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1
Vukicevic, Uros. "TiO2 nanorod polymer composite materials." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/7669.
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The remarkable characteristics of Ti02 are widely used, from everyday life applications (pigments, food/cosmetics additives) to more specialised systems, including photovoltaics and structural composites. Use in polymers is substantial (25% of all Ti02 produced), but most applications and research focus on commercial powders. A new generation of Ti02 nanoparticles has emerged, based on very small, single-crystals, with well-defined morphology and phase. A limited number of papers report the use of this new nanoscale Ti02 in polymer nanocomposites, and indicate improved properties. Although the synthesis of anisotropic nanoparticles (e. g. nanorods) has been well-reported, use in polymer nanocomposites remains largely unreported. This thesis broadly covers three topics: (1) synthesis of Ti02 nanorods using different sol-gel routes in presence of structure directing agents, (2) modification of the nanorod surface chemistry in order to control dispersion and surface properties and (3) fabrication of titania nanorod-polymer composites. Singlecrystal anatase nanorods were produced with variable aspect ratio (3-12), depending on the specific structure directing agent (SDA) used during synthesis. Due to organic functionalisation at the nanorod surface, nanorods could be well dispersed in chloroform. A new procedure, based on the self-cleaning ability of Ti02 under UV, was developed for removal of organics from the nanorod surface, without compromising the nanorod morphology, crystallinity or dispersibility. This powerful tool can be used to change the surface character of the nanorods to generate aqueous TNR dispersions. Stable dispersions were achieved using quaternary ammonium hydroxides to modify the surface electrostatically and sterically. Once dispersed individually, the surface can be further modified by sol-gel chemistry. Composite work involved blending both organic and water-soluble polymers with nanorod dispersions in chloroform and water, respectively, to produce composite films of exceptional optical transparency, even for nanorod loadings up to 30 wt%. The films possess very strong, wavelength-tuneable UV absorbance, which could be used in UV filters and optical limiting. The presence of SDAs or dispersants at the nanorodpolymer interface hinders strong adhesion, as evidenced by marginally lower tensile strength and thermal stability of the nanocomposites. The photo-stability of the nanorod composites is comparable to that of the pure polymer and better than that of composites with commercial equiaxed TiO2 nanoparticles.
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Steele, Karl Christopher. "Evaluation of TiO2 and Ag-TiO2, CuO-TiO2 composite films for self-disinfection activity." Thesis, University of Salford, 2009. http://usir.salford.ac.uk/26923/.
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The removal or killing of microorganisms on surfaces is of concern in the health care setting, food preparation areas and general work environment. The use of TiO2 photosterilisation has been proposed as an alternative to chemical disinfection of surfaces as a means to reduce the need for increasingly concentrated and aggressive chemicals necessary to kill disinfectant-resistant organisms. The objective of this research was to evaluate the ability of photocatalytic oxidation to reduce bacterial and viral contaminants on surfaces coated with TiOa and Ag-TiC^, TiO2-Ag, Cu-TiC^, TiO2-Cu. There are no British Standards that cover evaluation of such surfaces. A method for evaluation of photocatalytic surfaces was therefore developed from BS EN 13697:2001 and used to evaluate the activities of a variety of catalytic surfaces coated with TiO2, Ag and Cu and multi-layers of Ag-TiO2,TiO2-Ag, Cu-TiO2,TiO2-Cu. The antimicrobial activities were found to be dependent on the nature of the coating. Highest killing activities were obtained with Ag and Cu alone but combinations of Ag or Cu with TiO2were more active than TiO2 alone and also retained some self- cleaning activity. The results showed that the developed method was adaptable for determination of the antimicrobial activity of coatings with a wide range of activities producing 100% killing of Escherichia coll in times from 3 min up to 4 h. The results showed that it was possible to produce self cleaning self disinfecting surfaces and that surfaces with TiO2 on top, although having reduced activity compared to Ag or Cu, were durable and may have applications in the prevention of transmission of infections on surfaces in a wide range of applications.
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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’hexaneThis 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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Fan, Ka Ho. "Synthesis and evaluation of macroporous TiO2 composite photocatalyst /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?CENG%202006%20FAN.
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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 développéeThe 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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Dan, Chengyi. "Effects of nanoparticles on the microstructure and crystallographic texture evolution of two Aluminium-based alloys." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS147.
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Les effets des nanoparticules (cisaillables et non-cisaillables) sur l’évolution microstructurale et l'évolution de la texture cristallographique des deux alliages à base d’aluminium après laminage à froid ont été étudiés dans cette thèse. Un alliage Al-Sc contenant des nanoparticules cisaillables de Al3Sc et un composite Al-TiB2 contenant des nanoparticules non-cisaillables TiB2 sont étudiés. La microscopie électronique en transmission (MET), la diffraction d'électrons rétrodiffusés (EBSD) et l’analyse de la texture par la diffraction de neutrons sont utilisées pour caractériser le développement de la microstructure et la texture cristallographique lors du laminage à froid des 2 alliages.La restauration dynamique pendant laminage a été inhibée dans la matrice contenant des Al3Sc nanoparticules cisaillables et TiB2 non-cisaillables. Par conséquent, peu de cellules de dislocation ont été générées dans la matrice, ce qui limite la diminution de la taille des grains.Le développement de la texture de laminage est retardé par les nanoparticules cisaillables ou les particules non-cisaillables. Des bandes d’orientation de cube résiduelles se trouvent dans les matériaux contenant des particules cisaillables dans une matrice très déformée en raison de la limitation du glissement croisé. La réduction de la proption volumique des composantes de texture du laminage se produit dans les matériaux contenant de grandes particules non-cisaillables (de l’ordre d’un micromètre) en raison de la recristallisation dans les PDZs (Particle Deformation Zones), ce qui contribue également à la diminution des grains.De plus, le cisaillement de nanoparticules favorise le glissades en plan, ce qui conduit à une forte localisation des déformations et à l'apparition de bandes de cisaillement. La génération de bandes de cisaillement dépend de l'orientation et est dû au changement soudain des chemins de déformation et et de l'inhibition de la récupération dynamique. Les nanoparticules non cisaillables ont probablement pivoté avec la matrice environnante, ce qui pourrait constituer un nouveau mécanisme de déformationThe effects of shearable and non-shearable nanoparticles on the microstructure and crystallographic texture evolution of two Al-based alloys after cold rolling have been studied in this thesis. An Al-Sc alloy containing shearable Al3Sc nanoprecipitates and Al-TiB2 composite containing non-shearable TiB2 nanoparticles are investigated, respectively. Transmission electron microscopy (TEM), electron backscatter diffraction (EBSD) and neutron diffraction texture analysis are employed to characterize the microstructure and texture development of the two alloys during cold rolling.Dynamic recovery has been inhibited in the matrix containing both shearable (Al3Sc) and non-shearable (TiB2) nanoparticles due to the pinning effects. Hence, few dislocation cells are generated in these matrices that impedes the grain refinement.The development of rolling texture is retarded by either shearable nanoprecipitates or non-shearbale particles. Obvious residual Cube orientation bands are found in materials containing shearable precipitates at the deformed states due to the limitation of cross-slip. Volume reduction of rolling texture components occurs in materials containing large non-shearable particles (about 1 micrometer) due to the recrystallization at PDZs (Particle Deformation Zones), which contributes to grain refinement.In addition, the shearing of nanoprecipitates promotes planar slip leading to strong strain localization and the occurrence of shearbands. The generation of shearbands is orientation dependent and results from the sudden change of deformation paths and inhibition of dynamic recovery. The non-shearable nanoparticles probably have rotated together with the surrounding matrix, which could be a new deformation mechanism
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Salomatina, Y. V., L. A. Smirnova, A. V. Markin, A. P. Aleksandrov, and N. M. Bityurin. "Preparation and properties of hibryd organic-inorganic composites baced on poly-Ti02." Thesis, Sumy State University, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20593.
