manière importante d’un mélange ZnO+SiO2 ou TiO2+SiO2. Pour les revêtements de type Ti-Si-O le titane est en excès dans la zone proche de l’interface tandis que dans les revêtements de type Zn-Si-O le silicium est en excès. On observe alors une décroissance progressive de la concentration atomique respectivement de titane et de silicium lorsqu’on approche de la surface du revêtement. Ces évolutions peuvent être reliées à un effet de l’augmentation de la température dans la première phase de l’élaboration, qui agit sur la cinétique de dépôt par PECVD et conditionne l’état de contamination de la cible
The present work deals with the synthesis of Zn-Si-O and Ti-Si-O composite thin films by a hybrid process. The coatings are prepared by combining PECVD (Plasma Enhanced Chemical Vapour Deposition) of silicon oxide from hexamethyldisiloxane (HMDSO-Si2C6H180) and reactive sputtering of a zinc or a titanium target. Any composition of the deposited layer can be obtained from zinc oxide or titanium oxide to silicon oxide, by controlling the HMDSO flow rate in the reactor. The morphologies evolve from columnar to dense by adding silicon in the coating. Moreover, a competitive deposition process takes place between PECVD and sputtering. The critical flow rates above which the PECVD silicon oxide deposition takes place on the substrate and on the target can be described from measurements of the thin film deposition rates as a function of the HMDSO flow rate. The coating caracterisations show that they are, near the coating-substrate interface, made of a mixture of non-stoechiometric oxides whose composition is different from a ZnO+SiO2 or a TiO2+SiO2 mixing. Titanium and silicon are in excess near the coating-substrate interface, respectively in the Ti-Si-O and Zn-Si-O thin films. Then the atomic concentrations of titanium and silicon progressively decrease when reaching the surface of the thin film. These behaviours are correlated with an increase of the temperature during the first phase of deposition that increases the PECVD deposition kinetics and determines the contamination state of the target

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Lumbala, Jenny Chansa. "Synthesis and characterisation of Au/TiO2 composites for plasmon-enhanced visible light driven photocatalytic degradation of reactive orange 16 dye." Thesis, Cape Peninsula University of Technology, 2019. http://hdl.handle.net/20.500.11838/2984.

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Thesis (Master of Applied Science in Chemistry)--Cape Peninsula University of Technology, 2019
Photocatalysis is one of the methods that have gained popularity for degradation of organic pollutants in water. Metal oxides, such as ZnO, Fe2O3, and TiO2 are considered to be good and efficient photocatalysts. TiO2, in particular, has been the most investigated because it is naturally abundant, non-toxic and stable. However, the wide band gap of TiO2 (3.2 eV), make TiO2 only to absorb UV light. For this reason, plasmon enhanced-photocatalysis has emerged as one of the appealing processes to achieve visible light utilization by TiO2. This process exploits the Localized Surface Plasmon Resonance (LSPR) of the metal nanoparticles such as gold to harvest the visible light and bring about photocatalytic process. LSPR is the effect of the oscillation of electrons in noble metals when they are in contact with light. Due to the LSPR phenomena, noble metals are able to increase the lifetime of the charge carriers and increase electron/hole generation semiconductors photocatalysts under visible light. In this study, TiO2 was coupled with gold nanoparticles in order to facilitate visible light absorption and to improve the photocatalytic performance. Gold nanoparticles (nanospheres and nanorods) were synthesised using the Turkivich and seed mediated methods. These were characterised by UV-visible spectrophotometry, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) for optical properties, size and morphology. The concentration of the as prepared gold samples was measured using the inductively coupled plasma optical emission spectrometry (ICP-OES). Gold nanospheres and gold nanorods were loaded into TiO2 using the nucleation and growth method to obtain the Au/TiO2 plasmonic composites. To investigate to effect of the gold size, two AuNRs samples with different aspect ratios (1.9 and 3.4) were prepared and used to form the nanocomposites with TiO2. Another Au/TiO2 composite sample was prepared by loading AuNS to compare the behaviour of the two shapes. The characterisation results of these samples from the transmission electron microscopy TEM and SEM confirmed the expected shapes (spheres and rods) and the formation of the nanocomposites. The energy dispersive spectroscopy (EDS) results showed the presence of the all the expected elements in the composites materials, further confirming the successful synthesis of the Au/TiO2 composites. The absorption spectra of the prepared nanocomposites showed the plasmonic peaks of the gold nanoparticles in the visible region, which also confirmed the formation of the composite materials. The photocatalytic performance of the photocatalysts was investigated for the degradation of reactive orange 16. From the results obtained in this study, it was found that the photocatalysts loaded with AuNRs gave higher photodegradation efficiencies compared to the one loaded with AuNS. The photocatalytic efficiency was found to increase with an increase on the aspect ratio of the AuNRs. For AuNRs (1.9) the achieved efficiency was 84.56 % and 86.65 % for AuNRs (3.4). Meanwhile, direct photolysis did not have an effect on the photodegradation of Reactive Orange 16 (RO 16). The combined effect of AuNRs and AuNS showed a drastic improvement on the photocatalytic efficiency and the rates of the process which was attributed to the synergistic effects of the transverse and the longitudinal plasmons peaks of both nanospheres and nanorods. The photocatalyst prepared with the mixed nanospheres and nanorods gave an efficiency of up to 90.15 % for the 1:1 ratio at 60 min reaction time. A number of reaction parameters were investigated for their effect on the photodegradation efficiency including: pH, Au content, and temperature. The photocatalytic degradation of RO 16 was very slow in very acidic (pH 2.5) and very basic conditions (pH 11.5). The highest degradation efficiency was achieved at pH of about 6.7. Furthermore, the rate of degradation also increased with an increase in temperature from 15 oC to 30 oC due to the reduction of the activation energy. The increase in Au loading from 0.1 wt % to 0.2 wt % increased the photocatalytic performance of the catalyst from 56.29 % to 86.65 %. However, further increase in gold loading blocked the light penetration and hence, caused a decrease on the efficiency to 66.35 %.

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Telegang, Chekem Cedric. "Matériaux carbonés multifonctionnels à porosité contrôlée à partir des ressources végétales tropicales : application au traitement de l'eau par photocatalyse." Thesis, Perpignan, 2017. http://www.theses.fr/2017PERP0026/document.

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La double fonction absorption-photodégradation des composites CA-TiO2 vis-à-vis des polluants biorécalcitrants est une alternative prometteuse pour le traitement de l’eau par voie solaire. Dans ce travail, des composites CA-TiO2 sont élaborés suivants trois méthodes simples basées sur l’utilisation des biomasses trouvées dans la sous région ensoleillée de l’Afrique subsaharienne. Les charbons actifs (CA) obtenus après pyrolyse des biomasses développent une structure poreuse qui se modifie ensuite en fonction de la voie de fixation des nanoparticules TiO2 (NPs-TiO2) pour l’obtention des composites. Parmi les trois vois de fixation du TiO2, l’imprégnation du CA avec le sol de NPs-TiO2 préformées conduit à des matériaux (CAT.SX) avec du TiO2 déposé de façon homogène à la « surface externe » du CA. Cette microtexture permet un meilleur couplage des propriétés adsorption-photodégradation, favorables aux performances de dépollution évaluées à l’échelle de laboratoire sur des solutions de phénol à 100 mg.L-1. Le réseau pores/surface spécifique est moins développé sur les composites obtenus par fixation in situ des NPs-TiO2 sur du CA imprégné de gel de TiO2 (CAT.GX), ou par pyrolyse directe de biomasse pré-imprégnée de NPs-TiO2 (CAT.SBX) ; ce qui explique les performances de dépollution moins élevées enregistrées pour ces deux dernières familles de catalyseurs. Les cinétiques d’élimination du polluant obtenues après plusieurs cycles successifs d’utilisation des catalyseurs CAT.SX ont été correctement simulées avec un modèle dont le formalisme tient compte de la double fonctionnalité des catalyseurs. Ce modèle permet d’envisager le dimensionnement d’installations solaires en condition réelle d’utilisation de ces nouveaux catalyseurs en zones fortement ensoleillée
Adsorption/photodegradation dual property of AC-TiO2 composites materials towards biorefractory pollutants is a promising issue for solar water treatment. In this work, AC-TiO2 hybrid materials have been synthesized through 03 novel routes based on the conversion of typical biomasses, abundantly found in the subsaharian African sunny areas. Biomasses pyrolysis derived activated carbon (AC) developed a porous structure which is modified differently according to the method used to fix TiO2 nanoparticules (TiO2-NPs). AC impregnated with a sol containing TiO2-NPs suspension provides the derived composite material (CAT.SX) with TiO2-NPs regularly deposited at the “external surface”, leading to a good coupling of adsorption/photodegradation activities towards phenol elimination in 100 mg.L-1 polluted water, carried out on lab scale experiments. Pore/surface area network is less developed on composites obtained after in situ fixation of TiO2-NPs on TiO2 gel impregnated AC (CAT.GX), or obtained after direct pyrolysis of TiO2-NPs impregnated biomass (CAT.SBX) – which infers lesser decontamination performances for these two latter families of catalysts. Pollutant elimination kinetics curves depicted after recycling of CAT.SX over several running water treatment was simulated with a suitable mathematical model which takes into consideration the dual functionalities of the elaborated material. The established model is a promising attempt for future dimensioning of real solar water treatment plants, operating in sunny areas with the new composite catalysts

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Bonne, Magali. "Optimisation de la synthèse de matériaux poreux de haute surface, composés d'oxydes simples (SiO2, TiO2, Al2O3) et d'oxydes mixtes (perovskites), pour des applications en catalyse hétérogène." Poitiers, 2010. http://theses.edel.univ-poitiers.fr/theses/2010/Bonne-Magali/2010-Bonne-Magali-These.pdf.

