Dissertations / Theses on the topic 'Titanium dioxide'
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1
Flinn, C. "Photocatalytic reactions of alchohols on titanium dioxide and platinized titanium dioxide." Thesis, University of Nottingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380187.
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Lagarec, Ken. "Pressure-induced structural modifications in dioxides of group IVB elements: Titanium dioxide, zirconium dioxide and hafnium dioxide." Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/9527.
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Four specific studies are presented in this thesis, regarding the high-pressure phases of the three compounds. ZrO$\sb2$ was studied at pressures of up to 73 GPa using energy dispersive X-ray (EDX) diffraction techniques. The quenched phase was analysed using angle dispersive X-ray (ADX) diffraction with imaging plates, and was identified as having a cotunnite-type structure (space group Pnma) by Rietveld refinement. HfO$\sb2$ was also studied to 72 GPa using EDX diffraction measurements, and its quenched phase was also identified as having a cotunnite-type structure, based on the simularities of its EDX and Raman spectra with those of the quenched phase of ZrO$\sb2$. TiO$\sb2$ was involved in two separate studies. The first is a Raman spectroscopic study up to 73 GPa, starting with anatase. Some EDX diffraction measurements were also taken to pressures up to 105 GPa. Additionally, EDX diffraction measurements of TiO$\sb2$ up to 28 GPa were taken to determine the equations of state of its high-pressure phases, starting with anatase and furtile at atmospheric pressure. (Abstract shortened by UMI.)
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McCormick, John. "Chemistry of titanium dioxide nanoparticles." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 10.93 Mb., 224 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3220706.
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Harrison, Robert William. "Reduction of titanium dioxide photoactivity." Thesis, University of Newcastle Upon Tyne, 2006. http://hdl.handle.net/10443/856.
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Titanium dioxide, "titania" is used for a wide range of everyday applications, such as in sunblocks, paints, paper, and some plastics. For these uses it is necessary to reduce the photoactivity of the titania for either product quality or consumer safety. Titanium dioxide also finds application in the field of photocatalysis for pollution abatement and in this instance a high photoactivity is desirable. This thesis describes the development and characterisation of two main strategies intended to reduce titania photoactivity: the addition of iron dopants to suppress the number of surface radicals (Chapters 3 and 4), and the addition of an organic coating to the titania to scavenge the radicals (Chapters 5 and 6). The titania was iron doped in two ways, either only on the surface, or in the lattice and on the surface (shown by Electron Paramagnetic Resonance "EPW' spectra). The effect of several novel organic coatings on the photoactivity was tested: a phosphate, an organophosphate based coating and an organosilane. Two types of titanium dioxide were modified, a rutile sample used in commercial sunblocks and Degussa P25, a titania commonly used in research. The efficiencies of these strategies were tested by several methods to determine the effect of solution medium on the photoactivity. A new technique of 2-nitrophenol degradation was developed to measured photoactivity in aqueous solutions and compared with the well characterised technique of 2-propanol oxidation. In addition, a test based on salicylic acid degradation was developed and shown to measure the photoactivity by direct hole oxidation. Infra red spectroscopy and surface area determination were used to analyse how the coatings formed on the titania surface. IR spectra show that the headgroups bond to the surface and so the coatings are hydrophobic. Careful analysis showed that organosilanes form on the surface as crosslinked polymers. Lastly, work on 4-nitrophenol degradation carried out under my guidance complements earlier work on 2-nitrophenol degradation to show that UV absorption by the solution affects the measured kinetics of photocatalytic degradation.
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Duncan, Elizabeth Gunn. "Arsenic remediation using nanocrystalline titanium dioxide." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=53330.
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Lussier, Alexandre Francois. "Ferromagnetism in cobalt-doped titanium dioxide." Diss., Montana State University, 2005. http://etd.lib.montana.edu/etd/2005/lussier/LussierA1205.pdf.
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Burg, Tristan Kevin Materials Science & Engineering Faculty of Science UNSW. "Semiconducting properties of polycrystalline titanium dioxide." Publisher:University of New South Wales. Materials Science & Engineering, 2008. http://handle.unsw.edu.au/1959.4/41262.
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Titanium dioxide, TiO2, has potential applications as a photoelectrode for photoelectrochemical generation of hydrogen by splitting water using solar energy and as a photocatalyst for water purification. This study is part of the UNSW research program to process TiO2-based oxide semiconductors as high-performance photoelectrodes and photocatalysts. This study investigates the effect of defect disorder on semiconducting properties of polycrystalline TiO2. This study involved the processing of high-purity polycrystalline TiO2 and determination of its semiconducting properties through measurement of electrical conductivity and thermoelectric power at elevated temperatures (1073-1323K) in controlled oxygen activities [1x10-13 Pa < p(O2) < 75 kPa]. The study included two types of experiments: Determination of electrical properties under conditions of gas/solid equilibrium. The data obtained was used to derive defect disorder and related semiconducting properties Monitoring of electrical properties during equilibration. This data was used to determine the chemical diffusion coefficient. The data obtained under equilibrium conditions indicates that oxygen may be used as a dopant to impose controlled semiconducting properties. In reduced conditions TiO2 is an n-type semiconductor and under oxidizing conditions TiO2 is a p-type semiconductor. The n-type behaviour is associated with oxygen vacancies as the predominant defects and titanium interstitials as the minority defects. The p-type behaviour is closely related to titanium vacancies that are formed during prolonged oxidation. Charge transport at elevated temperature was shown to involve substantial contribution from ions. Analysis of electrical properties enabled determination of several defect-related quantities including the activation enthalpy for oxygen vacancy formation, and the activation energy of the electrical conductivity components related to electrons, holes and ions. The kinetic data obtained during gas/solid equilibration enabled determination of the chemical diffusion coefficient which exhibited a complex dependence on nonstoichiometry. In addition, prolonged oxidation showed that equilibration occurred in two kinetic regimes. One for highly mobile oxygen vacancies and titanium interstitials which quickly reached an ??operational equilibrium?? within hours and another slow kinetic regime for equilibration of titanium vacancies over many thousand hours. The determined chemical diffusion coefficient data may be used to select the processing conditions required to impose uniform concentration of defects within a TiO2.
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Cai, Yanling. "Titanium Dioxide Photocatalysis in Biomaterials Applications." Doctoral thesis, Uppsala universitet, Nanoteknologi och funktionella material, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-160634.