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Optically transparent hybrid organic-inorganic copolymers based on the poly-
TiO2, vinyl monomers and lactide or glycolide have been prepared. Optical and physi-
cal-mechanical properties of composites are depended with the ratio of components have
shown. Hybrid copolymers possess photochromic properties. By the UV light excitation
reversible darkening of the samples due to the transition Ti
4+
ļ Ti
3+
had observed. The
speed of transition depends on the copolymer composition.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/20593
8
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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Jones, Alan Hywel. "Synthesis and tribology of Sialon/TiB2 ceramic composites." Thesis, University of Warwick, 1997. http://wrap.warwick.ac.uk/56017/.
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The inclusion of TiB2 particles in a Si3N4 or sialon matrix has the potential to improve the materials properties over those of the Si3N4 alone. The combination of the excellent properties of sialon and the high hardness of the TiB2 makes these materials potentially suitable for tribological applications. This research has investigated the use of chemical reactions that can take place during sintering to synthesise TiB2 from TiN and BN. The reactions not only produce TiB2 but simultaneously synthesise the matrix material. The sialon matrix is used as a flexible receptor for excess nitrogen and oxygen. Using such reactions, sialonlTiB 2 composites were successfully produced by both hot pressing and pressureless sintering. It was shown that these materials achieve densities close to the theoretical and contain only the required phases of TiB2 and ~ sialon. Pressureless sintered materials also contain residual sintering aid as an intergranular phase. The composites wee characterised with respect to their microstructure, hardness, fracture toughness and tribological properties. A specially designed wear test apparatus was constructed for the tribological testing. The pin-on-disc apparatus was capable of testing the small volumes of material (minimum diameter of disc ~ 15mm) typically produced at the development stage. The materials were found to have high hardness and reasonable fracture toughness which was attributed primarily to the properties of the matrix phase with some possible toughening from the presence of TiB 2 . Tribological testing revealed high dry sliding coefficients of friction (Jl) for the composites sliding on themselves and reasonable values for the wear coefficient (k) were measured. Wear was found to be dominated by tribochemical reactions forming tribofilms which act to reduce wear of the disc. However, the presence of TiB2 was not seen to contribute directly to the tribological properties of these materials and the usefulness of this type of composite is questioned.
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Cledat-Schneider, Sandrine. "Elaboration et propriétés de composites particulaires AlN-TiB2." Limoges, 1997. http://www.theses.fr/1997LIMO0028.
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Dans le but d'evaluer puis d'optimiser leurs proprietes, des composites ceramiques particulaires aln-tib#2 denses (d#r>99 %) ont ete elabores, sans utilisation d'ajout de frittage, par compression isostatique a chaud de melanges de poudres de nitrure aln et de borure tib#2. L'etude des proprietes thermomecaniques et elastiques a permis de selectionner une composition (tib#2 : 75 mol. % ; aln : 25 mol. %) presentant a l'ambiante des caracteristiques mecaniques optimales. L'utilisation de poudres commerciales de plus faible granulometrie ameliore la resistance a la rupture a l'ambiante et la valeur de 620 mpa est conservee jusqu'a 1100c. Le comportement au fluage en flexion de ce materiau est gouverne par la cavitation. La tenue aux chocs thermiques est toutefois limitee a 340c. La seconde partie concerne l'elaboration d'un composite equimolaire aln-tib#2 dense par reaction exothermique entre une poudre de diborure d'aluminium alb#2 et une poudre de nitrure de titane tin, puis densification. La microstructure est fine et homogene, la taille des grains n'excede pas le micrometre. Les proprietes sont tres faiblement ameliorees par rapport au cas precedent. Enfin, la reactivite des materiaux monolithiques aln et tib#2 et celle du composite equimolaire aln-tib#2 ont ete etudiees par analyse thermogravimetrique en regime dynamique d'oxygene. Le composite equimolaire presente une resistance a l'oxydation intermediaire entre celle du diborure de titane qui debute a 700c et celle du nitrure d'aluminium qui commence a 1000c par la formation d'une phase oxynitrure (al#1#0n#8o#3) precedant celle de l'alumine-. Le piegeage in situ d'une partie de l'oxyde b#2o#3 par le nitrure d'aluminium ou l'alumine conduit a la formation d'aluminoborates al#4b#2o#9 et al#1#8b#4o#3#3, ce qui diminue tres fortement la production des vapeurs corrosives de sesquioxyde de bore qui, dans le cas du borure pur, sont observees des 900c.
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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’eauThis 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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Sand, Sara Catherine. "TiO2/CNT Composite Electrodes in Dye-Sensitized Solar Cell Electrodes." Ohio University Honors Tutorial College / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1492721176795399.
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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'eauThe 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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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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Duddukuri, Ramesh. "SYNTHESIZING AND CHARACTERIZATION OF TITANIUM DIBORIDE FOR COMPOSITE BIPOLAR PLATES IN PEM FUEL CELL." OpenSIUC, 2012. https://opensiuc.lib.siu.edu/theses/862.
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This research deals with the synthesis and characterization of titanium diboride (TiB2) from novel carbon coated precursors. This work provides information on using different boron sources and their effect on the resulting powders of TiB2.The process has two steps in which the oxide powders were first coated with carbon by cracking of a hydrocarbon gas, propylene (C3H6) and then, mixed with boron carbide and boric acid powders in a stoichiometric ratio. These precursors were treated at temperatures in the range of 1200-1400° C for 2 h in flowing Argon atmosphere to synthesize TiB2.The process utilizes a carbothermic reduction reaction of novel carbon coated precursor that has potential of producing high-quality powders (sub-micrometer and high purity). Single phase TiB2 powders produced, were compared with commercially available titanium diboride using X-ray diffraction and Transmission electron microscopy obtained from boron carbide and boric acid containing carbon coated precursor.
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Nguyen, Hoang Nam. "Creating nano composite TiO2.Fe2O3/laterite material applying to treat arsenic compound in groundwater." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-176920.