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Le sujet du Doctorat porte sur l'utilisation des voies de synthèse par mésostructuration pour la préparation de supports de catalyseurs poreux. Trois systèmes ont été abordés pendant la durée du Doctorat, mais l'objectif restait le même dans les trois cas puisqu'il s'agissait de contrôler la morphologie du support afin de permettre par la suite l'optimisation du catalyseur final. La première partie du travail a été consacrée à l'étude de la synthèse d'oxydes mixtes en milieu confiné (i. E. Dans la porosité d’un support hôte). Des composés de type pérovskite (ABO3, avec A le lanthane et B un métal de transition) ont été préparés et dispersés sur différents supports siliciques de textures différentes. L'approche adoptée pour la synthèse, une méthode originale d'autocombustion développée dans le cadre du Doctorat, a permis d'obtenir des nanoparticules d'oxyde mixte de taille restreinte (< 4 nm), dispersées de manière homogène dans la porosité du support hôte. De telles tailles sont rarement rapportées pour des oxydes mixtes de ce type. Des tailles de domaine cristallin de l'ordre de 15-30 nm pour ce type d'oxyde mixte sont généralement observées. Bien que l'étude de l'activité de ces solides n'ait pas été abordée dans le cadre de ce travail, la mobilité de l'oxygène dans ces matériaux est largement supérieure à celle mesurée pour des pérovskites massiques ce qui montre clairement que ces nanocristaux se comportent différemment des cristaux massiques. Dans une deuxième partie, la synthèse, les propriétés texturales et structurales, ainsi que l'activité de nanocomposites SiO2 – TiO2 sont présentés. Par dépôt contrôlé d'un précurseur organique de titane, il est possible d'obtenir des nanocristaux d'anatase accessibles dans la porosité d'un support mésoporeux. Le mode de synthèse utilisé permet de déposer des quantités élevées d'oxyde de titane (jusqu’à 55 %pds), sans obstruer la porosité du support ni altérer les propriétés physiques du composite final qui présente toujours une surface spécifique élevée. Le maintien de propriétés attractives peut être attribué à la taille limitée des particules de titane générées, qui est généralement de l'ordre de 4 nm ou moins. Comme dans le cas de pérovskites, ces nanoparticules présentent une mobilité d'oxygène élevée, et des tests de réactivité ont montré que le contrôle de la taille de particule permettait une modulation de l'interaction métal – support (effet SMSI) lorsqu'un métal noble était déposé à sa surface. La dernière partie du Doctorat portait sur la synthèse d'alumine, une autre phase importante pour la catalyse hétérogène. Différentes voies de synthèses par mésostructuration ont été abordées, ce qui a permis de mettre en évidence l'intérêt de ces procédures pour l'obtention de solides présentant des surfaces spécifiques élevées et des tailles de pores élevées. Des résultats préliminaires ont aussi montré la flexibilité de ces voies de synthèse pour la fonctionnalisation de la surface de l'alumine (par incorporation d'un métal de transition ou d’un métal noble lors de la synthèse)
First of all the study of the synthesis of mixed oxides of ABO, perovskite in the pores of a silica host is studied. A novel method of autoignition developed within the PhD has yielded mixed oxide nanoparticles of small size (<4 nm) homogeneously dispersed in the pores of the support while sizes of the order of 15-30 nm for this type of mixed oxide are generally observed. The mobility of oxygen in these materials is much higher than that measured for bulk perovskites. In second part, the synthesis, structural and textural properties, and the activity of SiO2-TiO2 nanocomposites are presented. Anatase nanocrystals of 4 nm or less, accessible in the pores of a mesoporous support are obtained. High amounts of titania were deposited without clogging the pores of the support or alter the physical properties of the final composite. These nanoparticles exhibit high oxygen mobility. Reactivity tests showed that control of particle size allowed to adjust the metal – support interaction (effect SMSI) where the noble metal was deposited on its surface. The last part of the PhD was on the synthesis of alumina by different routes of mesostructuration. The interest of these procedures of obtaining solids with high surface area and large pores has been shown. Preliminary results also showed the flexibility of these synthetic routes for the functionalization of the surface of alumina by incorporation of a noble metal of transition metal during synthesis

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Spirandeli, Bruno Roberto. "Influência da adição de NbC e Al2O3+TiO2 nos desempenhos de revestimentos a base de Ni-Al produzidos por aspersão térmica." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-12032015-151858/.

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Aspersão térmica é um processo de produção de revestimentos metálicos, poliméricos, cerâmicos ou compósitos sobre superfícies previamente preparadas que objetiva na maioria das vezes a prevenção contra o desgaste e/ou corrosão e também a recuperação dimensional de superfícies desgastadas. Ligas de Ni-Al são extensivamente empregadas na aspersão térmica para reconstrução dimensional e como camada de ligação como materiais que não se ligam adequadamente à superfície a ser revestida. A baixa dureza e resistência ao desgaste (principalmente em aplicações de reconstrução dimensional) desta liga poderiam ser contornadas pela adição de partículas ou compostos de altas durezas na matéria prima em pó antes da aspersão. Neste trabalho avaliou-se a influência da adição de NbC e do composto cerâmico Al2O3+TiO2 no desempenho ao desgaste de revestimentos de Ni-Al, bem como verificou-se as alterações microestruturais, químicas, e mecânicas decorrentes. Para tanto se adicionou 25%p de NbC ou 25%p do composto Al2O3+TiO2 à liga base de Ni-Al, formando-se dois materiais compósitos: Ni-Al + NbC e Ni-Al + (Al2O3+TiO2). Utilizou-se microscópio eletrônico de varredura com EDS para caracterizar as matérias primas e os revestimentos produzidos, assim como determinar o mecanismo de desgaste nos ensaios de micro-abrasão tipo \"esfera-livre\" e \"esfera-fixa\". Mediram-se as durezas superficiais e as microdurezas das fases por meio dos ensaios Rockwell Superficial e microdureza Vickers. Avaliou-se a resistência ao desgaste por meio de ensaios de micro-abrasão nas modalidades \"esfera-livre\" e \"esfera-fixa\". As adições dos materiais citados na liga a base de níquel alteraram características microestruturais importantes, como aumento do percentual de óxidos, bem como a composição química e distribuição dos elementos nas camadas formadas; ocorreram também aumentos significativos das durezas e nas resistências ao desgaste dos revestimentos.
Thermo Spray is a metallic, polymeric, ceramic and composite coating process applied over a previously prepared surface usually seeking to improve wear and/or corrosion resistance. It is also used to repair worn surfaces restoring the original dimensions. Ni-Al alloys are used as a primer coating to promote the adhesion between surface and incompatible coatings and also extensively in the reconstruction of worn surfaces. The low hardness and wear resistance (when used in reconstruction applications) of this alloy could be improved by the addition of hard particles/composites to the powdered raw material prior to the spray operation. In this work the influence of NbC and Al2O3+TiO2 additions to Ni-Al alloys were evaluated concerning wear performance and the resulting changes in microstructure, chemical and mechanical behavior. The experimental procedure included the preparation of samples of the Ni-Al base alloy with additions of 25wt% of NbC or 25wt% of Al2O3+TiO2, what resulted in two different sprayed composite materials: Ni-Al + NbC e Ni-Al + (Al2O3+TiO2). SEM with EDS microprobe was used to characterize the raw materials, the sprayed coating samples and the type of wear mechanism occurring in the wear tests of the type \"free sphere\" and \"fixed sphere\" micro abrasion that were used to evaluate the wear resistance of the samples. Surface hardness and micro hardness of the different phases in the coatings were evaluated using Rockwell and Vickers micro hardness testing machines respectively. The addition of the hard phases promoted important changes in the Ni-Al base alloy, decreasing the porosity level and increasing the percentage of oxides. Hardness were significantly increased as well as the wear resistance of the coatings.

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Kazmierczak, Kamila. "Análise das propriedades do compósito de aa2014 reforçado com nanopartículas de tio2, produzido via metalurgia do pó." Universidade do Estado de Santa Catarina, 2014. http://tede.udesc.br/handle/handle/1662.