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Despite extensive preventative efforts, the problem of controlling infections associated with biomedical materials persists. Bacteria tend to colonize on biocompatible materials and form biofilms; thus, novel biomaterials with antibacterial properties are of great interest. In this thesis, titanium dioxide (TiO2)-associated photocatalysis under ultraviolet (UV) irradiation was investigated as a strategy for developing bioactivity and antibacterial properties on biomaterials. Although much of the work was specifically directed towards dental materials, the results presented are applicable to a wide range of biomaterial applications. Most of the experimental work in the thesis was based on a resin-TiO2 nanocomposite that was prepared by adding 20 wt% TiO2 nanoparticles to a resin-based polymer material. Tests showed that the addition of the nanoparticles endowed the adhesive material with photocatalytic activity without affecting the functional bonding strength. Subsequent studies indicated a number of additional beneficial properties associated with the nanocomposite that appear promising for biomaterial applications. For example, irradiation with UV light induced bioactivity on the otherwise non-bioactive nanocomposite; this was indicated by hydroxyapatite formation on the surface following soaking in Dulbecco’s phosphate-buffered saline. Under UV irradiation, the resin-TiO2 nanocomposite provided effective antibacterial action against both planktonic and biofilm bacteria. UV irradiation of the nanocomposite also provided a prolonged antibacterial effect that continued after removal of the UV light source. UV treatment also reduced bacterial adhesion to the resin-TiO2 surface. The mechanisms involved in the antibacterial effects of TiO2 photocatalysis were studied by investigating the specific contributions of the photocatalytic reaction products (the reactive oxygen species) and their disinfection kinetics. Methods of improving the viability analysis of bacteria subjected to photocatalysis were also developed.
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Sjöström, Daniel. "Plasma processing for titanium dioxide coatings." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-199377.
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Cadman, Christopher. "Titanium dioxide nanoparticles for photodynamic therapy." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/titanium-dioxide-nanoparticles-for-photodynamic-therapy(91717f00-c70e-4f07-8921-64caa9290b42).html.
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In the present thesis we propose the development of hybrid polymer titanium dioxide (TiO2) nanoparticles for use in biomedical applications. TiO2 exhibits high biocompatibility in the dark however, upon illumination in aqueous media with near UV light it produces an array of reactive oxygen species (ROS) which have the capability to induce death in neighbouring cells. The process of inducing cell death using a photosensitive material which produces ROS is known as photodynamic therapy (PDT) and is used to treat a wide range of maladies from psoriasis to cancer.We have demonstrated the ability to produce anatase nanoparticles with high control over their resulting size through a novel water mediated sol-gel synthetic method in benzyl alcohol, using either Ti(OnPr)4, Ti(OnBu)4 or Ti(OiPr)4 as the metal precursor. Through dynamic light scattering (DLS) analysis we have shown that the mechanism of nanoparticle growth appears to proceed through the agglomeration of primary nanoparticles formed instantly upon adding the reagents together. After synthesis the nanoparticles could be easily redispersed in aqueous media at pH2 with any further agglomeration being controlled by the parent alkoxide.After synthesis the nanoparticles were coated with PEG, conjugated to either a catechol or phosphate as ligand, in order to stabilise the nanoparticles at neutral pH. Uncoated nanoparticles exhibited good photoactive capability in the photooxidation of methylene blue. However, on coating with catechols the photoactivity of the nanoparticles was abolished. Coating with phosph(on)ates on the other hand preserved or even enhanced the photoactivity which makes this system promising for in vivo applications.At the same time this thesis also reports preliminary investigations on the use of TiO2 embedded into the walls of model drug loaded poly electrolyte multilayer microspheres for UV triggered delivery applications.
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Szczepankiewicz, Steven Henry Hoffmann Michael R. "Surface chemistry of titanium dioxide photocatalysts /." Diss., Pasadena, Calif. : California Institute of Technology, 2001. http://resolver.caltech.edu/CaltechETD:etd-05232006-094537.
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Chen, Qianqian. "Synthesis of Photocatalytic Titanium Dioxide and Nitrogen Doped Titanium Dioxide Coatings Using an Atmospheric Dielectric Barrier Discharge." Doctoral thesis, Universite Libre de Bruxelles, 2018. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/276815.
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In this thesis, we focused on understanding the synthesis of titanium dioxide (TiO2) films and nitrogen doped TiO2 films using an atmospheric pressure Dielectric Barrier Discharge (DBD). The first part of the work was dedicated to the deposition of TiO2 films by cold plasma DBD with titanium tetraisopropoxide as precursor in a single-step process at room temperature. The deposition rate was about 70 nm·min-1. The photocatalytic degradation rate for the degradation of methylene blue (MB) under ultra violet (UV) irradiation of the TiO2 film after annealing was close to a reference anatase TiO2 spin coated film. Moreover, the TiO2 films showed a good photocatalytic stability. The second part of the study focused on the optimization and the understanding of the effect of the plasma parameters (gas flow rate and power) on the morphology of the TiO2 films and on the investigation of the deposition mechanisms. The morphology of the film changed from granular to compact film by either increasing the total flow rate or decreasing the plasma power. In other words, adapting the energy density in the plasma allowed the control of the morphology of the TiO2 films. To our knowledge, it was the first time that the energy density parameters of the plasma were used to control the morphology of TiO2 films. The photocatalytic degradation rate for the degradation of MB under UV irradiation of the annealed TiO2 film turned out to be about 2 and 15 times higher than the one of the commercial TiO2 film and the as-deposited TiO2 films, respectively. In order to extend the light utilization to the visible light range, TiO2 films were doped with nitrogen using a room temperature argon/ammonia plasma discharge. XPS and SIMS results confirmed that the nitrogen has been incorporated in the TiO2 lattice mostly in Ti-N state. This was further confirmed by Raman spectroscopy and XRD. The plasma properties and the doping mechanism were studied by Optical Emission Spectroscopy. It is suggested that the NH radicals played a key role in the doping of TiO2. The concentration of nitrogen in the N-TiO2 coatings could be tuned by adapting the ratio of NH3 in the plasma or the plasma power. The band gap of our N-TiO2 coatings is lower than the one of undoped TiO2 coating. The photocatalytic degradation rate for N-TiO2 coating was more than 4 times higher than the one of the undoped TiO2 coating.Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Oji, Maduagwu Ogbenna. "An investigation of commercially pure titanium and titanium alloy surfaces for use in biomedical applications." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246320.
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Goyal, Amita. "Titanium dioxide-germanium nanocomposites for photovoltaic applications." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file Mb., 104 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1435250.
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Sheeran, Conor P. "Biological responses to nanostructured titanium dioxide surfaces." Thesis, University of Ulster, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526963.
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Breeson, Andrew. "Control of crystallinity in photocatalytic titanium dioxide." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/10037914/.