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This article presents nano composite TiO2.Fe2O3/laterite materials, which were successfully prepared by hydrometallurgical method. The materials were modified using urea as the nitrogen source. The particles size of the materials is from 20-30 nanometers. The obtained materials can not only absorb arsenic compounds but also enhance the ability of converting As (III) or As (V) into Aso, which is removed from solution. Arsenic removal efficiency of these materials is high. Using sunlight in a hydraulic retention time, about 180 minutes, the arsenic value at the inflow was about 10 mg/L but the outflow was negligible. Covering TiO2.Fe2O3 nano on laterite have brought high economical efficiency, on one hand, it saved material and on the other hand, it can be continuously operated without the centrifugal separation of the nano materialBài báo này giới thiệu về phương pháp điều chế vật liệu nano TiO2.Fe2O3 biến tính nitơ được phủtrên đá ong bằng phương pháp thủy luyện. Vật liệu nano thu được có kích thước 20-30 nm. Vật liệu thu được không những có khả năng hấp phụ các hợp chất của asen mà còn có khả năng khử As (III) hoặc As (V) thành Asokhi được chiếu sáng. Sử dụng ánh sáng mặt trời chiếu vào hệ thống xử lý trong thời gian 180 phút có thể loại bỏ được gần như hoàn toàn asen ra khỏi nước mặc dù hàm lượng đầu vào là 10 mg/l. Việc phủ vật liệu TiO2.Fe2O3 nano lên đá ong đã mang lại hiệu quả kinh tế cao, một mặt nó tiết kiệm được vật liệu, mặt khác, vật liệu có thể sử dụng một cách liên tục mà không cần phải tách bằng phương pháp ly tâm
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Ocampos, Fabiana. "Estudo das propriedades eletro- e fotoeletroquimicas do composito TiO2/PPi." [s.n.], 2002. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248665.
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Orientadores: Marco-Aurelio De Paoli, Wilson Antonio Gazzote JuniorDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica
Made available in DSpace on 2018-08-03T16:22:25Z (GMT). No. of bitstreams: 1 Ocampos_Fabiana_M.pdf: 3415385 bytes, checksum: a2d6bd492c5e8aebd61a85274180b576 (MD5) Previous issue date: 2002
Mestrado
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Cheng, Man Fai. "Wear properties of Al-based composites reinforced with in-situ TiC and TiB2 particulates." access abstract and table of contents access full-text, 2004. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b2117409xa.pdf.
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Thesis (M.Sc.)--City University of Hong Kong, 2004.At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Aug. 31, 2006) Includes bibliographical references.
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Changizi, Ahmad. "Production And Properties Of In-situ Aluminum Titanum Diboride Composites Formed By Slag-metal Reaction Method." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12605914/index.pdf.
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In this study, production and properties of titanium diboride particle reinforced aluminum matrix composite were investigated. TiB2 particles form in-situ through the reaction of TiO2 and H3BO3 and Na3AlF6 in aluminum melt. The results showed that the in-situ TiB2 particles formed were spherical in shape and had an average diameter of 1mm .Moreover, the distribution of TiB2 particles in the matrix were uniform. The ultimate tensile strength, yield strength, flexural stress and hardness were found to while reduction in area and elongation were found to decrease with increase in reinforcement content in the matrix.
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Serdarli, Osman. "A Study On The Production And Properties Of In-situ Titanium Diboride Particulate Reinforced Aluminum A 356 Alloy Composite." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613380/index.pdf.
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TiB2 particle reinforced aluminum matrix composites have been the subject of several investigations. An M.Sc. thesis on production of TiB2 reinforced aluminum composites by reaction between liquid aluminum and B2O3 and TiO2 dissolved in cryolite has been completed in this Department in 2005. This study is a continuation of the mentioned M.Sc.study. Composition of the starting cryolite-B2O3-TiO2 system, temperature and time were used as experimental variables. The resulting composite was squeeze cast and its microstructure was examined. Mechanical properties of the produced composite were measured and how mechanical properties of the composite vary with TiB2 content of the composite was determined.
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Li, Zhelun. "Fabrication and VMD Performance of TiO2 Nanocomposite PVDF Membranes and PVDF-PTFE Composite Membranes." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37900.
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In this study, two different strategies were carried out to modify the polyvinylidene fluoride (PVDF) distillation membrane for desalination. The first strategy was the addition of TiO2 nanoparticles into the target membranes and a synergistic effect of hydrophilic and hydrophobic nanoparticles was found for the first time in this work. And the other strategy was the introduction of another polymer material, polytetrafluoroethylene (PTFE), to the PVDF membranes to fabricate a flat sheet PVDF-PTFE composite membrane and this is the first attempt that such a membrane to be made. Two types of membranes were characterized by scanning electron microscopy (SEM) detection, porosity measurement, energy dispersive X-ray spectroscopy (EDX), Attenuated total reflectance (ATR)-Fourier transformed infrared spectroscopy (FTIR), contact angle (CA) measurement, atomic force spectroscopy (AFM) detection and liquid entry pressure of water (LEPw) measurement. Their performance was evaluated by vacuum membrane distillation (VMD) experiments. And the best VMD pure water permeate flux of the membranes fabricated under these two modify strategies could achieve 4.26 kg/m2h (M-L5-B2) and 5.61 kg/m2h (M-40), respectively, when that of pure PVDF membrane is only 0.71 kg/m2h. The salt rejection of the prepared composite membranes are all stably higher than 99.5% which demonstrate their capacity for desalination.
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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-chimiquesNowadays, 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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SINGH, JEETESHWAR. "FABRICATION AND MECHANICAL CHARACTERIZATION OF HYBRID AA6063/RED MUD/TI02 COMPOSITE." Thesis, 2021. http://dspace.dtu.ac.in:8080/jspui/handle/repository/19117.
Full textAbstract:
Composite materials are produced by adding two or more materials together. The
materials that are included in composite have unique physical or chemical properties
individually but when they are mixed together, the produced material has different
properties unlike to individual elements.Aluminum Metal Matrix Composites
(AMMC’s) are most popular composite material used in wide sectors such as
automobiles, defense, aerospace etc. due to its properties like hardness, low density,
non-magnetic, low maintenance and many more. AMMC’s are fabricated using
various processes such as stir casting, diffusion bonding and Power Metallurgy (PM)
process. Amongst all, stir casting is most economical and simpleprocess.
Red mud is the waste by-product during the production of alumina from bauxite by
the Bayer’s process. It is insoluble waste produced due to digestion of bauxite at high
temperature and pressure. Utilization and disposal of red mud is a major
environmental concern. To overcome that red mud is used as reinforcement in MMC
(Metal Matrix Composite). Using red mud as reinforcement with Aluminum matrix
improves the hardness of the Matrix Composite and shows the Composite
characteristics.
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Wu, Jau-Yi, and 吳昭儀. "Synthesis of Antibacterial TiO2/PLGA Composite Biofilms." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/87942015477205113799.