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This study evaluates the influence of processing by high energy ball milling in the production of metal matrix composite aluminum reinforced with nanoparticles of TiO2. The base AA2014 alloy was produced by mechanical alloying and subsequently strengthening was added. Several grindings were carried out by varying the ratio of nanoparticles of TiO2. After obtaining the base alloy and composite powders were subjected to annealing for the rearrangement of the microstructure and the stress relief, they were uniaxially compacted in a cylindrical die with a compressive stress of 490MPa, were subsequently extruded at a temperature of 490 °C. After extrusion materials were machined for the preparation of specimens for the tensile test, then the thermal annealing treatment occurred, was made after the heat treatment of solution-precipitation. The properties of the AA2014 alloy are influenced by the heat treatment solubilization-precipitation. The phases present and strengthening, as well as its distribution were analyzed by transmission electron microscopy, conventional optical microscopy, scanning electron microscopy (SEM). The surface of fracture of these materials was observed by SEM to evaluate the mechanism involved in the fracture. Finally, the influence of the reinforcement in the matrix was analyzed for the mechanical properties of hardness, tensile strength and sliding wear. The hardness of the material showed an increase over the base alloy. With the addition of TiO2 nanoparticles, the values obtained were very similar tribological testing. In the tensile test was observed that the composite with 1.5% TiO2 showed an increase in material strength.
Este trabalho avalia a influência do processamento por moagem de alta energia na fabricação do compósito com matriz metálica de alumínio com reforço de nanoparticulas de TiO2. A liga base AA2014 foi produzida por moagem de alta energia e posteriormente o reforço foi adicionado. Várias moagens foram realizadas, variando-se a razão de nanoparticulas de TiO2. Após a obtenção da liga base e do compósito, os pós foram submetidos a recozimento, para o reordenamento da microestrutura e para o alívio das tensões, os mesmos foram compactados em uma matriz cilíndrica uniaxial, com uma tensão de compressão de 490MPa, posteriormente foram extrudados a uma temperatura de 490°C. Após a extrusão os materiais foram usinados para a confecção dos corpos de prova para o ensaio de tração, em seguida ocorreu o tratamento térmico de recozimento, após foi feito o tratamento térmico de solução-precipitação. As propriedades da liga AA2014 são influenciadas pelo tratamento térmico de solubilização-precipitação. As fases presentes e o reforço, bem como sua distribuição foram analisadas por microscopia ótica convencional, microscopia eletrônica de varredura (MEV) e microscopia eletrônica de transmissão. A superfície da fratura destes materiais foram observadas por MEV para avaliar o mecanismo envolvido na fratura. Por fim, a influência do reforço na matriz foi analisado quanto às propriedades mecânicas de dureza, resistência à tração e ao desgaste por deslizamento. A dureza do material apresentou um aumento em relação a liga base. Com a adição das nanopartículas de TiO2, os valores obtidos no ensaio tribológico foram muito semelhantes. No ensaio de tração foi possível observar que o compósito com 1,5% de TiO2 apresentou um aumento na resistência do material.

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Morisse, Steven. "Effet du greffage de TiO2 à la surface de fibres de lin sur les propriétés mécaniques d'un composite PLA/fibre de lin longues unidirectionnelles." Mémoire, Université de Sherbrooke, 2016. http://hdl.handle.net/11143/8934.

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Les matériaux composites sont utilisés dans beaucoup de domaines pour leurs propriétés mécaniques spéciﬁques, leur mise en forme facile et leur bas coût. Cependant, lorsque les composites pétro-sourcées sont en ﬁn de vie, le traitement des déchets a un fort impact environnemental. C’est pour cette raison que les industriels se tournent vers des matériaux bio-sourcés. Ils souhaitent ainsi abaisser le coût des matières premières mais aussi se donner une image plus « verte » grâce à l’utilisation de matériaux renouvelables et/ou compostables. Le projet présenté s’inscrit dans dans cette optique où il est question d’élaborer de nouveaux composites à renfort et matrices bio-sourcés et tout particulièrement des composites ﬁbre de lin/acide polylactique (PLA). Ces derniers sont généralement appelés bio-composites. L’originalité de cette étude réside dans le traitement des ﬁbres de lin aﬁn de les compatibilité avec la matrice PLA. Le traitement consiste au greﬀage de dioxyde de titane sur la surface de ﬁbres de lin fonctionnalisée par oxydation au TEMPO. Ces ﬁbres longues sont ensuite utilisées comme renfort sous forme de tissu unidirectionnel dans la matrice PLA. Le comportement mécanique en traction, ﬂexion et la résistance à l’impact de ces biocomposites sont étudiés aﬁn d’analyser l’inﬂuence du traitement des ﬁbres sur leur performances.

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Galdino, André Gustavo de Sousa. "Produção e caracterização de arcabouços porosos de compósitos hidroxiapatita-titânia (HA-TiO2) para uso em engenharia tecidual óssea." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263456.

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Orientador: Cecília Amélia de Carvalho Zavaglia
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: À medida que há uma melhoria na tecnologia aplicada à saúde humana, a expectativa de vida vem aumentando, mas nem todas as partes do corpo podem manter suas funções com o processo de envelhecimento. É preciso que os ossos e a cartilagem apóiem o envelhecimento do corpo, embora as células que os produzem se tornem menos ativas com o tempo. Outros órgãos, tais como os rins, o coração e o fígado devem ser operados para ter um tempo de vida maior. A engenharia tecidual foi desenvolvida para substituir, reparar ou reconstruir tecidos ou órgãos perdidos ou danificados por acidentes ou doenças graves através da utilização e desenvolvimento de novos materiais, que sejam biocompatíveis, bioabsorvíveis, porosos, entre outras características. Os scaffolds são arcabouços tridimensionais porosos e são utilizados na regeneração de tecidos para seu estado natural e suas funções, que é fundamental para a engenharia tecidual. Eles podem ser classificados em arcabouços que induzem a migração e o crescimento celular e em arcabouços carreadores de células osteogênicas autógenas, que foram colonizadas em biorreatores e subsequentemente reimplantadas no paciente. Tais scaffolds podem ser naturais ou sintéticos. O objetivo deste trabalho é avaliar o compósito poroso de hidroxiapatita - titânia (HATiO2), em três composições diferentes (50% HA - 50% TiO2, 60% HA - 40% TiO2, 70% HA - 30% TiO2) para obter scaffolds utilizados para engenharia tecidual óssea. Os corpos de prova foram produzidos pelo método da esponja polimérica, utilizando bicarbonato de sódio como ligante e floculante. A sinterização foi realizada em três temperaturas: a 1250ºC; 1300ºC e 1350ºC. As propriedades analisadas foram: resistência à compressão e dureza através das normas da ASTM, porosidade aparente, densidade aparente, retração linear de queima e absorção de água, pelo método de Souza Santos para argilas. Os resultados obtidos mostraram-se bastante satisfatórios, onde foi mostrado que os corpos cerâmicos porosos obtiveram valores de resistência à compressão e dureza coerentes com os da literatura e superiores aos da hidroxiapatita pura. Realizou-se também uma caracterização estrutural das amostras via difração de raios - x (DRX), microscopia eletrônica de varredura (MEV) e espectroscopia por infravermelho com transformada de Fourier (FT-IR). Com base nos resultados mecânicos e de caracterização estrutural, foi escolhida a amostra com composição de 50% HA - 50% TiO2 sinterizada a 1350ºC para realização de ensaios in vitro, onde foram avaliadas citotoxicidade e crescimento celular de osteoblastos e fibroblastos de camundongos. Os resultados indicaram que o compósito é biocompatível e que as células cresceram nos scaffolds. De forma geral, pode-se concluir que todas as amostras são indicadas para a utilização como matéria prima para aplicação em engenharia tecidual óssea. A amostra com 50% HA - 50% TiO2 apresentou melhores características para a realização dos ensaios in vitro realizados neste trabalho e pode-se indicar esta para a realização de ensaios in vivo, onde devem ser avaliadas as características de citotoxicidade e crescimento de células ósseas em animais, por um período de 15 e 30 dias, conforme normas da área de saúde
Abstract: As we witness an improvement in the technology applied to human health, life expectancy increases, even though not every part of the body can maintain their functions with the aging process. It is necessary that bones and cartilage support the body's aging, even if the cells that produce them become less active with time. Other organs, such as kidneys, heart and liver must be operated to have a higher lifetime. Tissue engineering has been developed in order to replace, repair or rebuild tissues or organs lost or damaged due to accidents or serious diseases through the use and development of new materials that are biocompatible, bioabsorbable, with porosity among other characteristics. Scaffolds are a kind of porous tridimensional net and they are used on tissues regeneration to their natural state and functions, which is fundamental for tissue engineering. They can be classified as scaffolds that induce migration and cell growth and as carrier scaffolds for autogenous ostheogenic cells, which were colonized inside bioreactors and then redeployed on the patient. Those scaffolds can be natural or synthetic. This research aimed to evaluate hydroxyapatite-titanium oxide (HA-TiO2) with three different compositions (50% HA - 50% TiO2, 60% HA - 40% TiO2, 70% HA - 30% TiO2) to obtain scaffolds used for bone tissue engineering. Samples were made by the polymeric sponge method, using sodium bicarbonate as a binder and flocculating agent. Sintering was carried out at 1250ºC; 1300ºC e 1350ºC. It was analyzed compressive strength and Vickers hardness using ASTM Standards, apparent porosity, apparent density, burning linear retraction and water absorption by Souza Santos method used for clays. Results proved satisfactory showing that ceramic bodies obtained compressive strength and Vickers hardness according to literature and higher than those for pure hydroxyapatite. Samples structural characterization was done by x-ray diffraction (XRD), scanning electronic microscopy (SEM) and Fourier transformed infrared (FT-IR). It was chosen 50% HA - 50% TiO2 sintered at 1350ºC based on its mechanical properties and structural characterization and in vitro essays were done to evaluate citotoxicity and mouse osteoblasts and fibroblasts cell growth. Results have shown that the composite is biocompatible and the cell growth above scaffolds surface. In general, samples can be recommended for use as raw material for bone tissue engineering application. The sample with 50% HA - 50% TiO2 showed better characteristics for in vitro essays done and it can be recommended for in vivo essays where citotoxicity and bone cell growth in animals during 15 and 30 days, according to health standards
Doutorado
Materiais e Processos de Fabricação
Doutor em Engenharia Mecânica

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Backović, Marija [Verfasser]. "Thermodynamic optimization of the PbO-ZrO2-TiO2 (PZT) system and its application to the processing of composites of PZT ceramics and copper / vorgelegt von Marija Čančarević." Stuttgart : Max-Planck-Inst. für Metallforschung, 2007. http://d-nb.info/995377243/34.

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Pereira, Nathália Marcelino. "Preparação e caracterização de compósitos binários e ternários compostos de RuO2, TiO2 e FeOx para serem utilizados como catalisadores da reação de Fenton." Universidade Federal de Alagoas, 2014. http://www.repositorio.ufal.br/handle/riufal/1192.