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Powders and thin films of titanium dioxide (TiO2) were synthesised via wet chemical methods in two ways: a sol-gel synthesis, and a liquid phase deposition. Crystalline mixed phase powders, highly oriented films, and non-crystalline films of titanium dioxide have all been investigated. Specifically this investigation revealed dramatic differences in the XPS valance band spectra of the crystalline polymorphs of anatase and rutile, and subsequently a novel procedure for extracting quantitative phase information from X-ray photoelectron spectroscopy valence band spectra was developed. A linear relationship between the mixed phase TiO2 surface structure determined by this novel technique, and the ensuing photocatalytic activities were discovered. Additionally, highly oriented thin films of TiO2 were synthesised on single crystal substrates. Nitrogen doping of the films was achieved in two ways, and the distribution of the dopant within the films was revealed to be dramatically different for each method. Furthermore, N doping induced a phase transformation from highly aligned rutile to polycrystalline anatase. This result of a rutile to anatase transition at high temperature and not been observed previously. As before, these results were confirmed by X-ray diffraction and X-ray photoelectron spectroscopy valance band analysis. Lastly, non-crystalline, unaligned films of TiO2 on glass substrates were synthesised. The film structure was revealed to be porous, and successively exhibited superhydrophilic abilities without ultraviolet light irradiation. Further investigation via X-ray absorption spectroscopy techniques revealed the films to have anatase-like short range order with a significant tetrahedral titania component. The films were also shown to be highly photocatalytically active. Powders and thin films of titanium dioxide (TiO2) were synthesised via wet chemical methods in two ways: a sol-gel synthesis, and a liquid phase deposition. Crystalline mixed phase powders, highly oriented films, and non-crystalline films of titanium dioxide have all been investigated. Specifically this investigation revealed dramatic differences in the XPS valance band spectra of the crystalline polymorphs of anatase and rutile, and subsequently a novel procedure for extracting quantitative phase information from X-ray photoelectron spectroscopy valence band spectra was developed. A linear relationship between the mixed phase TiO2 surface structure determined by this novel technique, and the ensuing photocatalytic activities were discovered. Additionally, highly oriented thin films of TiO2 were synthesised on single crystal substrates. Nitrogen doping of the films was achieved in two ways, and the distribution of the dopant within the films was revealed to be dramatically different for each method. Furthermore, N doping induced a phase transformation from highly aligned rutile to polycrystalline anatase. This result of a rutile to anatase transition at high temperature and not been observed previously. As before, these results were confirmed by X-ray diffraction and X-ray photoelectron spectroscopy valance band analysis. Lastly, non-crystalline, unaligned films of TiO2 on glass substrates were synthesised. The film structure was revealed to be porous, and successively exhibited superhydrophilic abilities without ultraviolet light irradiation. Further investigation via X-ray absorption spectroscopy techniques revealed the films to have anatase-like short range order with a significant tetrahedral titania component. The films were also shown to be highly photocatalytically active.
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Yiran, Li. "Black Titanium Dioxide: Synthesis, Characterization and Applications." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42653.
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The exploration and application of nanomaterials have been attracting researchers’ attention in recent decades. Nanocatalysts, as one of the very important classes of nanomaterials, have been developed for several generations. Nanotechnology makes light be possibly utilized in catalysis rather than only heat and allows multifunctional parts to be assembled in one catalyst. The TiO2 (as the representative of hetero-photocatalyst) and iron-based magnetic catalysts (as multifunctional catalyst) will be discussed in detail in this thesis.
The first chapter will introduce the background of catalysts and nanomaterials. TiO2, especially black TiO2, will be mainly discussed in the aspects of properties, synthesis, and applications. Another part of the chapter will talk about the separation-friendly catalyst – magnetic heterogenous catalysts’ synthesis and applications.
Chapter 2 focuses on the synthetic route we used and the characterization of black TiO2 catalysts and magnetic catalysts. Both anatase and rutile black TiO2 catalysts were successfully prepared originally from Degussa P25 using the ethanol reduction method. The re-whitening treatment was also examined on both black TiO2 catalysts. All catalysts were characterized and compared by diffuse reflectance (DR), powder X-ray diffraction (XRD), and X-ray photoelectron spectroscope (XPS). Tauc plot results show that black TiO2 has smaller band gap than white TiO2. XPS revealed the existence of surface -OH species and Ti3+ in black TiO2. Furthermore, these two characterization techniques and XRD all proved that the blackening and re-whitening treatment does not change the crystalline phase of the catalysts, and the blackening treatment is reversible. For magnetic catalysts, we synthesized magnetic Fe2O3, Fe2O3@TiO2, copper/iron oxide magnetic TiO2, and black magnetic catalysts. Other than diffuse reflectance spectroscopy, Raman spectroscopy, scanning electron microscopy, and energy-dispersive X-ray elemental mapping analysis were used for determining the light-absorption properties, composition, and morphology of all synthesized magnetic catalysts. In addition, the magnetic separation was also achieved by simply applying an external magnetic field.
Chapter 3 will discuss and compare the decarboxylation reaction activities of pristine, black, and re-whited TiO2 catalysts. The reactions were carried under the UV, blue, red, green, and white light irradiation. Unfortunately, the reaction was found only working under UV-light irradiation. The best solvent was dioxane which may be due to the proton affinity of the oxygen atom in dioxane molecule, which facilitates the deprotonation of the carboxylic acid. The optimal catalyst amount was found as 10 mg per 5 mL reaction mixture, and the kinetic study shows that the reaction is a pseudo-first order reaction. It is a pity that the performance of black TiO2 catalysts is worse than the pristine and re-whitened TiO2.
Chapter 4 will talk about the sol-gel synthesized magnetic catalysts. These catalysts were used for aldehyde-alkyne-amine (A3) coupling reaction. The reaction was tested by light irradiating or traditional heating, but only heating can make the reaction proceed. Results also show that the coupling reaction requires copper to finish. The best solvent was found as toluene and the optimal reaction time is 6 hours at 120 ̊C. Sadly, the reactivity of copper/iron oxide magnetic TiO2 decreases a lot after three reaction cycles because of the copper leaching problem.
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Hong, William Sungil. "Oxidation-reduction kinetics of porous titanium dioxide /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487331541711442.
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Brinkley, David W. "Thermal and photocatalytic oxidation of 2-propanol on rutile titanium dioxide (110) and (100) /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/11605.
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Kang, Chin-Shuo. "CONTROL OF TITANIUM DIOXIDE NANOFIBER CRYSTALLINITY, PARTICLE SIZE AND MORPHOLOGY." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron161960479044817.
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Bolívar, León Rafael [Verfasser]. "Synthesis of titanium powder by magnesiothermic reduction from titanium dioxide / Rafael Bolívar León." Aachen : Shaker, 2019. http://d-nb.info/1188550675/34.