Full textAbstract:
碩士國立中興大學
生醫工程研究所
101
The main purpose of this study was to develop a TiO2/PLGA composite biomaterial for artificial dressing applications. Hydrothermal method and Sol-gel method were used for the preparation of anatase phase of nano TiO2 powder. E. coli and S. aureus were used as biological indicators for the disinfection efficiency of the proposed TiO2/PLGA composite. Various concentration ratios of TiO2 verse PLGA were implemented to optimize the disinfection efficiency of the composite biomaterial. Cell seedings of HaCaTs, L929s, and BECs on the TiO2/PLGA composite biofilms were conducted to evaluate the feasibility of the TiO2/PLGA composite biomaterial on wound healing applications in vitro. The feasibility biocompatible biofilm was further assessed by rat subcutaneous implantation to investigate the histological effect in vivo. The results illustrated that Sol-gel method could prepare anatase phase of nano TiO2 powder. TiO2/PLGA composite biofilms containing 10% of TiO2 nanoparticles revealed an effective antibacterial property, kept well survival rate on HaCaTs and L929s growth, and showed relative safe stability on tissue implantation. Although the biofilms containing 10% TiO2 nanoparticles illustrated good biocompatibility on HaCaTs and L929s, it also expressed certain cytotoxicity on BECs. Therefore, TiO2/PLGA composite biofilms containing 10% of TiO2 nanoparticles was more suitable on less-endothelial cells tissue, such as epidermis of skin.
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Huang, Ching Jeng, and 黃敬任. "Electroplating of Nano Ni-Fe-TiO2 Composite." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/16082889493398367985.
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碩士國立交通大學
材料科學與工程系
90
This research aims to fabricate Ni-Fe-TiO2 composite coating by adding inert nano particle ,TiO2, into Ni-Fe plating bath and electroplated with puls current . Items studied included the distribution of nano TiO2 in Ni-Fe-TiO2 composite coating the mechanial property、crystallization orientation and electrochemiscal property of the composite coating to obtain the optimum electroplating parameters for manufacturing micro-mold. Taguchi method was employed high-aspect-ratio using in UV-LIGA process . The dispersion of nano TiO2 in the coating could be improved by using physics and chemical methods . In our experiment ,although the sodium 2-ethylhexyl sulfate was using as an wet agent ,it can also improved the dispersion of nano size TiO2 in Ni-Fe plating bath. The microhardness of Ni-Fe-TiO2 composite was about 800Hv, which was better than the 580 Hv of the Ni-Fe alloy. The composite interal increased stress with the TiO2 volume percent in the Ni-Fe-TiO2 composite .
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SU, SIN-YU, and 蘇芯褕. "Photocatalysis of Sulfadiazine by Graphene/TiO2 Composite Photocatalysts." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/rv5j7p.
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碩士國立高雄第一科技大學
環境與安全衛生工程系碩士班
105
This study investigated liquid-phase photocatalysis of sulfadiazine(SDZ) by both titanium dioxide (TiO2) and graphene doped TiO2 (GR/TiO2) thin-film. The thin-film photocatalysts were prepared with an electrophoretic deposition (EPD) technique by immobilizing P-25 TiO2, with various amount of GR, onto pure titanium (Ti) metal plates. This study explored the effects of preparation recipes on the photocatalytic activities of prepared samples, which were determined by the degradation rate of SDZ assisted by the prepared samples irradiated with a near-UV light. Several preparation parameters including applied DC biases (15~35 V), and terminal calcination temperatures (250~450℃) for the samples were evaluated. The study also used SEM and XRD to identify surface morphology, and crystal phase of prepared samples. Selected photocatalysts with better activities were further used for conducting SDZ photocatalytic degradation tests in variation pH levels and light sources. The results showed the photocatalysis of SDZ following pseudo first-order reaction kinetics. A better photocatalytic activities of prepared samples were achieved when the they were prepared with calcined in a 450℃ oven. Among them, TG0.5 photocatalyst has the highest activity (k = 0.348 hr-1), which is 13.7 % higher than that of TiO2 photocatalyst. In addition, the effect of EPD of DC biases on the degradation rate of SDZ, the photocatalytic activity of TiO2 increases with the increase of EPD of DC biases, with the highest activity at 35 V. The TG series of photocatalyst, it will be in a EPD of DC biases, with the fastest response rate, which are: TG0.5 (25 V), TG1.0 (20 V), TG1.5 (20 V). Based on the above results, it can be found that the calcination temperature is 450 ℃ with the highest activity, and different series of photocatalyst also has the best EPD of DC biases, can be assembled with a high activity of the photocatalyst, in order: 450TiO2-35V, 450TG0.5-25V, 450TG1.0-20V, 450TG1.5-20V. Finally, the effects of different light sources and pH values on degradation rate of SDZ were investigated. According to the experimental results, it was found that the degradation rate was the fastest and the proportion of pollutants adsorbed by the catalyst at pH= 3. In addition, the TiO2 photocatalyst itself is very poor for the visible light absorption capacity. The experimental results show that the photocatalyst doping of graphene can not only increase the activity of the original TiO2 photocatalyst, but also increase the absorption of the visible light source. Finally, the photocatalyst prepared in this study has the highest activity in UV light and LED light with photocatalyst doped with 0.5% graphene.
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Chang, Ching-Min, and 張景閔. "Research on P3HT/CdSe/TiO2 Composite Solar Cell." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/79218812049197965634.
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博士南台科技大學
機電科技研究所
99
This study presents the manufacturing processes and feasibility of multilayer structured P3HT/CdSe/TiO2 solar cell. The conception was to utilize the matching of energy band gap between the titanium dioxide (TiO2), cadmium selenium (CdSe), and organic dye P3HT to broaden the absorbable range of sunlight spectrum and produce the effective current in the solar cell. The studied items are: (I) Summarizing the suitable manufacturing parameters for each layer of thin film by the experimental results, (II) Analyzing the effect of target to substrate distance by sputtering on the thin film deposition process, (III) Analyzing the effect of substrate temperature and thickness of thin films to the type of crystallization, surface morphology, and photoelectric characteristics of TiO2 and CdSe, (IV) Analyzing the photoelectric properties of organic dye P3HT and aluminum thin films, (V) Discussing the feasibility of four kinds of structured solar cells. From literature reports, both CdSe and organic dye P3HT had the absorbable characteristics within the range of visible light; as if they and TiO2 were combined the solar cells would be achieved due to their match able energy band gaps. Based on this principle, four structured solar cells including P3HT/TiO2, CdSe/TiO2, P3HT/CdSe and P3HT/CdSe/TiO2 were designed, and then the suitable manufacturing parameters for each layer of the thin films by measuring and analyzing for the designed solar cells were investigated. By using different manufacturing parameters, sputtered thin films of TiO2, CdSe, and spraying on spun thin film of P3HT were fabricated. According to the experimental results, the TiO2 thin film with thickness of 500 nm deposited at target to substrate distance of 5 cm under 200 oC, had rougher surface, suitable spectrum absorbance (below 380 nm) and energy band gap. The CdSe thin film with thickness of 900 nm deposited at target to substrate distance of 3 cm under 25 oC had better absorption from visible light (below 730 nm) and smallest energy band gap. The P3HT thin film with thickness of 70 nm spun at room temperature had better flatness and absorption from visible light (450 nm-650 nm). All four types of structured solar cells had absorption ability in range of visible light, especially for the CdSe added thin films were more obvious, and the best absorption was found for P3HT/CdSe/TiO2. Moreover, all four types of structured solar cells generated Current-Voltage curves, the CdSe/TiO2 showed the better photoelectric conversion efficiency.