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Synthetic dyes are one of the highest pollutants of water resources, when disposed improperly they can cause a lot of damage to the aquatic ecosystems and the human health. Alternative processes to the degradation of such effluents, as Advanced Oxidation Processes (AOPs), are gaining more prominence. They are non-selective, do not produce residues and have a high rate of oxidation. Among the AOPs, the Fenton reaction is the most promising. However, there is still a great limitation for industrial application due to the small range of pH when the reaction occurs, and the large amount of sludge [Fe(OH)x] generated at the end of the process. To overcome these limitations, an alternative is the use of solid catalysts containing iron. This study proposes the development of composites based on RuO2, TiO2 and FeOx for use as catalysts in the Fenton reaction. The yellow sun dye was used as the pollutant model. The catalysts were deposited on a support of titanium by thermal decomposition. The catalysts were synthesized with ternary compositions (containing 10, 20, 40 and 60% of iron) and with binary compositions (containing 70% of iron), where materials were developed containing only Fe and Ru and containing only Fe and Ti. The efficiency and stability of these catalysts were evaluated, as well as the way how these materials are affected when there are changes during the synthesis process. The parameters analyzed were O2 injection during the calcination, increasing the calcination temperature and catalyst mass. The catalysts have been characterized by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The compositions containing 40, 60 and 70% of Fe were efficient in the oxidation of the chromophore group of the dye, with degradation rate of 80.13%, 90.03% and 75.41% (with Ru) and 60.39% (with Ti), respectively. The compositions with low proportions of Fe (10 and 20%) did not have good results, the decolorization rate was 3.53% and 27.81% respectively. The MEV analysis showed similar results for all the compositions, with mud-cracked surface as predominant surface. The EDX analysis data indicates uneven surfaces on the composition for all the studied catalysts. Some catalysts compositions showed efficiency, but the low stability of these materials promotes its phasing out.
Os corantes sintéticos são um dos maiores poluentes de recursos hídricos, quando despejados de forma inadequada causam uma série de danos aos ecossistemas aquáticos e à saúde humana. Métodos alternativos para a degradação desse tipo de efluente, como os processos oxidativos avançados (POA’s), vêm ganhando cada vez mais destaque. Estes são processos limpos, não seletivos e possuem alto poder de oxidação. Dentre os POA’s, a reação de Fenton é o mais promissor. No entanto, há ainda uma grande limitação para sua aplicação industrial devido à pequena faixa de pH para a reação e à grande quantidade de lama [Fe(OH)x] gerada ao final do processo. Para superar essas limitações, uma alternativa é o uso de catalisadores sólidos contendo ferro. O presente trabalho propôs desenvolver compósitos a base de RuO2, TiO2 e FeOx para serem utilizados como catalisadores da reação de Fenton. O corante amarelo sol foi o poluente modelo. Os catalisadores foram depositados em um suporte de titânio expandido mediante decomposição térmica. Foram sintetizados catalisadores com composições ternárias, contendo 10, 20, 40 e 60 % de ferro, e catalisadores com composições binárias, com 70% de ferro, onde foram desenvolvidos materiais contendo apenas Fe e Ru e materiais contendo apenas Fe e Ti. A eficiência e a estabilidade desses catalisadores foram avaliadas, e o modo como esses materiais são afetados quando alguns parâmetros durante o processo de síntese são alterados também foi investigado. A injeção de O2 durante o procedimento de calcinação, o aumento da temperatura de calcinação e o aumento da massa do catalisador foram os parâmetro estudados. Os catalisadores foram caracterizados por microscopia eletrônica de varredura (MEV) e por energia dispersiva de raios X (EDX). As composições contendo 40, 60 e 70% de Fe foram eficientes na oxidação do grupamento cromóforo do corante, apresentando 80,13%, 90,03% e 75,41% (com Ru) e 60,39% (com Ti) de degradação, respectivamente. Já as composições catalíticas com baixas proporções de ferro, 10 e 20%, não tiveram bons resultados, sendo a remoção de cor de apenas 3,53% e 27,81% respectivamente. As análises por MEV apresentaram resultados bem similares para todas as composições, onde a superfície prioritária foi a de barro-rachado. Os dados obtidos por EDX indicam superfícies não uniformes quanto à composição para todos os catalisadores estudados. Para os parâmetros avaliados, nenhum contribuiu de forma significativa no aumento da eficiência e da estabilidade dos catalisadores. Algumas composições catalíticas se mostraram eficientes, mas apresentaram baixa estabilidade, promovendo a gradual desativação dos catalisadores.

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Hadj-Aissa, Aurélie. "Corrélations entre les propriétés physico-chimiques et l’efficacité photocatalytique d’un matériau cimentaire enrichi en TiO2." Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10056.

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La pollution atmosphérique urbaine pose des problèmes au niveau de l'environnement et de la santé publique pour plus de la moitié de la population mondiale. Afin de réduire la pollution de fond dans les villes, un matériau cimentaire innovant a été développé et permet de dégrader les polluants atmosphériques grâce à ses propriétés photocatalytiques induites par l'ajout de TiO2. Ce travail a porté sur la corrélation entre les propriétés physico-chimiques et l'efficacité photocatalytique d'un mortier enrichi en TiO2 lors de la dégradation de 2 composés organiques volatils (COV), le formaldéhyde et le toluène ainsi que sur un mélange d'oxydes d'azote (NOx). Le taux de présence de la surface en dioxyde de titane, le pourcentage relatif de titane et l'absorbance des photons UV par TiO2 ont été respectivement déterminés par spectroscopie Raman, microscopie électronique à balayage couplé à une analyse X et spectroscopie UV-visible par réflexion diffuse. La proportionnalité entre ces 3 grandeurs a été démontrée. L'efficacité photocatalytique des matériaux cimentaires enrichis en TiO2 a été mise en évidence pour la dégradation des 2 COV et des NOx. L'efficacité photocatalytique est reliée à la présence de TiO2 en surface ainsi qu'à la capacité de TiO2 à absorber des photons UV. La matrice cimentaire permet également, à l'obscurité, de réduire significativement la concentration en formaldéhyde. L'étude de l'influence des paramètres matériaux et environnementaux a montré l'importance de la teneur en TiO2, du flux lumineux et de l'humidité relative sur les propriétés photocatalytiques du mortier et permis de contribuer à une meilleure compréhension des réactions intervenant lors de la dégradation des polluants par un matériau cimentaire photocatalytique
More than half of the world population is exposed to urban air pollution which poses problems for the environment and human health. To reduce the background of the pollution in cities, an innovative cementitious material has been developed and used to degrade pollutants thanks to its photocatalytic properties induced by the addition of TiO2. This work was focused on the correlation between physicochemical properties and the photocatalytic efficiency of a mortar enriched with TiO2 during the degradation of two volatile organic compounds (VOCs), formaldehyde and toluene as well as a mixture of nitrogen oxides (NOx). The occurence rate of of titanium dioxide on the surface, the relative percentage of titanium and the absorptance of UV photons by TiO2, respectively, were determined by Raman spectroscopy, scanning electron microscopy coupled with X-ray analysis and UV-visible diffuse refectance spectroscopy. Proportionality between these three variables has been demonstrated. The photocatalytic efficiency of TiO2-rich cementitious materials has been demonstrated for the degradation of the 2 VOCs and also for NOx. The photocatalytic efficiency is related to the presence of TiO2 on the surface and the ability of TiO2 to absorb UV photons. The cement matrix can also, in the dark, reduced significantly the concentration of formaldehyde. The study of the influence of materials and environmental parameters showed the importance of the TiO2 content, the luminous flux and relative humidity on the photocatalytic properties of the mortar and allowed to contribute to a better understanding of the reactions occurring during the degradation of pollutants by a photocatalytic cementitious material

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Zhang, Rui. "Transition-metal-based composite and hybrid nanomaterials for catalytic applications." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19224.