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Soysal, Kaan. "Photocatalytic Activity Of Apatite-deposited Titanium Dioxide Powder." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611820/index.pdf.
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Apatite was formed on the surface of titanium dioxide (TiO2) powders by a biomimetic process. The deposition was accomplished by immersing TiO2 powders in simulated body fluid (SBF) for 1, 3, 6, 12, and 24 h. SBF used throughout this study had calcium and phosphate ion concentrations 10 times greater than those of human blood plasma. Photocatalytic activity of the apatite-deposited TiO2 powders was investigated in terms of the decomposition of methylene blue solution under ultraviolet (UV) irradiation. It has been shown that apatite deposition enhanced the photocatalytic activity of TiO2. The best photocatalytic performance was acquired on the powders that are immersed in SBF for 3 h. The time required for the complete degradation of methylene blue decreased from 3.5 h to 2 h upon immersion of powders in SBF for 3 h. Photochemical durability of poly(methyl methacrylate) increased when it was mixed with apatite-deposited TiO2 powders.
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Dogu, Doruk. "The Photocatalytic Activity Of Praseodymium Doped Titanium Dioxide." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12615056/index.pdf.
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In this study nanocrystalline TiO2 was synthesized by a sol-gel process. The effect of praseodymium (Pr) doping and calcination conditions on the textural properties of nano structured particles and photocatalytic activity were examined. Samples were synthesized by hydrolyzation of titanium tetra iso-propoxide (TTIP) and calcination at different temperatures. Characterizations of the samples were carried out using XRD, BET, XPS, TEM, and EDAX analyses. It was observed that anatase to rutile transformation is favored by higher calcination temperatures. The XRD analysis indicated that the anatase structure is stabilized by Pr doping and rutile phase formation at higher calcination temperatures is inhibited by the addition of Pr. It was also observed that Pr doping enhances the surface area and inhibit crystal growth. Phase stabilization effect of Pr doping was also confirmed by XPS results. EDAX analysis revealed that Pr is dispersed atomically in the crystal structure. The Photoluminescence analysis by 325 nm excitation indicated the emissions at 608 and 621 nm which can be attributed by photon up-conversion. The photocatalytic activities of the samples were measured by methylene blue degradation and phenol mineralization reactions. The photocatalytic activities of the Pr doped samples were also found higher than undoped TiO2 samples.
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Gan, Wee Yong Chemical Sciences & Engineering Faculty of Engineering UNSW. "Synthesis and characterization of titanium dioxide thin films." Publisher:University of New South Wales. Chemical Sciences & Engineering, 2009. http://handle.unsw.edu.au/1959.4/43310.
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In this thesis, titanium dioxide (TiO2)-based thin film photocatalysts of different morphologies were synthesized and studied for their photoelectrocatalytic and photocatalytic properties. The superhydrophilicity of selected TiO2 films were also assessed. The work started with the synthesis of nanocrystalline TiO2 thin films with minimal porosity. A photoelectrocatalytic study was performed to evaluate the films?? photocurrent response in the presence of various organic compounds. At low concentrations, the amount of photocurrent generated was found to be influenced by the molecular structure of the organic compounds. As the concentration increased, the photocurrent response became dependent on the level of interaction of the organic compounds and their partially degraded intermediates with the TiO2 surface. Highly dispersed platinum (Pt) were added onto TiO2 films by a photo-deposition method, and their photocatalytic and photoelectrocatalytic activities were assessed using a novel thin-layer photo(electrochemical)-catalytic system. The system allowed the photocurrent data that originated from the photoelectrocatalysis process to be collected in the reaction cell, and the amount of organic compound being oxidized to be quantified. The Pt deposits were found to enhance photocatalysis by increasing the photogenerated charge-carriers separation, but conversely they retarded the photoelectrocatalysis process. The next part of the work covered the development of mesoporous TiO2 films via the evaporative-induced self-assembly procedure. The structural characteristics of the films were altered by controlling the relative humidity and temperature during the coating and thermal treatment processes. The effect of key structural parameters, such as film porosity, surface area and crystallinity, on the photoelectrocatalytic activity was investigated. These parameters were found to affect the photoelectrocatalysis because the performance of a catalyst in the photoelectrocatalysis application relies strongly on attributes such as the photocatalyst particles?? interconnectivity and the contact to the conducting substrate. The last part of this thesis demonstrated the effort undertaken to improve the UV-induced superhydrophilic effect of a TiO2 film. A multilayer structure of TiO2 nanoparticles was assembled to create a novel TiO2 film that required no UV-activation to induce a uniform water sheeting across its surface. The novel TiO2 thin film exhibited stable superhydrophilic wetting and anti-fogging behaviors after repetitive cycles of heat and wetting treatment, and this performance was affected by the porosity and surface hydroxyl (-OH) contents.
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Dissanayake, Nishantha B. "Deposition of titanium dioxide by physical vapor deposition." Ohio : Ohio University, 2003. http://www.ohiolink.edu/etd/view.cgi?ohiou1175020765.
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Oymak, Mert Mehmet. "Photocatalytic Activity In Nano Sized Titanium Dioxide Structures." Phd thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615546/index.pdf.
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The objective of this thesis is to investigate the photocatalytic activity in nanosized TiO2 structures. Two different structures were used for two different reaction systems. In the first part of the study, TiO2 coated on glass beads by a sol-gel procedure were used to test the photocatalytic CO2 reduction reaction with H2O and H2 in the gas phase. The results of photocatalytic CO2 reduction reaction revealed that CO2 reduction step of the overall reaction proceeds in darkwhile illumination is required for water splitting reaction. In the second part of the study, Photocatalytic oxidation activity of the commercial TiO2 powders mixed with grout and plaster were studied for a potential commercial self cleaning material. A method based on gas phase benzene oxidation was developed for testing TiO2 added cement based self cleaning surfaces. This method was used to screen 15 commercial TiO2 samples with and without cement. Based on this method a commercial TiO2 sample (S9) was selected for further use. Surface of 15 commercial TiO2 samples were characterized by using NO and CO2 as probe molecules. Photocatalytic benzene oxidation experiments showed that using TiO2 on the surface lead to more effective surfaces in terms of photocatalytic activity. TiO2 was bound to surface by inorganic materials without much activity loss. This kind of amount optimization is of commercial importance.
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Buthelezi, Motlalepula Isaac. "Synthesis and properties of nanoparticulate titanium dioxide compounds." Thesis, University of the Western Cape, 2009. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_9038_1298632656.