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Yang, Hung-Hsien, and 楊紘先. "Wet-chemical routes to ZnO / TiO2 composite nanostructures." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/81998166572046046210.
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碩士國立成功大學
化學工程學系碩博士班
96
Syntheses of versatile ZnO and ZnO/TiO2 nanocomposites have been performed using various two-step methods in this study. The fist step for all nanocomposites is the formation of the ZnO nanowire (NW) arrays on indium tin oxide (ITO) substrates using chemical bath deposition. Then the syntheses of ZnO nanoparticles (NPs), ZnO nanobranches or TiO2 NPs on/within the ZnO NW arrays are conducted further using various wet-chemical routes. Hydrothermal syntheses of the 3-dimensional sheet-like ZnO nanostructures and the ZnO films on the top of the ZnO NW arrays have been achieved using HMTA and Zn(Ac)2 at 150 and 230 oC, respectively. On the other hand, using NH4OH and Zn(Ac)2, the formation of the branch-like ZnO nanocompsoites is achievable by solvothermal method. It was also found that the ZnO nanodisks are able to be formed around the NWs by using ethanol as solvent and controlling the reactor pressure during the solvothermal process. Moreover, well-aligned ZnO/ZnTiO3 core-shell NWs with various shell thicknesses have been successfully formed on the ITO substrates when adjusting the H2O concentration in TBOT/AA/ethanol solution using sol-gel method in the second step. Growth of TiO2 within the interstices of the ZnO NW arrays is achievable as well by varying the TBOT concentrations. PEG has been added into the solution for the formation of the ZnO NW/TiO2 NP composite films as well. The effects of the solvent on the formation of the ZnO NW/TiO2 NP composite films have been investigated in this study. It reveals that ZnO NW/TiO2 NP composite films with fewer cracks could be formed on ITO substrate by using tert-buthanol as solvent in the sol-gel process.
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Liu, Yi-You, and 劉伊祐. "Application of Superparamagnetic Poly(methyl methacrylate)/TiO2 Composite." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/81766858149891111183.
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碩士國立高雄應用科技大學
化學工程系碩士班
95
The nano-sized oleic acid-coated magnetite particles (OMP) and its magnetic poly(methyl methacrylate) (PMMA) microspheres were successfully prepared via co-precipitation method and suspension polymerization method, respectively. The nano-sized OMP mixed with methyl methacrylate (MMA) monomers and divinylbenzene were employed to produce the magnetic PMMA microspheres. The morphology and size of magnetic PMMA microspheres and OMP were observed by transmission electron micrograph (TEM), scanning electron microscopy (SEM), and particle size analyzer. The inorganic substance composition and magnetite content of magnetic PMMA microspheres and OMP were observed by wide angle x-ray diffraction (WAXD), and thermogravimetric analysis (TGA). The hysteresis loop, residual magnetism, and coercive force of magnetic PMMA microspheres and OMP were observed by superconductor quantum interference device (SQUID). Application of magnetic PMMA microspheres with titanium dioxide coated surface to degradation of p-phenylenediamine (PPD).
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YANG, KUN-LIN, and 楊坤霖. "Printing of TiO2 Composite Electrodes for Glucose Sensing." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/5x6mu6.
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碩士國立高雄應用科技大學
機械與精密工程研究所
104
Along with the global human civilization, technology development, changes of the daily life in lifestyle and diet, chronic diseases have emerged and increased globally, in which diabetes is one of them. Consequently, diagnosis of diabetes using glucose biosensors is becoming more convenient and rapid, requiring fewer sample. The glucose biosensor technology is developed toward convenient detection providing us with portable tools and accurate analysis data at short time. In the study, a new three-dimensional glucose biosensor is developed by inkjet printing technology. It has advantages of positioning and droplet control, in which the material properties of the printed ink can be changed with different thickness and density. Changing printing parameters without additional patterning masks, the size or shape of the electrode can be altered and produced quickly. Using porous titanium dioxide sintered at high temperature enzymes can be adsorbed into the porous structure. And the titanium dioxide layer is increased with surface area, to allow the enzyme sufficient contacting area for chemical reaction. The glucose biosensor with three-dimensional structure has a good sensitivity and linearity. The glucose solution of different concentrations was added into its reaction zone to show experimental results that the electrochemical signal output increased via the increase of glucose concentration.
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CHEN, HSI-CHENG, and 陳璽丞. "Optoelectronic Properties of SnS-Graphene-TiO2 Composite Photodetector." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/z87vw3.
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碩士國立中正大學
光機電整合工程研究所
107
Graphene has a relatively high carrier mobility and a broad absorption wavelength, and is suitable for use as a photodetector. However, due to the high transmittance of graphene and the fast recombination speed of the carrier, the light response is weak. In this study, a sol-gel method (Sol-Gel) was used to formulate a TiO2 solution, and uniformly spin coated on a glass substrate, then high temperature sintering to form a TiO2 film, and then transfer the graphene grown by chemical vapor deposition. Increasing the light absorption of graphene in the ultraviolet band by TiO2 film and enhancing its responsivity. Due to the energy gap of the material, the response of titanium dioxide in the visible light range is weak. Therefore, the tin sulfide film is deposited on the graphene by chemical bath deposition, thereby enhancing the response of the titanium dioxide to visible light, and exploring the optoelectronic properties of the optimized parameters of the two materials. Finally, the experimental results show that the composite material has a response in the visible light band, which proves that the growth of titanium dioxide on graphene improves the disadvantage of graphene, and the deposition of tin sulfide also improved the problem of TiO2 having no photo-response after visible light.
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Chiu, Zih-Rong, and 邱姿蓉. "Photoelectrocatalysis of MtBE vapor via TiO2 and TiO2/CuO composite thin-film photocatalysts." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/64299926983027452281.