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In der Entwicklung von Technologien für die nachhaltige Erzeugung, Speicherung und Umwandlung von Energie werden Hochleistungskatalysatoren benötigt. Im Rahmen dieser Arbeit werden verschiedene Übergangsmetall-basierte Katalysatoren, namentlich TiO2/Kohlenstoff-Komposite, anorganisch-organische Hybridsysteme auf Basis von NiFe Phosphonaten sowie Ni Phosphide, synthetisiert, charakterisiert und hinsichtlich ihrer photo- und elektrokatalytischen Eigenschaften untersucht. Es wird gezeigt, dass die Grenzflächeneigenschaften der TiO2/C-Komposite signifikant durch die Gestaltung des Heizvorgangs während der Synthese beeinflusst werden. Insbesondere der Einsatz von Mikrowellenstrahlung vermag die Synthese von Kohlenstoff-basierten Materialien positiv zu beeinflussen. Schnelles Erwärmen führt zu stärkeren Wechselwirkungen zwischen Nanopartikeln und Kohlenstoff, einheitlicheren Beschichtungen und kleineren Partikeln mit schmaleren Partikelgrößenverteilungen, wodurch die photokatalytische Aktivität verbessert wird. Schichtartige, hybride NiFe-Phenylphosphonat-Materialien werden ausgehend in Benzylalkohol dargestellt und ihre Aktivität in der OER im basischen Milieu untersucht. Die Hybridpartikel werden in-situ in NiFe-Hydroxid Nanoschichten umgewandelt. Röntgenspektroskopische Untersuchungen deuten auf eine induzierte, teilweise verzerrte Koordinationsumgebung der Metallzentren im Katalysator hin. Die Kombination der synergistischen Effekte zwischen Ni und Fe mit den strukturellen Eigenschaften des Hybridmaterials ermöglicht einen effizienten Katalysator. Weiterhin werden Nickel-Phosphide durch die thermische Behandlung der Phenyl- oder Methylphosphonate des Nickels, welche Schichtstrukturen aufweisen, in H2(5%)/Ar-Atmosphäre synthetisiert. Ni12P5, Ni12P5-Ni2P und Ni2P Nanopartikel, die mit einer dünnen Schicht aus Kohlenstoffmaterial beschichtet sind, werden erhalten. Ni12P5-Ni2P und Ni2P Nanopartikel katalysieren die Wasserstoffentwicklungsreaktion (HER) im Sauren effektiv.
High-performance catalysts play a key role in the development of technologies for sustainable production, storage, and conversion of energy. In this thesis, transition-metal-based catalysts, including TiO2/carbon composites, hybrid organic-inorganic NiFe phosphonates, and Ni phosphides are synthesized, characterized, and investigated in photocatalytic or electrocatalytic reactions. TiO2 is frequently combined with carbon materials, such as reduced graphene oxide (rGO), to produce composites with improved properties. TiO2 is more efficiently stabilized at the surface of rGO than amorphous carbon. Rapid heating of the reaction mixture results in a stronger coupling between the nanoparticles and carbon, more uniform coatings, and smaller particles with narrower size distributions. The more efficient attachment of the oxide leads to better photocatalytic performance. Layered hybrid NiFe-phenylphosphonate compounds are synthesized in benzyl alcohol, and their oxygen evolution reaction (OER) performance in alkaline medium is investigated. The hybrid particles transformed in situ into NiFe hydroxide nanosheets. X-ray absorption spectroscopy measurements suggest the metal sites in the active catalyst inherited partly the distorted coordination. The combination of the synergistic effect between Ni and Fe with the structural properties of the hybrid results in an efficient catalyst that generates a current density of 10 mA cm-2 at an overpotential of 240 mV. Moreover, nickel phosphides are synthesized through thermal treatment under H2(5%)/Ar of layered nickel phenyl- or methylphosphonates that act as single-source precursors. Ni12P5, Ni12P5-Ni2P and Ni2P nanoparticles coated with a thin shell of carbonaceous material are produced. Ni12P5-Ni2P and Ni2P NPs efficiently catalyze the hydrogen evolution reaction (HER) in acidic medium. Co2P and CoP NPs are also synthesized following this method.

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Bahloul, Walid. "Génération in situ de dioxyde de titane par réactions d’hydrolysecondensations dans une matrice polymère fondu." Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10124/document.

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L’objectif de ce travail est de générer in situ des particules de dioxyde de titane dans une matrice polypropylène fondu au cours du procédé d’extrusion. La synthèse est basée sur des réactions d’hydrolyse-condensations d’un alkoxyde de titane (le n-tétrabutoxyde de titane). Une approche en milieu modèle a tout d’abord été développée offrant l’avantage de pouvoir travailler en milieu liquide sans prendre en compte de la viscosité du PP ni des effets de cisaillement. En se basant sur les données cinétiques déterminées en milieu modèle, la génération de ces particules de dioxyde titane a été ensuite transposée et modélisée dans le milieu polymère de masse molaire plus élevée. Les analyses chimique, structurale et morphologique ont permis de mettre au point l’élaboration in situ de nanocomposites PP/TiO2 présentant unestructure fractale avec des propriétés viscoélastiques particulières. Enfin l’étude des propriétés bactérienne de ce nanocomposite a mis en avant son pouvoir bactéricide (6Log) pour un taux de charge de 9 % massique
Polypropylene/Titanium dioxide (PP/TiO2) nanocomposites were prepared from an original method based on the hydrolysis-condensation reactions of titanium alkoxide inorganic precursor premixed with PP under molten conditions. The synthesis is based on sol-gel method without solvent through extrusion process. A second treatment in hot water was applied in order to improve final conversion degree. First, hydrolysis-condensation reactions of titanium n-butoxide precursor were studied in model medium. Based on a kinetic equation carried out in the model medium, then the synthesis of titanium dioxide particles was transposed and modelled in polypropylene medium with high molar mass. Chemical, structural and morphological analyses highlight the in situ synthesis of bactericides PP/TiO2 nanocomposites andpresenting a particular morphological and rheological behaviour

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Weng, Guan-Yu, and 翁冠羽. "A study on TiO2:InN nanoparticle composites." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/d529x3.

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碩士
國立交通大學
應用化學系碩博士班
103
In this study the nanoparticles (NPs) of InN, TiO2 and their composites of varying sizes have been synthesized by hydrothermal and sol-gel methods and characterized with different analytical techniques including XRD, SEM, TEM and optical absorption spectroscopy. Two different composite NPs with smaller InN adsorbed on larger TiO2 NPs (InN:TiO2) and vice versa (TiO2:InN) have been fabricated and studied for their opto-electronic and photo-catalytic properties. The former was found to have a very broad UV-Vis absorption spectrum extending from 390 nm to much beyond 800 nm; however, no photo-catalytic activity was observed under the irradiation of a Xe-lamp and no photo- luminescence (PL) was detected upon excitation at 230 nm. On the other hand, the latter composite was found to have a similar but a smaller absorption between 390 nm and 500 nm, with an increasing absorptivity at longer wavelengths. In addition, the TiO2:InN composite was found to exhibit a broad PL peak between 325 and 410 nm together with two sharper ones at 425 nm and 480 nm upon excitation at 230 nm. The photo-catalytic activity of the TiO2:InN composite NPs was found to be similar to that of pure TiO2 NPs under Xe-lamp irradiation.

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Liang, Yung-Chen, and 梁詠蓁. "Applications and property of TiO2/Graphene Photocatalyst composites." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/63391183376234260612.

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碩士
國立勤益科技大學
化工與材料工程系
102
The photocatalyst materials are usually TiO2 due to its high photocatalytic performance. This article explores the TiO2 photocatalyst modified with four different graphene modified by hydrothermal/ calcining and hydrothermal method, and various mass ratio of the graphene. (Photocatalyst composites were label as TxYC, x: weight percent, Y: graphene species, C: Calcining). Photocatalyst composites were characterized by field-emission scanning electron microscope (FESEM), X-ray diffraction(XRD), Raman spectroscopy, UV-vis diffuse reflectance spectra(UV-vis DRS), Fourier Transform infrared spectroscopy (FTIR) and photoactivity tests. The absorption spectra of the samples are shown that the narrowing of the band gap of TiO2 occurred with graphene introduction. The band gap of TiO2 is 3.08 eV, whereas the band gap of the photocatalyst composite has been slightly reduced to 2.50 eV. XRD and Raman analysis were suggested that addition of graphene cannot change crystalline structure of TiO2(Degussa, P25). FTIR spectra show that the chemical bonding between the graphene and TiO2. In photocatalytic tests, the visible light photocatalytic activity of TxGOA and TxGH1 composite are enhanced greatly on decomposition of methylene blue (MB).The photocatalytic activities of T4GOA samples are superior to that of TiO2, the methylene blue decomposition efficiency reached 100% only 30 min under UV light.

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Wu, Chih-Hong, and 伍志弘. "Photoconductivity of Single SnO2 Nanowire/TiO2 Nanoparticles Composites." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/94563534705616243222.

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碩士
國立臺灣大學
物理研究所
99
Individual SnO2 nanowire-based device has been fabricated by the gold microwire mask method and enhancement of photon-sensing property through combining single SnO2 nanowire with TiO2 nanoparticles have been investigated. It is found that the sensitivity of photoresponse of SnO2 nanowire can be enhanced by up to 50%. The underlying mechanism can be attributed to the charge separation process taking place between TiO2 nanoparticles and SnO2 nanowire due to Type II band alignment. The charge separation of photoinduced electrons and holes greatly reduces their recombination probability and accordingly enhances the photoconductivity of TiO2-decorated SnO2 nanowire. The result implies that SnO2 nanostructure can serve as a highly sensitive photodetector.

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34

Jhang, Jia-Hao, and 張家豪. "Newly Designed TiO2 Porous Composites and its Photocatalytic Properties." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/5v6u85.

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碩士
國立臺北科技大學
材料科學與工程研究所
106
In this study, a facile method for fabricating porous ceramic composites was proposed. Two main techniques were conducted for the manufacture of the porous ceramic composites, including the synthesis of gradient copolymer and the dispersion of nanopowder. The effects of the solid content of ceramic powder and the concentration of surfactant on the pore morphology of the porous ceramic composites were studied. Furthermore, the porous TiO2 composites were used as photocatalyst, which greatly improved the photocatalytic efficiency when compared to the traditional TiO2 powders. Because of the advantages of high surface area and high porosity, the porous ceramic composites have high potentials in the applications of drug release, solar cell, solid oxide fuel cell, filtration, and antireflection coating.

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35

Chen, Yu-chun, and 陳昱淳. "SnOx/TiO2 composites as anode materials for lithium ion battery." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/15727275185596898465.