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An electrolytic cell was designed and constructed for the preparation of TiO2 nanotubes. Conditions of anodic oxidation were established to reproducibly prepare TiO2 nanotubes of average length 35-50 &mu
m vertically orientated relative to the plain of a pure titanium metal sheet. A non-aqueous solution of ethylene glycol containing small percentage of ammonium fluoride was used as the electrolyte with an applied voltage of 60 V. The morphology and dimensions of the nanotube arrays were studied by scanning (SEM) and transmission (TEM) electron microscopy. The effect of calcination under different conditions of temperature and atmosphere (nitrogen, argon and air) were assessed by both X-ray diffraction (XRD) and cyclic voltammetry (CV). Cyclic voltammetry studies were made possible by construction of a specially designed titanium electrode upon which the nanotubes were prepared. CV studies established a positive correlation between crystallinity and conductivity of the nanotubes. Doping of the nanotubes with nitrogen and carbon was established by elemental analysis, X-ray photoelectron spectroscopy (XPS) and Rutherford back scattering (RBS). The effect of nonmetal doping on the band gap of the TiO2 nanotubes was investigated by diffuse reflectance spectroscopy (DRS).
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Kandasamy, Ispran S. "Metalorganic chemical vapour deposited titanium dioxide thin films." Thesis, Brunel University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235909.
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Duncan, Morris. "Surface and sensor studies of doped titanium dioxide." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365772.
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Mahalingam, Suntharavathanan. "Electrohydrodynamic processing and characterisation of titanium dioxide films." Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/1444321/.
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The research in this thesis demonstrates a novel electrohydrodynamic preparation of titanium dioxide (TiC>2) films. In this process, a liquid breaks up into spray droplets under influence of an electric field. This process is influenced by many factors properties of the liquid - surface tension, electrical conductivity, relative permittivity, viscosity, density and liquid flow rate and applied voltage. This technique has unique advantage like simple set-up and economical way to formulate the films. Many modes of processing were identified by drawing the mode-selection map for various applied voltage and flow rate using a titania sol. For a fixed flow rate, changing the applied voltage changed the processing mode. For a fixed applied voltage, changing the flow rate changed the shape of the liquid filament at the end of the needle. The stable cone-jet mode processing produced a near mono-disperse of droplets. The stable cone-jet processing of TiC>2 films showed anatase phase and converted to rutile phase at higher annealing temperature. The morphological characterisation revealed the dense and crack free surfaces of the TiC>2 films. The dielectric constant of the electrohydrodynamically processed TiC>2 films was 7. The increase in annealing temperature reduced the dielectric constant of the films. The leakage current density of the films was improved by post deposition annealing. The optical characterisation of the films showed a good transparency in the visible light region. The transmission in the visible range varied between 70-90%. The annealing temperature influenced the transmittance of the films. The energy bandgap is -3.50 eV for indirect transition. The larger coverage area nitrogen doped titanium dioxide films were obtained by using a metal clamped needle - ground electrode set-up for the first time. Metal clamping the needle lowered the stable cone-jet operating voltage window. The nitrogen doping in TiC>2 films retarded the phase formation however, showed anatase phase even at higher doping concentration. The absorption in doped films is higher than that of undoped ones by 8-15%.
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Gutierrez, Lucia Caballero. "Antibacterial properties of titanium dioxide in paint films." Thesis, Manchester Metropolitan University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506697.
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Qiu, Shipeng. "SYNTHESIS, PROCESSING AND CHARACTERIZATION OF NANOCRYSTALLINE TITANIUM DIOXIDE." Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3591.
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Titanium dioxide (TiO2), one of the basic ceramic materials, has found a variety of applications in industry and in our daily life. It has been shown that particle size reduction in this system, especially to nano regime, has the great potential to offer remarkable improvement in physical, mechanical, optical, biological and electrical properties. This thesis reports on the synthesis and characterization of the nanocrystalline TiO2 ceramic in details. The study selected a simple sol-gel synthesis process, which can be easily controlled and reproduced. Titanium tetraisopropoxide, isopropanol and deionized water were used as starting materials. By careful control of relative proportion of the precursor materials, the pH and peptization time, TiO2 nanopowder was obtained after calcination at 400oC. The powder was analyzed for its phases using X-ray powder diffraction (XRD) technique. Crystallite size, powder morphology and lattice fringes were determined using high-resolution transmission electron microscopy (HR-TEM). Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) were used to study the thermal properties. As-synthesized powder was uniaxially compacted and sintered at elevated temperature of 1100-1600oC to investigate the effects of sintering on nano powder particles, densification behavior, phase evolution and mechanical properties. Microstructure evolution as a function of sintering temperature was studied by scanning electron microscopy (SEM). The results showed that 400oC was an optimum calcination temperature for the as-synthesized TiO2 powder. It was high enough to achieve crystallization, and at the same time, helped minimize the thermal growth of the crystallites and maintain nanoscale features in the calcined powder. After calcination at 400oC (3 h), XRD results showed that the synthesized nano-TiO2 powder was mainly in single anatase phase. Crystallite size was first calculated through XRD, then confirmed by HR-TEM, and found to be around 5~10 nm. The lattice parameters of the nano-TiO2 powder corresponding to this calcination temperature were calculated as a=b=0.3853 nm, c=0.9581 nm, α=β=γ=90o through a Rietveld refinement technique, which were quite reasonable when comparing with the literature values. Considerable amount of rutile phase had already formed at 600oC, and the phase transformation from anatase to rutile fully completed at 800oC. The above rutilization process was clearly recorded from XRD data, and was in good corresponding to the DSC-TGA result, in which the broad exothermic peak continued until around 800oC. Results of the sintered TiO2 ceramics (1100oC-1600oC) showed that, the densification process continued with the increase in sintering temperature and the highest geometric bulk sintered density of 3.75 g/cm3 was achieved at 1600oC. The apparent porosity significantly decreased from 18.5% to 7.0% in this temperature range, the trend of which can be also clearly observed in SEM micrographs. The hardness of the TiO2 ceramics increased with the increase in sintering temperature and the maximum hardness of 471.8±30.3 HV was obtained at 1600oC. Compression strength increased until 1500oC and the maximum value of 364.1±10.7 MPa was achieved; after which a gradual decrease was observed. While sintering at ambient atmosphere in the temperature range of 1100oC-1600oC helped to improve the densification, the grain size also increased. As a result, though the sintered density at 1600oC was the highest, large and irregular-shaped grains formed at this temperature would lead to the decrease in the compression strength.M.S.M.S.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science and Engineering
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Green, Kevin J. "Photocatalytic studies with titanium dioxide and cadmium sulphide." Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335627.