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碩士國立高雄第一科技大學
環境與安全衛生工程研究所
102
Photocatalytic oxidation processes are often applied to control volatile organic compounds (VOCs), which use semiconductor oxides as photocatalysts to yield electron-hole pairs on their surfaces while irradiated with suitable light energy. Producing highly reactive species, such as, hydroxyl and superoxide radicals is considered as key mechanisms for fast degradation of hazardous air pollutants (HAPs). But, due to the fast recombination of the electron-hole pairs, the degradation rates of many VOCs are not high enough and have low quantum efficiencies. Accordingly, this study aimed to develop a gas-phase photoelectrocatalytic reaction process by providing additional biases to photocatalytic oxidation processes for achieving low recombination rates of electron-hole pairs and high degradation rates of VOCs. Other than preparing various kinds of photocatalysts with different characteristics, several affecting factors including reaction temperature, water vapor content, applied biases were also evaluated in this study. Methyl tert-butyl ether (MtBE) was tested as a target compound in this research. The experimental results demonstrated a higher MtBE degradation rate achieved in external bias assisted photocatalytic reactions than in no bias assisted ones. The degradation of MtBE in these reactions followed a pseudo first-order reaction kinetic. For the effects of operation conditions, the MtBE degradation rate increased with reaction temperature and humidity initially, but it declined for further increasing temperature and humidity. Similar reaction patterns were also observed for the effects of the external bias on the degradation rate of MtBE. All of these results indicated the adsorption phenomena dominantly affect the photocatalytic degradation rate of MtBE. Both increase in temperature and humidity can enhance surface reaction rate of MtBE on TiO2, but reduce the adsorption of MtBE by TiO2. As a result, while temperature and humidity changing, peak reaction rates for MtBE were detected due to the compromised results of enhanced surface reaction rate but reduced adsorption rate for MtBE. Two kinds of thin-film photocatalysts, pure TiO2 and CuO-composited TiO2, were prepared in this study. The later one kept high activities while using visible light as light sources, but the former one had higher photocatalytic activities than the later one wile irradiated with near-UV light. In addition, due to more photo-generated electrons transported away from catalysts and their electron-hole recombination rates were reduced, higher MtBE degradation rates were achieved when the catalysts embedded with less narrow spacing of comb-shape circuits.
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Lee, Yar-Lung, and 李亞龍. "Effects of Electrolysis-Formed TiO2 -particles on Properties of Ni-TiO2 Composite Coatings." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/m73tn6.
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碩士國立臺北科技大學
材料科學與工程研究所
97
The experiment produced composite coating with Ni-base material ingredient and different TiO2 concentration, stirring rate of electrolyzed commercial pure titanium formed TiO2 particles into the electrolyth bath which was used distinct direct or pulse current density, then analyzing the coating of TiO2 particles contents, surface morphology and structure to the effects of microhardness and corrosion resistance. As a result, we found microhardness and corrosion resistance will increase. The result was that TiO2 particles in the composite coatings increasing with average content. Besides, the advantages of the process was using electrolysis could dispersed TiO2 particles into the Electroplating solution with easily change to the particles content and properties. The most important thing was saving the cost of process. Therefore, it will increase the capability of competition in composite plating industry.
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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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Chen, Shih-Yang, and 陳世揚. "Applications of Perfluorosulfonated Composite Membranes onProton Exchange Membrane Fuel Cell 1. Nafion/TiO2 composite membranes2. PTFE/Nafion composite membranes." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/529kzk.
Full textAbstract:
博士中原大學
化學研究所
95
Abstract PartⅠ. Nafion/TiO2 composite membranes for fuel cell applications Three high-purity TiO2 (anatase) powders (TPF6, TBF4, and Tconventional) were prepared by the sol-gel method with/without ionic liquid as template and calcinations at 450 ◦C. These powders were, then, characterized to investigate their differences in morphological properties. Electrochemical performances of the H2/O2 PEMFCs employing the Nafion composite membranes with these three TiO2 powders as fillers were studied over 80-120 ◦C under 50% and 95% relative humidity (RH). The result showed that the order of the fillers effect on the performance at 80 and 90 ◦C was the same as that of the TiO2 filler’s specific surface area (i.e. TPF6＞ Tconventional＞ TBF4＞ P25, a commercially available nonporous TiO2 powder). However, the order between Tconventional and TBF4 was reversed at 110 and 120 ◦C under 50% RH. This indicates that the size and the amount of mesopores, which better confined the water molecules, were significant contributing factors to the performances at the higher temperatures. The best power density obtained under 50% RH at 120 ◦C and a voltage of 0.4 V was from the PEMFC with the TPF6-containing Nafion composite membrane. It was about 5.7 times higher than the value obtained from that with the recast Nafion membrane. Part Ⅱ. PTFE/Nafion composite membranes for fuel cell applications Porous expanded polytetrafluoroethylene (ePTFE) membranes were used as support materials for ePTFE/Nafion composite membranes. The composite membranes were prepared by impregnating porous ePTFE membranes with a self-made perfluorosulfonated ionomer (PFSI) solution. Three ePTFE/Nafion composite membranes with different thickness were prepared in this study. The results of scanning electron micrographs (SEM) and oxygen permeabilities showed that the Nafion resin was distributed uniformly in the composite membranes and plugged the micropores. Besides, a continuous thin Nafion film was observed on the surface of each composite membrane. The resulting composite membranes were mechanically durable and quite thin relative to the commercial Nafion® membranes. In dry conditions, tensile strength of the ePTFE/Nafion composite membranes were larger than that of Nafion® 112 due to the reinforcing effect of the porous ePTFE films. The performances of the PEMFC with the as-prepared ePTFE/Nafion composite membranes were also tested on an in-house system. The results showed that the thinner of the composite membrane the better the cell performance. The best fuel cell performance was obtained from the PEMFC with the thin ePN-1 composite membrane, which was similar to that with Nafion® 112, but higher than that with Nafion® 115.
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Lin, Wei-Lian, and 林緯良. "The TiO2 powder preparation, and the mechanical properties and microstructure of TiO2/Ag composite." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/48149211328412288965.
Full textAbstract:
碩士國立臺灣大學
材料科學與工程學研究所
87
The brittle nature of ceramics is the most serious problem in many applications. To improve the toughness of ceramics, ductile metallic inclusions are introduced into the ceramics. In the present study, homemade TiO2 and commercial TiO2 powder was used to prepare the TiO2/Ag composite. The sintering behavior, microstructure and mechanical properties were investigated. In the first part of the present study, the homemade TiO2 powders were synthesized with the yield above 80% by the thermal hydrolysis of TiCl4 in a mixed solvent of n-propanol and water. The precipitates obtained with an RH ratio (volume ratio of n-propanol to water) of 0 are strongly agglomerated, and larger than that of the agglomerates of the precipitates obtained with an RH ratio of 3. Also, the yield of the RH = 3 precipitates is up to 81% and is much higher than that of the RH = 0 precipitates. The extent of crystallization (anatase phase) of the RH = 3 precipitates is also better than that of the RH = 0 precipitates. Both the RH = 3 and RH = 0 precipitates are nearly spherical and with narrow size distribution. The size of the primary particles and agglomerates is 4 and 25-50nm, respectively. The result of the FTIR (Fourier transformed infrared) spectroscopy showed the chemical interactions are taken place between TiO2 particle surface and n-propanol, which increase the yield and the extent of crystallization of the precipitates and decrease the anatase-rutile transformation temperature of the precipitates. Because of the precipitates of the homemade TiO2 are fine and highly agglomerated. The specimens composed of the as-precipitated TiO2 can not be densified even after sintering at 1300℃ for one hour. By ball milling and AgNO3 coating, the large agglomerates can be destroyed. Then, the relative density of the specimens reaches 97% after sintering at 1300℃ for one hour. The existence of the Ag inclusions inhibits the grain growth of TiO2. The plastic deformation of the Ag inclusions can be observed on the fracture surface of the composites. Therefore, the addition of Ag particles may toughen the TiO2. In second part of the present study, the TiO2/Ag composites were prepared by using a commercial TiO2 powder, which with mean particle size of 1.56m. The composites were prepared by sintering at 1300℃ for one hour. The wettability of the liquid Ag is good to TiO2 matrix. Therefore, with a small addition of Ag particles, the density of composites can be increased. The relative density of the composites containing 7.7vol% Ag is 99.3%. The Ag inclusions inter-connected in the composite when the Ag content is higher than 7.7vol%. The flexural strength is affected by the density and the TiO2 grain size of the composite. However, the flexural strength of all the composites is higher than that of the TiO2 specimens even as the relative density of the composites containing 13.9vol% is only 91.6% (the relative density of the TiO2 specimens is 96.7%). The fracture toughness is affected by the inter-connectivity of Ag inclusions and the inclusion size. The flexural strength and fracture toughness of the composites containing 7.7vol% Ag is respectively 1.4 and 1.9 times that of TiO2 specimens.