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碩士
國立臺南大學
綠色能源科技研究所碩士班
100
Lithium ion batteries are being considered as the leading candidates for electric vehicles and energy storage system, because of its high energy density and excellent cycle performance. The nano-titanium based materials (e.g. TiO2 and Li4Ti5O12) are thought to replace the traditional system of carbon anode materials for lithium ion batteries to solve the safety aspects. TiO2 is studied because it is an abundant, low cost, and environmentally benign material. The nanostructured TiO2 is also structurally stable during Li insertion/extraction and is intrinsically safe by avoiding Li electrochemical deposition. These properties make TiO2 particularly attractive for high-power lithium-ion batteries. However, the specific capacity of TiO2 (180mAh/g) was lower than that of graphite materials. In this research, I searched the patents first about titanium-based anodes materials for lithium ion batteries, and then I tried to find the original and innovative research topics by patent map analysis. According to the results of patent map analysis, the research field of TiO2/SnO2 composites anode materials with high specific capacity is poor protected by patents. However, the process of TiO2/SnO2 composites syntheses usually needs higher temperature and wastes time. So, I used the chemical reduction and pyrolysis technique, a cheap and easy method to synthesize TiO2/SnO2 composites. The research is divided into two parts. Part 1: The chemical reduction way was developed to deposit nano-Sn composites onto the nano-TiO2 powders (denote as Sn/TiO2). The sequential pyrolysis process at 450oC, 500 oC and 600 oC successfully synthesize (Sn-Ti)O2 solid solutions (denoted as Sn/TiO2-450、Sn/TiO2-500 and Sn/TiO2-600). The morphologies of Sn/TiO2-450、Sn/TiO2-500 and Sn/TiO2-600, which transfered to a nano-cylinder structure, was observed by Transmission electron microscopy (TEM) analyses. The solid solution structures of Sn/TiO2-450、Sn/TiO2-500 and Sn/TiO2-600 were confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Among the Sn/TiO2 composites, Sn/TiO2-500 showed remarkably high capacity, high rate performance, and cyclability for lithium ion battery. Moreover, the differential scanning calorimetry (DSC) testing revealed that the safety of Sn/TiO2-500 is significantly higher than commercial anode materials, like graphite. Part 2: Although the Sn/TiO2-500 showed remarkably high capacity, high rate performance and cyclability for lithium ion battery, the performance of reversible capacity was still poor at the first cycle (about 45.9%). For this reason, I tried two different methods to solve this problem : 1. Adding the lithium elements into Sn/TiO2-500 composites. 2. Using SBR/CMC and PAA binder systems to replace the traditional PVDF binder system. According to the results, the second method, which uses SBR/CMC and PAA binders, obviously improved the columbic efficiency of Sn/TiO2-500 at the first cycle. Furthermore, the combination of SBR/CMC binder system and Sn/TiO2-500 showed a impressively improvement in cyclic capability and high specific capacity.

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36

Lui, Gregory. "Graphene-Wrapped Hierarchical TiO2 Nanoflower Composites with Enhanced Photocatalytic Performance." Thesis, 2014. http://hdl.handle.net/10012/8337.

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Increasing energy demands as well as the depletion of traditional energy sources has led to the need for the development and improvement of energy conversion and storage technologies. Concerns regarding climate change and environmental awareness has also created increased support for renewable energy and clean technology research. One technology of interest is the photocatalyst, which is a material that is able to use natural light irradiation to create electrical currents or drive useful chemical reactions. For this purpose, a strong photocatalytic material has the following properties: i) strong absorbance over a wide solar radiation spectrum; ii) high surface area for adsorbance of target species; iii) high electron efficiency characteristics such as high conductivity, long charge-carrier lifetimes, and direct pathways for electron transport; and iv) good chemical stability. All of these requirements serve to maximize the efficiency and overall output of the device, and are a means of overcoming the performance hurdle required for the commercialization of various energy conversion technologies. Unfortunately, current photocatalytic materials suffer from small absorbance windows and high recombination rates which greatly reduce the conversion efficiency of the catalyst. Titanium dioxide (TiO2), the most well-known and widely used photocatalyst, can only absorb light within the ultraviolet (UV) range – which accounts for only a small fraction of the entire solar spectrum. For this reason, the majority of recent research has been directed toward producing photocatalysts that are able to absorb light within the visible and infrared range in order to maximize the amount of light absorbed in the solar spectrum. Other research is also being conducted to increase electrical conductivity and charge-carrier separation to further increase conversion efficiency. It is hoped that these two major problems surrounding photocatalysis can be solved by using novel functional nanomaterials. Nanomaterials can be synthesized using three main techniques: crystal structuring, doping, and heterostructuring. By controlling the structure of the crystal, materials of different phase, morphology, and exposed crystal facets can be synthesized. These are important for controlling the electronic properties and surface reactivity of the photocatalyst. Doping is the act of introducing impurities into a material in order to modify its band structure and create a red shift in light absorption. Lastly, heterostructuring is a method used to combine different photocatalysts or introduce co-catalysts in order to widen the range of absorption, encourage charge separation, or both. Many novel photocatalytic materials have been synthesized using these techniques. However, the next-generation photocatalytic material has remained elusive due to the high cost of production and complexity of synthesis. This thesis proposes a novel photocatalytic material that can be used in photocatalyzed waste-water remediation. Graphene-wrapped hierarchical TiO2 nanoflowers (G-TiO2) are synthesized using a facile synthesis method. TiO2 is a material of particular interest due to its chemical and photo-corrosion stability, high redox potential, strong electronic properties, and relative non-toxicity. Hierarchical structures are highly desired because they are able to achieve both high surface area and high conductivities. Graphene hybridization is a popular method for creating composites with highly conductive networks and highly adsorptive surfaces. To the best of my knowledge, the hybridization of graphene on hierarchical TiO2 structures without pre-functionalization of TiO2 has not yet been demonstrated in literature. Therefore, it is proposed that the use of such a material would greatly simplify the synthesis process and enhance the overall photocatalytic performance of TiO2 over that of commercial TiO2 photocatalysts. In the first study, hierarchical TiO2 nanoflowers are synthesized using a solvothermal reaction. It is then shown that under UV irradiation, the hierarchical TiO2 material is able to outperform commercial TiO2 material in the photodegradation of methylene blue (MB). Further characterization shows that this improvement is explained by a higher electrical conductivity, and exists in spite of having a lower specific surface area compared to the commercial material. In the second study, G-TiO2 is synthesized by mixing hierarchical TiO2 nanoflowers with graphene oxide (GO) and reducing GO in a hydrothermal reaction. Photocatalytic tests show that this hybridization further improves the performance of the hierarchical TiO2. Further studies reveal that an optimal graphene loading of 5 wt% is desired in order to achieve the higher rate of MB decomposition, and greatly outperforms P25 in this task. Characterization shows that G-TiO2 composites have increased specific surface area and electrical conductivity compared to the hierarchical TiO2 nanoflower. It is believed that this work will provide a simple and efficient avenue for synthesizing graphene–TiO2 composites with greatly improved photocatalytic activity. This work may also find use in other photocatalytic applications such as chemical deconstruction and manufacturing, hydrogen production, solar cells, and solar enhanced fuel cells.

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Chen, Jhih-Hao, and 陳志豪. "Preparation and characterization of Polyaniline/TiO2 coated iron oxide composites." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/60534873854383946595.

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碩士
國立雲林科技大學
環境與安全衛生工程系
103
In this study, iron oxide nanoparticles (Fe3O4) of core material. Make use of Sol-gel method, titanium dioxide (TiO2) coated iron oxide on the surface. And then use of sodium dodecylbenzenesulfonate as surfactant. In situ polymerization reaction of acidic solution, discuss with different content of aniline hydrochloride. Preparation of polyaniline/titanium dioxide coated iron oxide composites by using XRD, UV-Visible, FTIR, TGA, magnetic properties, particle size, and conductivity analysis. XRD results showed that Fe3O4@PANI composites presented as inverse spinel type structure, PANI/Fe3O4@TiO2 composites presented as anatase structure. UV-Visible results showed that the composites have two characteristic peaks of polyaniline. At about 430nm is caused by hydrochloric acid doped resulting from protonated amino groups. After 700nm, the characteristic absorption peak is caused by the polyaniline quinone ring π-π* electronic transition. FTIR results showed that the composites can confirm the functional group structure of polyaniline. TGA results showed that Fe3O4@PANI and PANI/Fe3O4@TiO2 composites compared with pure polyaniline, thermal stability increased significantly. Magnetic properties analysis showed that Fe3O4@PANI and PANI/Fe3O4@TiO2 composites with the addition of aniline hydrochloride increases, saturation magnetization and residual magnetization are showing downward trend. Conductivity and particle size analysis showed that Fe3O4@PANI composites, when 3g of aniline hydrochloride dosage, the conductivity of up to 6.64×10-1S/cm (average particle size=750.1nm). PANI/Fe3O4@TiO2 composites, when 5g of aniline hydrochloride dosage, the conductivity of up to 9.49×10-1S/cm (average particle size= 805.5nm).

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38

Lo, Kun-Yuan, and 羅琨元. "Photocatalytic Characterization of Visible Light Activatable TiO2/Carbon Nanotubes Composites." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/81423173549884416790.

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碩士
國立清華大學
材料科學工程學系
98
Carbon nanotubes are uniformly coated with titanium dioxide by sol-gel technique. Morphology, composition, and photoreactivity of the as-made composite are investigated by electron microscopy, X-ray diffraction, UV-Visible spectrum, and Photoluminescence spectroscope data, respectively. The composites show a superior efficiency of photocatalysis than Degussa Aeroxide® P25 in photo-degradation experiment. Due to the excellent conductivity of carbon nanotubes, the photoelectron excited in titanium dioxide can be easily transferred to carbon nanotubes. As a result, the recombination kinetic of exciton is prolonged, and the photocatalysis of titanium dioxide is improved. Moreover, the high specific surface area of carbon nanotubes provides substantial amount of adsorption sites and therefore improve performance of photo-degradation experiment.

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39

Weng, Wei-Peng, and 翁偉芃. "Preparation and properties of electrospun MWCNT/TiO2/PAN nanofiber composites." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/55122928417854193708.

