Un nanotube de dioxyde de titane autoporteur (TiO2 nts) est exploré en tant qu’électrode négative potentielle pour les microbatteries Li-ion 3D. Différentes modifications chimiques du TiO2 ont été explorées et étudiées, comme le TiO2 allié au Nb, le TiO2 revêtu d'ALD-Al2O3, le titanate de lithium-TiO2 et le TiO2 sulfuré. Le dépôt d'électrolyte polymère à base de PEO (oxyde d'éthylène) (PMMA-PEG) portant le sel de LiTFSI dans du TiO2 a été obtenu par la réaction d'électropolymérisation sur l'anode TiO2 et la cathode Lithum nickel oxyde de manganèse (LNMO). L'objectif principal ici était d'exploiter la surface active des électrodes par électrodéposition et d'améliorer ainsi l'interface électrode-électrolyte. Une telle micro-batterie contenant des électrodes revêtues de polymère révèle que les valeurs de capacité obtenues à différents taux de C sont doublées lorsque les électrodes sont complètement remplies par l'électrolyte polymère par rapport à la micro-batterie à électrodes brutes. Les excellentes performances électrochimiques sont attribuées aux interfaces électrode-électrolyte améliorées dans les deux électrodes / Self-supported titanium dioxide nanotube (TiO2 nts) is explored as a potential negative electrode for 3D Li-ion microbatteries. Different chemical modifications on the TiO2 nts have been explored and studied like Nb-alloyed TiO2 nts, ALD-Al2O3 coated TiO2 nts, Lithium titanate-TiO2 nts and sulphurized TiO2 nts. The deposition of PEO (polyethylene oxide) based polymer electrolyte (PMMA-PEG) carrying LiTFSI salt into TiO2 nts has been achieved by the electropolymerization reaction on the TiO2 nts anode and the Lithum nickel manganese oxide (LNMO) cathode. The main aim here was to exploit the active surface area of the electrodes using electrodeposition and there by enhance the electrode-electrolyte interface. Such a microbattery containing polymer-coated electrodes reveal that the capacity values obtained at different C-rates are doubled when the electrodes are completely filled by the polymer electrolyte compared with the microbattery with the raw electrodes. The excellent electrochemical performance is attributed to the improved electrode-electrolyte interfaces in both the electrodes

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This research studies the use of class=SpellE>titania (titanium dioxide, TiO2) as a catalyst for deoxygenation of class=SpellE>syngas derived oxygenates. These oxygenates are formed as byproducts when biomass derived syngas (CO & H2) is converted to ethanol on Rhodium or Molybdenum based catalysts. Conversion of these oxygenates to hydrocarbon would enhance the viability of class=SpellE>syngas to gasoline technology. This study revealed that class=SpellE>titania can indeed be used to convert syngas derived oxygenates to hydrocarbon at high temperature and pressure. Acetone condensation to mesitylene was studied very closely. The study revealed that the acid-base dual nature of class=SpellE>titania is key for the success of this reaction. When titaniawas combined with the zeolite H+/ZSM-5, a broad range of gasoline type hydrocarbon could be produced. Ethanol conversion to higher alcohols was studied as part of a partial deoxygenation of ethanol research. While this conversion was possible on class=GramE>titania, zirconia proved to be a better catalyst. Ethanol could be converted to 1-butanol and other higher alcohols at high temperature and pressure. The mechanism by which this occurs was studied as well.

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Titania (Titanium dioxide, TiO2) has been researched as a promising biomaterial due to its excellent biocompatibility. However, the main limitation of titania is its poor mechanical properties which limit its use in many load-bearing applications. In this thesis report, the properties of titania were improved by doping with small quantities of MgO, ZnO and SiO2 as sintering additives. Nanocrystalline powder was selected, as it possesses outstanding properties over conventional coarse-grained powders due to reduced grain size. Nanocrystalline anatase powder of size 5-15 nm was synthesized via a simple sol-gel technique. Small quantities of dopants were introduced into pure titania powder, through homogeneous mixing. The doped powder compositions were compacted uniaxially and sintered at 1300°C and 1500°C, separately, in air. The effects of sintering cycle and temperature on the microstructure, densification and mechanical properties of the sintered structures were studied. Mg doped structures recorded maximum sintered density of 3.87 g.cm-3. Phase analysis was carried out using powder XRD technique using Cu K[alpha] radiation. Microstructural analysis was performed using Scanning electron microscopy. The mechanical properties were assessed by evaluating hardness and biaxial flexural strength (ASTM F-394) of the structures. Results showed 12% increase in hardness and 18% increase in biaxial flexural strength in structures doped with ZnO and SiO2, respectively. Further, simulated body fluid maintained at 36.5°C was used to study the bioactivity and degradation behavior of the structures. The second part of the work aimed in the processing of porous titania scaffolds using polyethylene glycol as the pore-former. The green structures were sintered at 1400°C and 1500°C, separately in air and their properties have been studied. Microstructural analysis was carried out using Scanning electron microscope (SEM). Porosity was evaluated using the immersion technique. Vickers hardness and biaxial flexural tests were used to carry out the mechanical characterization. Further, the biomechanical/biodegradation behavior of the structures was assessed in simulated body fluid (SBF). Biodegradation and change in biomechanical properties as a function of time were studied in terms of weight change, change in Vickers hardness and biaxial flexural strength. The mechanical properties of porous titania scaffolds doped separately with MgO and ZnO have also been studied to investigate the influence of these additives on the properties of porous structures. The Vickers hardness and biaxial flexural strength were seen to improve with the addition of these sintering additives.

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