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Su, I.-Chen, and 蘇以禎. "Photocatalytic decomposition of acetaldehyde by Zeolite - TiO2 composite sheet." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/88859510947164708176.
Full textAbstract:
碩士中國文化大學
材料科學與奈米科技研究所
94
This study investigated to fabricate Zeolite - TiO2 composite sheets by using a wet papermaking technique for to filter and air-cleaning, and further assess the efficiency of adsorbability photodecomposition for acetaldehyde. Were used single zeolite composite sheets、TiO2 composite sheets、Zeolite - TiO2 composite sheets decomposition for acetaldehyde to compare. Parts of adsorbability for acetaldehyde, when zeolite structure Si／Al molecular ratio to increase to be conducive to reduce acetaldehyde consistency. Si／Al molecular ratio size influence more than surface area size can effective to reduce acetaldehyde consistency. Zeolite manufacture zeolite composite sheets materials, in short hours acetaldehyde consistency have obvious and quickly to reduce, but not have decomposition for acetaldehyde function. Behide adsorbability for acetaldehyde, TiO2 powder and TiO2 composite sheet irradiated with ultraviolet light（UV） can effectively decomposition for acetaldehyde, but absolute to remove for acetaldehyde need spend a lot of time. Zeolite - TiO2 composite sheet irradiated with ultraviolet light and TiO2 composite sheet compare, have quickly and effectively decomposition for acetaldehyde, zeolite composite sheets even though adsorbability for acetaldehyde, when adsorbability to reach balance, incapable adsorbability more acetaldehyde. Parts of adsorbability photodecomposition for acetaldehyde, Zeolite - TiO2 composite sheet（Ti：Ze ＝ 1：2）irradiated with ultraviolet light, in short hours have effectively absolute decomposition for acetaldehyde, low concentration have fairly good to decompose effect, decompose efficiency to reach 95％.
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Huang, Ya-Hui, and 黃雅惠. "Effects of Ag/TiO2 composite nanoparticles on mammalian cells." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/20057048137429884325.
Full textAbstract:
碩士高雄醫學大學
生物醫學檢驗學研究所碩士班
94
Photoexcited titanium dioxide can be used to kill microorganisms by the resulting free radical activity. Nanosized silver/TiO2 composite would enhance the catalytic efficiency of photoexcitation. However, the possible effects resulted from photoexcited Ag/TiO2 nanoparticles on mammalian cells remain to be elucidated. To investigate the photocatalytic cytotoxic effects of photoexcited Ag/TiO2 nanoparticles on mammalian cells, four mammalian cell lines including 293T (human emoryonic kidney) , Vero (Monkey kidney normal cells), A549 (Human lung epithelial of carcinoma cells) and MDA-MB 231 (human breast cancer cells) were tested for cell viability and oxidative damage assay. After exposed the cell to photoexcited Ag/TiO2 nanoparticles for 24 and 48 hours, the cell morphology was examined using transmission electron microscopy and cellular toxic response was measured by measuring cell viability based on trypan blue test. In addition, to assess the extent of oxidative damage, malondialdehyde (MDA) in the cell medium was measured using HPLC method. The results showed that Ag/TiO2 nanoparticles could be observed in the cytoplasma of the four mammalian cellsMoreover, the cell viability of MDA-MB 231 cells decreased significantly (p<0.05) after 24H irradiation of UVC light on the composite nanoparticles of Ag/TiO2 solution for 2 minute, while the viability of Vero cells decreased after 48H irradiation of UVC light on the composite nanoparticles of Ag/TiO2 solution for 14 minute. MDA levels in the suspension of 293T, Vero and MDA-MB 231 cell lines were found to be elevated after irradiation for Ag/TiO2 nanoparticles. In summary, based on the results obtainedthe composite nanoprticles of Ag/TiO2 have potential cytotoxic effects on mammalian cells under UV irradiation.
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Chu, Min-Chia, and 朱敏嘉. "TiO2 Composite Membrane for Fouling Mitigation in MBR Operation." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/81288397300485432659.
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CHIU, HSUAN-YANG, and 邱絢揚. "The study of TiO2 nanorods/nanoparticles hybrid composite photoanode." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/89720014576782197325.
Full textAbstract:
碩士國立臺灣科技大學
化學工程系
97
In this study, hydrothermal method was employed to grow 1-D titanate nanorods, which is annealed at 700oC for 2 hours to transfer 1-D titanate to anatase titanium dioxide (TiO2) nanorods. Difference TiO2 photoanodes were make by mixing TiO2 nanorods and P25 particles and different TiCl4(aq) treated time. In order to find out the optimum mixture condition of TiO2 photoanode, different kinds of TiO2 photoanodes were sensitized with N3 dye. The absorbed amount of N3 dye was analyzed by UV-visible absorption spectroscopy. Based on the optimum condition of TiO2 photoanode, quantum dots sensitized photoanode was studied by using home-made CdSeS quantum dots (QDs). In this study, two different kinds of linker, 3-mercaptoproponic acid (MPA) and 11-mercaptoundecanoic acid (MUA), were used to anchor CdSeS QDs on the surface of TiO2 photoanode. The properties of CdSeS QDs sensitized photoanode were characterized by absorption spectroscopy, photoluminescence and lifetime analysis, the band gap structure of CdSeS and MPA or MUA were decided by cyclic voltammetry (CV), and the cell performances were characterized by incident-photocurrent efficiency (IPCE) and current-voltage (I-V) measurement.
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Chiang, Chin-Yeh, and 江菁燁. "Investigate of nano-particle/tube TiO2 composite polymer electrolyte." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/09965377798185218068.