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碩士
國立清華大學
材料科學工程學系
98
Liquid-phase suspension photocatalysis of TiO2 nanoparticles usually accompanies drawbacks such as particle agglomeration, UV hindrance and difficult recovery process. Immobilizing the nanoparticles on polymeric fibers provides an effective solution to these problems. In this study, electrospun PAN-based nanofiber composites containing MWCNTs and P25-TiO2 are prepared, in order to eliminate the drawbacks regarding liquid-phase suspension photocatalysis, and to enhance the long-term stability of the composites. Under appropriate experimental parameters, composite fibers with diameter of few hundred nanometers are successfully produced. TiO2 particles are uniformly embbed in the nanofibers, and the composites still exhibit superior photocatalytic performances. The Methylene Blue (MB) photodegradation efficiencies are comparable between samples containing MWCNTs and those without MWCNTs. Besides, the nanocomposites possess reusability; MB degradation efficiency is maintained at approximately 90% during 5 runs of use for both samples. Furthermore, upon 20 hours UV irradiation, the composite containing MWCNTs shows less damaged fiber morphology than that without MWCNTs. According to MB degradation experiment, over 90% MB are degraded upon 4 hours UV irradiation; hence, the addition of MWCNTs provides sufficient stability to the composites.

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40

Su, Chien, and 蘇岍. "Applications of Chitosan/TiO2 composites: copper ions adsorption and antimicrobes." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/w3tqf2.

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碩士
國立陽明大學
環境與職業衛生研究所
107
Recently, much attention has been given to heavy metal soil pollution, much of which comes from wastewater. Over time, most pollution of agricultural land in Taiwan has come from industrial waste which came as a result of industrial development. Therefore, wastewater containing heavy metal contaminants has become a prominent environmental issue. These days, people tend to spend most of their time indoors. As a result, microbial contamination has become a more pressing issue. Due to copper’s lower cost than silver and its recyclability from wastewater, copper has become the most studied antibacterial material. In this study, we will focus on the adsorption of copper in wastewater by chitosan absorbent, and the antibacterial activity of chitosan composites after absorbing copper. We will also be comparing the different absorbent efficiency and antibacterial activity between the chitosan (CS) and chitosan-TiO2 (CST) composites. The CS and CST composites are characterized by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), nitrogen adsorption/desorption isotherm at 77K, Fourier Transform Infrared Spectrometer (FT-IR), Thermogravimetric Analysis (TGA). The adsorption ability was tested by the spectrophotometry-Bis(cyclohexanone)oxaldihydrazone (BCO) method in the lab along with a series of copper nitrate solution of varying concentrations. Antimicrobial activity was evaluated by the zone of inhibition (ZOI) assay against E. coli (Gram-negative) and S. epidermidis (Gram-positive). The results show the best Qt was the condition CS with 3% glutaraldehyde and exchange with ammonia solution with 300 ppm initial concentration, which of the Qt is 30.73 mg/g. All of the samples had antimicrobial properties. Respectively, the antimicrobial efficacy was affected by the copper ion more than the TiO2 and glutaraldehyde. The Qt results of adsorbing the 17636 mg/L Cu2+ from industry were about 330 mg/g, the Qt after dilution 50 times were about 10 mg/g, and the ZOI area of these two concentration were 50 times difference. The cost-benefit analysis showed that the cost of our materials were about 70 times more expensive than the treatment the industry is using now. However, there may be lower costs possible in treating polluted sludge. The produced material cost every year was about 1.7 billion NTD. With the results from our experiments, we found that the composites showed a good removal efficiency on copper ions. This indicates that the CS/CST composites after absorption demonstrated excellent antimicrobial activity, and could solve the copper ion pollution problem in wastewater as well as improving the air quality as a result of killing microbes.

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41

Wu, Min-Tsung, and 吳旻聰. "Synthesis of TiO2 and TiO2-SiO2, Carbon-TiO2 Composites by Evaporation Induced Self- assembly and Their Applications in Dye-sensitized Solar Cell." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/36308210912823977674.

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博士
國立臺灣大學
化學研究所
102
The size tunable TiO2 sphere, SiO2-TiO2 composite and C-TiO2 composite were synthesized via a simple evaporation induced self-assembly (EISA) process. First, We report a simple method for the preparation of the size tunable TiO2 sphere from titanium (IV) isopropoxide and nonionic surfactant colloids (triton X-100) as the template. The synthetic procedure is easy to control by changing the Ti/H2O ratios in the process of evaporation-induced self-assembly. We are able to tune the size of sphere TiO2 particles with diameters of 500 nm, 700 nm, and 1100 nm, named as TiO2-500, TiO2-700 and TiO2-1100. They are suitable for the fabrication of DSSCs with a comparable efficiency to the commercial photocatalyst P25. The three different TiO2 sphere size were applied as a scattering overlayer on a transparent nanocrystalline TiO2 film, bi-layered dye-sensitized solar cells (DSSCs) have been fabricated. In second part, SiO2-TiO2 composite has been reported, which uses nonionic surfactant colloids (triton X-100) as the template as a template, a titanium (IV) isopropoxide and Tetraethoxysilane as a titanium and silica source by evaporation-induced self-assembly. The SiO2-TiO2 composite can be easily shaped. The synthesized SiO2-TiO2 composite were then applied as the as a scattering overlayer on a transparent nanocrystalline TiO2 film, bi-layered dye-sensitized solar cells (DSSCs) have been fabricated. As a result the photovoltaic conversion efficiency (η) of DSSC was improved with our materials. In addition, we synthetize C-TiO2 composite by the same method. It has been investigated as a counter electrode for dye-sensitized solar cells.

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42

Shen, Yi-Min, and 沈翌民. "Photocatalytic degradation of TMAH from aqueous solution with GO/TiO2 composites." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/05727729724595576773.

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碩士
國立中興大學
環境工程學系所
103
In recent years, with high-technology industries developed rapidly and extensively, more and more nitrogenous contaminations were found in aqueous environment, i.e. tetramethylammonium hydroxide (TMAH) or ammonium (NH4+). This type of pollution would lead to eutrophication or aquatic organism death. The removal performance of nitrogenous contaminations by traditional wastewater treatment is too low to reach effluent standards. This study prepares the graphene oxide/titanium dioxide (GO/TiO2) nanocomposites which can photodegrade TMAH in aqueous solutions. The TMAH conversion by GO/TiO2 showed the best performance at solid/liquid ratio of 1.0 g/L, 5% GO contents, 400oC calcinations temperature, and reached 73.9%. This is higher than TiO2(60.6%)and Degussa P25(67.6%). The removal efficiency for TMAH appeared less than 19.6% in the background experiment, which includes photolysis and dark reaction. This means that major mechanism in the photoreaction process was attributed to photocatalytic degradation. The TMAH conversion increased with solution pH, temperature and light intensity but decreased with solution ionic streagth and initial TMAH concentration. These results suggest that photodegradation process of TMAH with GO/TiO2 nanocomposite is possibly a promising technology in wastewater treatment of high-tech industry.

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43

Wu, Ching-Fang, and 巫菁芳. "Study of Titanium Dioxide/Silver (TiO2 /Ag) Composites Photocatalyst for Acetone Removal." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/64014571519080994867.

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碩士
國立交通大學
環境工程系所
95
Titanium dioxide has been extensively used as photocatalyst in nowadays. But aggregation between nanoparticles results in a lower photoactivity. Generally, surfactants are added to make nanoparticles disperse well. However, surfactants belong to organic matters, it could be decomposed by illumination of sunlight or UV lamp. This study focuses on the relationship between pH status and surface charges of particles, and attempt to synthesize well-bonding composites by means of different surface charges between TiO2 and Ag carrier. The experiments showed that TiO2 can’t adsorb on the surface of Ag carrier in both acidic and alkaline solution due to the same surface charges. A highly-dispersed TiO2/Ag composites are obtained in a neutral solution (pH5.8) where zeta potential of TiO2 and Ag carrier is +27, -10mV, respectively. Strong electric attraction between TiO2 and Ag carrier in neutral solution spontaneously results in a highly-dispersed TiO2/Ag composite, and it is found excellent for the removal of acetone due to chemical binding Ti-O-Ag.

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44

Kuan-HuaLi and 李冠嬅. "Study on photocatalytic properties of Fe2TiO5 thin film and TiO2/Fe2O3 composites." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/06843329773201454698.

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碩士
國立成功大學
地球科學系碩博士班
101
TiO2/Fe2O3 and Fe2O3/TiO2 thin films are fabricated by using r.f. magnetron sputtering system. They can be applied within the Vis-light range and enhanced their photocatalytic efficiency. We will investigate photocatalytic properties and mechanism between the TiO2/Fe2O3 (Fe2O3/TiO2) film and Fe2TiO5 film. TiO2 films possess a polycrystalline anatase phase by XRD examination. The film thickness and grain size of TiO2 films increase with the increasing sputtering time, which have a pure composition of Ti and O elements. The surface roughness of TiO2 films becomes larger with the increasing film thickness. The band gap and photocatalytic efficiency are related to the ratio of Ti3+/Ti4+ in the TiO2 films. From the XRD result, Fe2O3 films are the pure hemanite phase. The film thickness of Fe2O3 films increases with time observed by FE-SEM, and they only have the elements of Fe and O atoms by EDS analyses. The roughness and band gap of these films are irregular due to the posting annealing. The photocatalytic activity of Fe2O3 films increases with the increasing film thickness. The composite films of TiO2(90 min)/Fe2O3(20 min) and Fe2O3(20 min)/TiO2(90 min) are individually pure anatase and hematite phase. The band gap of TiO2(90 min)/Fe2O3(20 min) is within the UV-light wavelength, while that of Fe2O3(20 min)/TiO2(90 min) is in the Vis-light range. The two composite films have a similar photocatalytic ability, which is better than that of single TiO2 and Fe2O3 films. This may be resulted from electrons or holes can be hopped between valence band and conduction band to reduce the recovery of electrons and holes. Consequently, the photocatalytic ability is enhanced. Fe2TiO5 film is polycrystalline orthorhombic phase from XRD investigation. The band gap of Fe2TiO5 films is in the Vis-light region. The photocatalytic efficiency is very good and similar with that of the composite film. The photocatalytic mechanism is related to the ratio of Fe2//Fe3+ and Ti3+/Ti4+ in the Fe2TiO5 film. It is because the charge transfer between the element with different chemical states, and thus it can effectively separate the electron and hole pairs to promote the photocatalytic activity.