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Mole, Jonathan Michael. "Titanium dioxide as a photocatalyst in water purification." Thesis, University of Kent, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309747.
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West, Richard Henry. "Modelling the chloride process for titanium dioxide synthesis." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611241.
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Fraser, Ian Muir. "Studies on the photocatalytic activity of titanium dioxide." Thesis, University of St Andrews, 1986. http://hdl.handle.net/10023/15530.
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A novel technique for determining the photoactivity of anatase and rutile forms of TiO2 has been developed. This involves measurement of the rate of oxygen-uptake in the propan-2-ol/propanone dehydrogenation system, which is photocatalysed by TiO2 particles maintained in suspension. The system has been studied under several experimental conditions, including the variation of incident light intensity and sample temperature. The effect of varying the alcohol concentration on the oxygen-uptake rate has been studied and, found to be related to the self-association properties of the alcohol, as determined from a series of NMR studies. In addition, strong organic bases have been shown to be effective in reducing the oxygen-uptake rate and a mechanism involving the blocking of surface sites on TiO2 is proposed. The generation and participation H2O2 of in the alcohol to ketone conversion has been studied and, in particular, a technique has been developed to enable the luminescence, which has been observed to emanate from the vortex of the irradiated suspension, to be studied under various experimental conditions. This technique revealed the rapid nature of the interaction of H2O2 at the TiO2 surface. The overall mechanism of the photocatalysed dehydrogenation is discussed in terms of two interdependent pathways: one involving oxygen, the other H2O2. Photoluminescence from dry, powdered samples of anatase and rutile has been observed at low temperatures upon excitation with a pulsed nitrogen laser. The decay kinetics of the photoluminesoence have been modelled via computer fitting techniques and the participation of two sets of trapping sites is postulated for anatase and rutile. The photophysical behaviour of benzophenone in poly(methylmethacrylate) films has been studied and a dual pathway for triplet deactivation, involving delayed fluorescence and triplet-triplet annihilation put forward.
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Sjogren, Jon Charles. "Inactivation of phage MS2 by titanium dioxide photocatalysis." Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187204.
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Viral disinfection by near-UV photocatalysis was accomplished in aqueous titanium dioxide suspensions. A photocatalyzed inactivation of phage MS2 of 90% increased to 99.9% after 2 μM Fe (from ferrous sulfate) was added to phosphate-buffered, distilled water containing TiO₂ and 20 μM Tris hydrochloride. Iron additions ranging from 0.2 to 20 μM, showed that a 2 μM Fe concentration produced maximum photoreactivity. The initial rate of MS2 inactivation, in the solution without iron, increased more than twenty-fold when Tris was absent. This rate of inactivation showed an additional nine-fold increase when the MS2 was photocatalyzed in a sample of Tucson groundwater, primarily because of low concentrations of groundwater species that scavenge hydroxyl radicals. A 99.997% inactivation of MS2 was observed after a 1000-ml glass beaker, containing a 100-ml suspension of MS2-spiked groundwater and 1 g l⁻¹ TiO₂, was exposed to sunlight for 10 sec. The hydroxyl radical (OH⋅) was linked to the MS2 destruction by verifying the ability of OH⋅ to inactivate MS2, and by demonstrating that OH⋅ was produced during the photocatalyzed reactions. An OH⋅ source, and competition kinetics techniques, were used to obtain these findings and to produce other evidence of MS2 inactivation by photocatalytically-produced OH⋅. These methods were also used to show that the presence of 2 μM Fe increased the quantity of liquid-phase OH⋅ that was produced during photocatalysis. Measurements showed that most of the added 2 μM Fe partitioned onto the TiO₂ surface, allowing the opportunity for OH⋅ production by Fenton reactions. Experimental results were consistent with proposed photocatalytic mechanisms (involving photocatalysis, diffusion, and Fenton reaction) by which OH⋅ was available on and off the TiO₂ surface. Non-OH⋅ means of MS2 inactivation were evaluated. The MS2 inactivation that occurred in unilluminated solutions to which Fe and TiO₂ were added, was probably caused by the effects of stirring, oxidation by iron, and MS2 enmeshment in aggregating TiO₂ particles.
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Amsaaed, Salem. "Copper Grafted Titanium Dioxide in Hydrogels for Photocatalysts." DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 2018. http://digitalcommons.auctr.edu/cauetds/155.
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This study are based on the premise that the incorporation of metal ions into nano titania-PHEMA [poly (2-hydroxyethyl methacrylate)] hydrogels would enhance the desirable properties in the photodecomposition of pollutants. The investigation are centered in the use of Cu(II) as metal ion of interest. The development of TiO2-PHEMA-Cu hydrogels was conducted, and the characterization of the materials by FT-IR, XRD and fluorescence was performed. The absorption of copper(II) from the solution was monitored by UV-Vis. The FT-IR are found too, be the most effective tool too, analyze the interaction of Cu(II) with PHEMA in the nanocomposite hydrogels. The free carbonyl group has the IR band at 1715 cm-1 in the TiO2-PHEMA. Upon uptaking Cu(II), the hydrogels showed a new band at 1595 cm-1. Further examination establishes the relationship between the two bands. The time-dependent study revealed that the intensity of band at 1595 cm-1 would increase while that at 1715 cm-1 would decrease as the time for uptaking Cu(II) increased. A concentration-dependent study also demonstrated the same trend that showed the intensities of the two bands moved in the opposite directions.
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SINGH, MRITYUNJAY. "IVESTIGATIONS OF METAL ASSISTED TITANIUM DIOXIDE (TiO2) NANOCRYSTALS." Thesis, DELHI TECHNOLOGICAL UNIVERSITY, 2021. http://dspace.dtu.ac.in:8080/jspui/handle/repository/18623.
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7.1 Summary
The research topic of the thesis entitled “Investigations of Metal Assisted Titanium Dioxide (TiO2) Nanocrystals” disclosed the structural, morphological, compositional and optical properties of TiO2 nanoparticles (NPs) and discussed their utility for photocatalytic applications.
In the current thesis, TiO2 NPs were prepared using the sol-gel method and comprehensively explored their properties. The crystalline structural and optical characteristics of TiO2 NPs (like X-ray diffraction, absorption, photoluminescence, and time-resolved photoluminescence) along with photocatalytic applications have also been discussed in detail in the previous chapter.
7.2 Important Findings of Research Work
Nanocrystals of anatase, mixed and rutile phases of TiO2 and metal-doped TiO2 have been synthesized via the sol-gel method. The prepared samples were characterized by various analytical tools. For the structural and surface morphology analysis, essential tools such as XRD, SEM and TEM were used. EDX analysis has been carried out for elemental identification present in prepared nanomaterials. TGA, FTIR spectroscopy, Raman spectroscopy, UV-visible & PL spectroscopy, time-resolved photoluminescence (TRPL) spectroscopy at varying temperatures were used to understand the structural and transitions following photoexcitation.