Full textAbstract:
碩士國立中央大學
化學研究所
91
Nano composite polymer electrolytes are one of the effective approaches to enhance ionic conductivity, mechanical stability and better interfacial contact with electrodes ( i.e., Li metal ) in secondary batteries and other ionic devices. Ion conduction enhancement is higher when filler nano particles in smaller dimensions with high specific surface area. The strong Lewis base characteristics of nano inorganic oxide particles facilitate salt disassociation and physical cross-link with polymer chain improves the mechanical strength. The formation of TiO2 nano-particle and nano-tube were confirmed with XRD、TEM、XPS、TGA. The XPS results are consistent with structure that the fluorine atoms in PVDF and oxygen atoms in inorganic oxide TiO2 are coordinate with the dissociated Li+ ions through acid-base reactions. As evident from SEM micrograph, contents of lithium salt and TiO2 with different scale will affect polymer crystallinity. When polymer electrolyte is swollen with organic solvent, the overall ion conductivity would be governed by the dissociation of salt, and ion mobility governed by the polymer and the plasticizer dielectric constant and the viscosity. On a separate studies of PEO, nano-tube TiO2 surface groups provide cross-link centers for the PEO segments and also for the anions, which reduces the polymer reorganization with higher degree of amorphous in composite electrolytes. Nano-tube TiO2 surface groups also facilitated more complete salt dissociation. Conduction path is established on the nano-tube TiO2 where the charge transport achieved by replacing the nearby vacancy ( the “hole” ) hopping in sequential manner.
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Yang, Che-Hsiu, and 楊哲修. "Application of TiO2/Ni Composite prepared by Electrophoretic Deposition." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/41928489350875075083.
Full textAbstract:
碩士國立雲林科技大學
工業化學與災害防治研究所碩士班
90
A survey on electrophoretic deposition of TiO2/Ni composite by pulse current on stainless steel is given. Many experimental factors (current density, pulse current diameter, stirred speed) were found to influence quality of composite. Scanning electron microscopy(SEM) with an energy dispersive X-ray (EDX) and optical microscopy were carried out to analyze the surface of the film and found the optimal operating condition. E. coli were used to study the bactericidal effect of TiO2/Ni composite, methanol were used to study the degradation of gas. The survival ratio for E. coli in the liquid film on the TiO2 film under black light illumination to a negligible level within 2 h. Experimental data reveal that at 40 mA/cm2, Ton:Toff = 8:1, 150rpm would get better surface morphology and more TiO2. The effects of initial methanol MeOH concentration, ultraviolet (UV) light intensity, MeOH flow rate on the photocatalytic decomposition of MeOH have also been determined. The decomposition of MeOH by photocatalysis increases with lower initial MeOH concentration, lower MeOH flow rate and higher UV light intensity. Key words: electrophoretic deposition, titanium dioxide (TiO2), pulse current, E. coli
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Cheng, Chuan Tse, and 成荃增. "Nano-TiO2 composite Alignment Layers for OCB LCD applications." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/08637828020099200241.
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Liao, Yu Han, and 廖于涵. "Preparation and Photocatalysis of TiO2/Cellulose Nanofibers Composite Films." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/3y2t2u.
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Kao, Shih-Mou, and 高釋懋. "Effect of seeding to crystallization of solvothermally prepared anatase TiO2 and TiO2/Ag composite particles." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/21693247780997689457.
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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.
Full textAbstract:
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.
Full textAbstract:
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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Bucevac, DUSAN. "Microstructure-Mechanical Properties Relations in Pressureless Sintered SiC-TiB2 Composite Ceramics." Thesis, 2009. http://hdl.handle.net/1974/5266.
Full textAbstract:
Abstract
Densification and mechanical properties (hardness, fracture toughness and flexural strength) of the SiC-TiB2 composite were studied. Pressureless sintering experiments were carried out on samples containing 0 to 50 vol % of TiB2 created by an in-situ reaction between TiO2 and C:
2TiO2 + B4C + 3C 2TiB2 + 4CO
Al2O3 and Y2O3 were used as sintering additives to create a liquid phase and promote densification at sintering temperatures ranging from 1820 to 1940oC. The sintered samples were subsequently heat-treated at temperatures ranging from 1850 to 1970oC
It was found that the presence of TiB2 formed by the above reaction serves as an effective obstacle to crack propagation thus increasing both the strength and fracture toughness of SiC while maintaining high a hardness of the sintered samples. Densities higher than 98 % TD were achieved depending on both the sintering temperature and heat treatment conditions. From a density viewpoint, the optimum volume fraction of TiB2 was from 12 to 24 vol %. Typical microstructures for samples with this volume fraction of TiB2 consist of TiB2 particles (< 5m) uniformly dispersed in a matrix of elongated SiC plates. The presence of TiB2 particles in the matrix of SiC inhibited exaggerated grain growth of the SiC grains and activated additional toughening mechanisms. The subsequent heat treatment of the sintered samples improved mechanical properties. The optimum sintering and heat treatment temperatures were 1940 and 1970oC, respectively. The maximum flexural strength of 593 MPa was obtained in sample with 12 vol % TiB2. A maximum fracture toughness of 6.6 MPa•m1/2 was measured in samples containing 24 vol % TiB2. While both fracture toughness and strength increased with the presence of TiB2 particles, hardness on the other hand decreased from ~18 GPa in samples without TiB2 to 16.4 and 15.9 GPa in samples with 12 and 24 vol % TiB2, respectively. A theoretical analysis was conducted to model the effect of microstructure on the fracture toughness of SiC-TiB2 composites and was experimentally verified.Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2009-09-30 23:04:32.565
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Yeh, Ji-Chang, and 葉吉昌. "Fabrication of TiO2/Graphene Oxide Composite Nonwoven Fabrics by Electrospraying." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/7798c9.
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Wu, Bi-Ju, and 吳璧如. "Nitrate removal from water by a nano-TiO2-Fe0 composite." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/30957439566364331966.
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碩士國立交通大學
環境工程系所
96
Nano-zero-valent iron (nFe0) and titanium dioxide (TiO2) have been widely applied for the treatment of nitrate in water. However, the treatment produces ammonium (NH4+) as the end product of nitrate reduction, which is another pollutant in water. Moreover, the treatment efficiency is limited by the formation of the metal oxide layer on the nFe0 surface and the recombination phenomenon on the TiO2. Therefore, a nano-TiO2-Fe0 composite (NTFC) material was developed in our laboratory to overcome these problems. The reductive ability of NTFC was first investigated and the feasibility of NTFC treatment for nitrate removal was evaluated. The result showed that at pH 3 and under UV irradiation, the ferrous iron (Fe2+) concentration increased continuously in the NTFC system. Compared with the nFe0 system, the NTFC system performed more effectively in nitrate reduction. In NTFC system, it was found that the nitrate reduction was strongly affected by the pH, NTFC dosage and the ratio of TiO2 and nFe0 in NTFC. The system favored more acidic and higher NTFC dosage. At pH 3 and the NTFC (TiO2: nFe0 = 1:10) dosage of 0.25 g/30 mL, 58% of nitrate was reduced to NH4+ while 37% turned into N2. The higher nitrate removal and N2 conversion rate under this condition was most likely due to the high Fe2+ and H2 generations from the NTFC. In conclusion, the NTFC is feasible for nitrate removal from water with high N2 yield.