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45

Chen, Hung-Ming, and 陳宏銘. "Synthesis and Characterization of TiO2/4-methoxycinnamic acid Composites for Ultraviolet Shielding." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/9439x5.

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碩士
國立中山大學
材料科學研究所
95
The goal of this experiment is to explore the absorption and reflection of UV light by TiO2/MCA in physical mixing and chemical synthesis. The experiment shows that TiO2/MCA in anatase structure is better than in amorphous structure (with FT-IR. UV-VIS. XRD and Raman spectrum). The first experiment shows that the small TiO2 particle size (290 nm) has better UV absorption than large TiO2 particle (400 nm) in the same mole. After TiO2/MCA(P) exposed to the UV source, the concentration of MCA in TiO2 anatase structure will decrease much than in TiO2 amorphous structure. In the second experiment, the raman peak in 1070 cm-1 proofs that the existence of the Ti-O-C structure. In addition, the FT-IR spectrums peck shows a part of TiO2/MCA has no chemical bonding, and also produces sparse ester (1100 cm-1 . 1300 cm-1). If the peak (1100 cm-1 . 1300 cm-1) were not exist, compare with the previous step, the level of chemical bonding will increase, and it will produce even less ester. In conclusion, The direction of UV absorption of TiO2/MCA(C1. C2. C3) and TiO2/MCA(P) are extremely similar.

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46

Yi-Jun, Lin. "Nanostructured TiO2/Conjugated Polymer and Fe3O4/PAA Composites: Synthesis, Properties and Photovoltaic Application." 2007. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2001200700260700.

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47

Lin, Yi-Jun, and 林怡君. "Nanostructured TiO2/Conjugated Polymer and Fe3O4/PAA Composites: Synthesis, Properties and Photovoltaic Application." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/49156436291311697783.

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博士
國立臺灣大學
化學工程學研究所
95
This thesis divided into three parts. The synthesis of metal oxide materials, including titanium dioxide (TiO2) and iron oxides (Fe3O4) were described in Chapter 1. The experimental procedures and characterization results of successful synthesis of crystalline TiO2, and Fe3O4 with various shapes and morphologies were reported and discussed in this chapter. In the following part of this work, the synthesis and characterization of TiO2 nanocrystals with a rather small particle size distribution were presented. The effects of titanium precursor concentration, solvent, and water content on the morphology and particle size distribution of TiO2 colloids were also briefly discussed. The diameter of these titania spheres can be easily tuned from 50 to 252 nm by varying the precursor concentration from 0.68 mM to 1.94E-2 M. Titania thin film produced by evaporation-induced self-assembly (EISA) route were also studied, which has a highly ordered mesostructure, narrow pore-size distribution, relatively high specific surface area, and very good thermal stability. Moreover, the structure was stable up to 400℃ and contains channel walls with anatase nanocrystallites. Importantly, under modified film aging conditions, optically transparent and crack-free thin films were obtained by the deposition onto a compact TiO2 layer. A part of this chapter presented the methods used to synthesize and characterize the magnetite materials. In the chapter, a series of magnetic materials with different shapes and morphologies were proposed and studied. In organic/inorganic hybrid photovoltaic cells, the inherent incompatibility of inorganic particle and conjugated polymer frequently causes microscopic separation in the interface of two materials, thus significantly reducing its interfacial photo-induced charge transfer efficiency. In Chapter 2, a series of photoactive hybrids were prepared by the electrochemical polymerization of bithiophene into a nanoporous TiO2-coated ITO glass using chronopotential method in pure acetonitrile solution, or in a water/acetonitrile mixed solvent at different current densities. The growth conditions for the preparation of well defined smooth and adhesive polybithiophene films were demonstrated. Furthermore, the morphologies and electrochemical properties of the as-prepared polybithiophene/TiO2 photoactive hybrid materials were described in this chapter. In Chapter 3, it describes the details of the preparation of organic solar cells by in-situ electropolymerization method. In photovoltaic cells, the use of an additional blocking TiO2 layer was essential to avoid short circuiting and loss of current through recombination at the FTO electrode. A method of preparation of a compact TiO2 layer by spray pyrolysis technique, and its standardization for the solar cell fabrication was discussed. The nature, structure and morphology of this layer with increasing thickness was examined with scanning electron microscopy (SEM), and the effects of this compact layer on the photovoltaic properties of the corresponding solar cells were also studied by looking into the current(I)-voltage(V) characteristics of a solar cell. Influences of the spraying cycles of this compact layer were also investigated in this chapter. The results indicated that an optimum spraying cycles of compact TiO2 layer was found to be the key issue to give the best results in terms of photovoltaic properties, and the layers of blocking TiO2 film should lie in the optimized region. In our experimental, this corresponds to below 10 spraying cycles in terms of surface morphology and photovoltaic properties. The results of this thesis demonstrate that this study provides a facile and successful route for growing conducting polymer from the porous TiO2 film. The cell power conversion efficiency could be further improved by optimizing the in-situ polymerization conditions, polymer structures, film morphologies, and contacts of metal/polymer/inorganic interfaces.

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48

Lin, Kuan-Ting, and 林冠廷. "Microstructural Evolution and Interfacial Reactions between Ti Melt and ZrO2/ CaO/ TiO2 Composites." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/57w85u.

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49

Tsai, Chun-Wei, and 蔡君偉. "The Preparation of rGO/TiO2 Composites for Supercapacitor Electrode by Experimental Design Method." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/97929808600050725704.

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Abstract:

碩士
國立高雄應用科技大學
化學工程與材料工程系碩士在職專班
105
In this study, graphene oxide (GO) was prepared by the improved Hummer's method, and reduced graphene oxide (rGO)-TiO2 (rGO-TiO2) composites for manufacturing a supercapacitor, were obtained by reducing graphene oxide (GO) using TiO2 as photocatalyst. The optimal ID/IG ratio was obtained by using Box-Behnken Design, at weight ratios of TiO2/GO, reaction temperatures, photocatalytic times and stirring rates as experimental parameters during the photocatalytic reaction of GO converted to rGO. The optimized conditions were weight ratio of TiO2/GO at 2.48, photocatalytic time at 13 h, reaction temperature at 60 ℃, and stirring rate at 700 rpm. However, the ID/IG was predicted at 1.05, and the experimental results showed that ID/IG is 1.09, which is close to that predicted by the regression model. The electrochemical CV analysis shows that GO have a poor capacitive property (about 68.62 F/g). The photocatalytic reduction of graphene by UV-light has a specific capacitance of about 80.0 F/g. Nevertheless, as the increase of weight ratio of rGO/TiO2, the total capacitance was up to 112.06 F/g. By charge/discharge examination, GO, rGO and rGO/TiO2 show that the characteristic curves are triangularity, and exhibiting that the graphene material demonstrates a superb charge/discharge stability and reversibility. In fact, it could be used as an excellent ultra-capacitor electrode material.

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50

Lee, Fang-Ching, and 李方晴. "Photocatalytic Oxidation of Aqueous Ammonia over M-TiO2/SBA-15 Composites under Sunlight." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/66350633099647739104.

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Abstract:

碩士
國立中興大學
環境工程學系所
105
In this study, a systematic investigation on the performance and the product selectivity of the photocatalytic oxidation of aqueous ammonia under simulated sunlight by various synthesized catalysts with different treatment factors (e.g., ammonia concentration, pH, catalyst loading, and structural characteristics) was conducted. Titanium dioxide (TiO2) was synthesized by sol-gel method, and mesoporous SBA-15 by hydrothermal method using agricultural waste - rice husk ash (RHA). In order to enhance the ammonia oxidation rate and nitrogen yields, catalysts composed of Ag, Cu on TiO2 and SBA-15, as well as a self-assembled core-shell catalyst (A@C-T/S) was examined. The results showed (1) direct photodegradation of ammonia did not occurr under visible light irradiation, and pH 10 is the best condition for ammonia nitrogen degradation. (2) TiO2 size was measured at 10 ~ 20 nm. Therefore, TiO2 is covered on the SBA-15 surface, due to its larger size than SBA-15 pore size. (3) SBA-15 promotes the photocatalytic activity. Also, a pH drop that decreased ammonia nitrogen oxidation rate was observed throughout the process, constant pH 10 condition was thus applied to enhance photodegradation of ammonia. Ammonia nitrogen removal rate of 0.5% A-T and A@C-T/S were 80.9 % and 77.9 %, respectively. (4) Catalysts with SBA-15 and constant pH 10 condition effectively promoted ammonia nitrogen conversion to relatively less toxic nitrates or nontoxic nitrogen. Core shell catalyst, Ag@Cu-TiO2/SBA-15, showed great photocatalytic activity, and the highest selectivity for nitrogen in ammonia nitrogen photodegradation process.

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