TiO2 NPs were prepared by the sol-gel method with titanium isopropoxide as a precursor at different annealing temperatures. The analyzed XRD patterns, Raman and Fourier transform infrared spectra demonstrated the structural transformation from
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amorphous to anatase and further to rutile phase while increasing annealing temperature. In addition, a mixed-phase of TiO2 NPs is formed, which consists of both phases. The absorption and photoluminescence (PL) spectra of mixed and rutile phases are shifted towards a longer wavelength region. The indirect band gap structure changed into the direct band gap during the structural transformation. Both absorption and PL spectra shifted towards lower energy regions, which might be due to the increase in size or the induced oxygen vacancies produced at a higher temperature.
Furthermore, the photocatalytic activity of all the three different structural TiO2 NPs was examined. Furthermore, the photocatalytic performance of the different types of TiO2 NPs was examined through the degradation of a dye, rhodamine B (RhB), under UV radiation and measuring changes in absorption and PL spectra. The anatase phase structure shows higher photocatalytic activity than the rutile phase. However, the mix phase has the highest photocatalytic activity among all the structures, which degraded RhB entirely at a faster rate. On the other hand, the rutile phase is unable to take part in this process. Thus, the mix phase of TiO2 NPs is beneficial for industrial and environmental applications.
The transition metal ions (Ag+, Cu2+, and Ni2+) doped and undoped TiO2 NPs have been synthesized using a cost-effective sol-gel method with a 1.0 wt% dopant concentration. The microstructure and chemical compositions of these NPs were examined using various techniques such as x-ray diffractometric, field emission scanning electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared and absorption and photoluminescence (PL) spectroscopy. The absorption and photoluminescence (PL)-excitation spectra of metal-doped TiO2 NPs are shifted to the longer wavelength region, which indicates a reduced bandgap than the bare TiO2 NPs. The absorption and PL spectra of methylene blue (MB) in the presence of undoped and metal ions doped TiO2 NPs show dramatic changes upon UV-irradiation. The absolute absorption
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intensity reduced entirely and the solution of MB became colorless in the presence of UV irradiation. The PL of the degraded dye exhibits a new band in the shorter wavelength region, which has a multi-exponential decay function and an increased average PL lifetime. The dye degradation rate is higher for metal ions doped catalyst and highest for Cu2+ doped TiO2 NPs. Thus, Cu ions-doped TiO2 shows the highest photocatalytic activity. The order of catalytic degradation rate under UV irradiation was found to be Cu– TiO2 > Ni– TiO2 >Ag– TiO2 >anatase TiO2. The analysis of the PL spectra and PL-decays reveals the formation of smaller species that emits at a shorter wavelength region, thus helps in understanding the degradation of dye molecules.
TiO2 NPs synthesized by employing the sol-gel routes and annealed at a different temperature from 400 to 900 °C. Three different nanostructures were formed, namely anatase, mixed (anatase/rutile) and rutile phases. The structure and morphology of as-synthesized NPs were confirmed using XRD and FESEM analysis. The XRD analysis of TiO2 NPs was carried out in the 290 K to 77 K temperature range and found no significant change in XRD patterns that means thermally stable TiO2 NPs. The PL spectra and contour maps of TiO2 NPs show that the anatase phase falls in the visible region. However, mixed and rutile phases fall in both visible and NIR regions as the temperature decreases from 290 K to 77 K. The visible PL band is ascribed to donor-acceptor recombination. In contrast, oxygen vacancies serve as donors and hydroxyl groups function as accepter sites. NIR PL band attributed to the trapped electrons in rutile TiO2, which recombine with free holes and intrinsic defects. The fast component of the decay processes was aided by the immediate formation of trapped electrons in luminescence sites. The indirect trap processes were responsible for the power-law component in the rutile phase, which was the recombination of trapped electrons formed via a deep trap state. It was observed that the electron-hole pairs thermally separated, preventing the formation of STEs directly. The PL
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and PL decay studies under weak excitation conditions prove to be a more valuable and appropriate method to evaluate the trap states distribution and their carrier dynamic effects, which were vibrant to understand the photocatalytic processes better.
Two-dimensional (2D) layered MoS2 nanosheets (NSs), which possess a vast range of unique properties and hold great potential for various applications. MoS2 NSs were synthesized by a hydrothermal method and the obtained NSs bear crystalline and layered structure. Absorption and electroabsorption (E-A) spectra of MoS2 doped in a PMMA thin film were measured at different temperatures (290-40 K). The E-A spectra observed at the second harmonic of the modulation frequency of the applied electric field (1.0 kHz) were analyzed with an integral method by assuming the Stark effect as a dominant feature. The absorption spectra consist of multiple transitions, among which five transitions are contributed to the E-A spectra. The changes in electric dipole moment (Δμ) and polarizability (Δα) of each transition were determined at different temperatures. Two electronic resonance states were identified for two excitonic bands of MoS2 NSs, which showed a strong E-A signal.
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Liu, Dong. "Effects of metal modification on titanium dioxide for photocatalytic reduction of carbon dioxide." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/28624/.
Full textAbstract:
To study the effects of metal modification on titanium dioxide (TiO2) for photocatalytic reduction of carbon dioxide (CO2), a series of pure and metal modified TiO2 catalysts (referred as SG TiO2 and M/TiO2, respectively) were synthesized via a refined sol-gel process. The metals chosen to modify TiO2 included Cu, Zn, and Rh. These catalysts were then characterized by using various analytical techniques, including ICP-MS, powder XRD, XPS, TEM, N2 adsorption isotherms, Cu surface area and dispersion measurement, and DR UV-Vis. It was found that all the sol-gel derived TiO2 catalysts had the same crystalline phase of anatase, and similar particle sizes (11-16 nm) and surface areas (50.24-63.37 m2/g). It is worthy to note that, even though synthesized via the same sol-gel process, the three added metals modified their TiO2 supports differently. The added Cu and Zn were loaded on the surface ofTiO2 with their chemical states to be CU2O and ZnO, respectively. Whereas, the added Rh was substitutionally doped into the lattice of its TiO2 supports. The specific surface area and dispersion of the added Cu on the surface of CulTiO2 were further measured by using N2O as adsorbate. It was found that the aggregation of the added Cu occurred when the Cu ratio of Cu/TiO2 over-increased (over 0.03 wt%). The following CO2 photoreduction experiments confirmed that the added Cu and Rh were able to significantly improve the activity of TiO2 for CO2 photoreduction to methane, wherein the activities of the best performing 0.03 wt% Cu/TiO2 and 0.01 wt% Rh/TiO2 were around 10-times higher than that of SG/TiO2. The added Cu and Rh were expected to affect the activity of TiO2 via different ways. The combination of the loaded Cu and TiO2 was considered to be a composite semiconductor catalyst, and the Cu dispersion dominated the activity of Cu/TiO2. In comparison, the doped Rh was able to affect the activity of TiO2 by introducing an additional energy level to the band-gap of TiO2. Finally, TiO2 catalysts simultaneously loaded by Cu and doped by Rh (Rh/Cu/TiO2, synthesized via the identical sol-gel process) were also tested for CO2 photoreduction. The results indicate that the loaded Cu and doped Rh were able to synergistically enhance the activity of TiO2 for CO2 photoreduction, allowing the optimal Rh/Cu/TiO2 (0.06 wt% Rh/O.03 wt% Cu/TiO2) to present even better (at least 25 % higher) activity than any of the Cu/TiO2 or Rh/TiO2 in this work.
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Song, Inho. "Defect structure and DC electrical conductivity of titanium dioxide-niobium dioxide solid solution." Case Western Reserve University School of Graduate Studies / OhioLINK, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=case1054571769.
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Wen, William Y. "Development of New Characterisation Methods to Study the Photocatalysis Processes at Nanoparticulate TiO2 Film Electrodes." Thesis, Griffith University, 2011. http://hdl.handle.net/10072/366132.
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Titanium dioxide, TiO2, has a wide range of applications as a photocatalyst in the field of solar energy conversion and environmental remediation including water purification and wastewater treatment. In general, a TiO2 photocatalytic process consists of three major steps, namely, the mass transfer process in solution, the interfacial step, and the photoelectron transport inside the catalyst. This work explores the characterisation of TiO2 photocatalysis using a photoelectrochemical method to focus on each fundamental reaction steps. Each of these steps will be used to gain an accurate understanding of processes and identify possible improvements of the overall performance of TiO2 semiconductor photocatalysts. In this work, nano-sized TiO2 semiconductor photocatalysts were prepared by the solgel method, and immobilised onto a conducting ITO glass substrate to form a photoanode. Photocatalytic studies utilising immobilised TiO2 thin films have many advantages over the suspension/slurry system, including the elimination of the separation process. Most importantly however, photocatalysis by immobilised TiO2 photocatalyst can be manipulated by applying an external potential bias to focus on understanding certain aspects of the photocatalytic process (e.g. the rate determining steps).Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Nagpal, Vidhu JaiKishen. "In-situ steric stablization of ultrafine titania particles synthesized by a sol-gel process /." This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-07282008-135003/.
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Wang, Yushan. "First-principles investigations of electronic structures of pristine and doped anatase titanium dioxide." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 182 p, 2007. http://proquest.umi.com/pqdweb?did=1354136771&sid=25&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Ahonen, P. P. "Aerosol production and crystallization of titanium dioxide from metal alkoxide droplets /." Espoo [Finland] : Technical Research Centre of Finland, 2001. http://www.vtt.fi/inf/pdf/publications/2001/P439.pdf.
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Kumar, Sachin. "Gas Phase Oxidation of Dimethyl Sulfide by Titanium Dioxide Based Catalysts." Miami University / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=miami1081780904.
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Chen, Lung-Chyuan, and 陳龍泉. "Photodegradation of Methyl Orange Using Titanium Dioxide and Modified Titanium Dioxide as Photocatalysts." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/62738031944004472601.
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博士國立成功大學
化學工程研究所
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Solar energy containing 10% of ultraviolet is a clean and cheap energy source and can be used to generate electrons and holes at semiconductors or photocatalysts by irradiation. The waste water containing azo compounds is a serious problem since the azo dyes are the most widely used in textile industry. Accordingly, the photodecolorization of azo compounds by photo- catalytic reaaction is an interesting and potential topic. Ph- otodecolorization of methyl orange using titanium dioxide and silver ion modified titanium dioxide as photocatalysts were both experimental and theoretical studied in this dissertation since methyl orange is a typical azo compound. Electrodecolor- ization of methyl orange using graphite as both cathode and anode was also carried out. The light source wsa 1000W mercury lamps. The photoreactors were made of PYREX glass and quartz. The experimental results showed that no methyl orange was decomposed by photochemistry reaction and the adsorption of methyl orange on titanium dioxide was trace and could be negle- cted. Decolorization of methyl orange proceeded through oxidat- ion reaction promoted by the hydroxyl radical that was generated from the reaction of holes and hygroxyl groups or water adsorbed on the surface of titanium dioxide in the alkaline solution. However, the reaction proceeded through both oxidation and photo reduction procedures. Tungsten oxide, barium titanate, ferric oxide and molybdenum(vi) oxide showed little catalytic activity on the photodecolorization of methyl orange. Zinc oxide and ti- tanium dioxide have much more activity on this reaction system, but the resistance to photocorrosion of zinc oxide is poor. Ti- tanium dioxide was more suitable to this reaction system owing to the high activity and better anti-photocorrosion.(omit)
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Lee, Tang-Ming, and 李唐明. "Effect of the Titanium Dioxide Content on the Interfacial Reactions between Titanium and Zirconia/ Titanium Dioxide Composites." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/54592279577258969501.
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Ching, Chih-Wen, and 鄭智文. "CVD titanium dioxide and the doping effect of zirconium dioxide and MPECVD titanium carbide." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/85670155368279667598.
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Tsai, Chung Lun, and 蔡宗倫. "Fabrication and properties of titanium dioxide based humidity sensorFabrication and properties of titanium dioxide based humidity sensorFabrication and properties of titanium dioxide based humidity sensor." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/77449212040083603282.
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碩士國立高雄海洋科技大學
微電子工程研究所
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In environmental control, humidity detection is very important. In particular, precise humidity detection is necessary in the industry of high technology and manufacturing industries. Therefore, the sensors changed the structure to improve the sensing effect. In this study, the humidity sensors were produced by using the RF sputtering. TiO2 films as sensing membranes of the humidity sensor. Interdigital electrode was produced by thermal evaporation system. This thesis fabricates two kinds of sensor structure devices including Al/TiO2/Si (MOS), TiO2/Al/TiO2/Si (OMOS). The response time for these sensor are 120s and 50s respectively. The TiO2 thin film were prepared at growth temperature of 400℃, it shows improvement to the hysteresis and response time of sensors. The recovery time required about 30 seconds in the range of 90%-30% RH at 27℃.