Global ETD Search

1	Molecular Modeling Study of Oxidative Degradation of Polyperfluoroethers Catalyzed by Iron Fluoride Surfaces : An Extended Hückel Theory Approach Wang, Yanbin 05 1900 (has links) Extended Hückel methods are known to be a useful tool in understanding surface phenomena. Important quantities about atoms and chemical bonds can be obtained from this computationally simple method, although caution must be exercised in interpreting the results. Application of Extended Hückel calculations to large metal clusters reveals the role of d orbitals in solids. Basic ideas of constructing model compounds have been developed. Several model systems for surface chemisorption processes are constructed in order to understand the surface catalyzed oxidative degradation of polyperfluoroethers. The activation of oxygen molecules can be explained. The Lewis acid character of the iron fluoride surface can be predicted. Based on these results, mechanisms of the degradation processes are discussed. molecular modeling oxidative degradation polyperfluoroethers iron fluoride surfaces Hückel theory Hückel molecular orbitals.
2	Iron Fluoride-Based Positive Electrode Materials for Secondary Batteries Using Ionic Liquid Electrolytes / イオン液体電解質を用いた二次電池用フッ化鉄系正極材料 Zheng, Yayun 23 March 2022 (has links) 京都大学 / 新制・課程博士 / 博士(エネルギー科学) / 甲第24003号 / エネ博第439号 / 新制\|\|エネ\|\|83(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻 / (主査)教授萩原理加, 教授佐川尚, 教授野平俊之 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM Secondary batteries Iron fluoride-based positive electrodes Ionic liquid electrolytes Elevated temperatures Phase evolution 501
3	Accumulateur lithium-ion à cathode de fluorures de métaux de transition / Transition metal fluoride for lithium-ion batteries applications Delbegue, Diane 25 September 2017 (has links) Les batteries lithium ions sont la technologie de référence pour le stockage électrochimique de l’énergie. Cependant, les matériaux cathodiques de ces batteries comme LiCoO2, LiMn2O4 ou LiFePO4 présentent une capacité spécifique limitée (<160 mAh/g). De nombreux composés sont à l’étude pour améliorer cette performance dont le fluorure de fer (III) en raison de sa capacité théorique de 711 mAh.g-1. Ce travail présentera la synthèse de FeF3 par différentes méthodes de fluoration. Les matériaux obtenus seront comparés en termes de structures et de liaison (DRX, Mössbauer, spectroscopies IR et Raman) mais aussi de texture (isothermes d’adsorption à l’azote à 77K). Les propriétés électrochimiques des matériaux obtenus seront également comparées et testées. Enfin, l’étude du mécanisme électrochimique de cette famille de composés sera menée via une méthode de caractérisation « in operando » : la spectroscopie d’absorption des rayons X (XAS). / The lithium-ion batteries are the current solution for electrochemical energy storage. However, their performances are limited by the cathode materials, such as LiCoO2, LiMn2O4 or LiFePO4 of specific capacity lower than 160 mAh/g. Many materials are good candidates to improve this capacity such as iron trifluoride of theoretical capacity of 711 mAh.g-1. This work will present the synthesis of FeF3 through different fluorination ways. The resulting materials will be characterized owing to their structure by XRD, Mössbauer, Raman and IR spectroscopies and their texture by nitrogen adsorption isotherms at 77K and SEM. After that, the electrochemical properties will be evaluated and compared. Finally, the study of the electrochemical mechanism of this family of compounds will be led with a method of characterization “in operando” : the X-rays absorption spectroscopy (XAS). Fluoration Fluorure de fer Batterie lithium-ion Cathode Mossbauer DRX XAS Fluorination Iron fluoride Lithium-ion battery Cathode material XAS XRD Mossbauer
4	Novel nanoscopic FeF 3 –based materials Guo, Ying 25 July 2013 (has links) Das Hauptaugenmerk dieser Arbeit liegt auf einer Pilotstudie zur Darstellung von Eisen(III)fluorid (FeF3) unter Verwendung von Sol-Gel-Syntheserouten. Eine modifizierte fluorolytische Sol-Gel-Synthese wurde entwickelt um bi-acide auf FeF3 basierende Materialien zu erhalten. Die Synthese erzeugt Hydroxygruppen, die potentiellen Brønsted-sauren Zentren, auf der Oberfläche der klassischen Lewissäure FeF3. Im Anschluss wurde Magnesiumfluorid (MgF2) als Matrix eingesetzt. Verglichen mit FeF3 zeigen ternäre FeF3-MgF2 bemerkenswert hohe Oberflächen und verbesserte Porosität. Das Wichtigste jedoch ist, das hauptsächlich starke Lewis- und mittelstarke Brønsted-saure Zentren auf der FeF3-MgF2 vorhanden sind. Des Weiteren wurden, unter Verwendung anderer Erdalkalimetallfluoride (CaF2 oder SrF2) und Zinkfluorid (ZnF2) als Matrix, Serien ternärer Fluoridmaterialien synthetisiert und systematisch untersucht. Durch Charakterisierung der FeF3-MF2-Oberflächen konnten systematische Veränderungen hinsichtlich Größe der Oberfläche, Porosität und Azidität festgestellt werden. Mit abnehmender Atomnummer (von Sr zu Mg) erhöht sich die Stärke der sauren Zentren, während die mittlere Porengröße dramatisch abnimmt. Darüber hinaus führt ein größeres M-zu-Fe-Verhältnis generell zu kleineren Porengrößen und höheren Oberflächen. Diese Ergebnisse implizieren, dass die Eigenschaften ternärer FeF3-MF2 durch Veränderung der MF2-Matrix oder des M-zu-Fe-Verhältnisses einstellbar sind. Schlussendlich konnte anhand einer Modellreaktion, der Isomerisierung von Citronellal zu Isopulegolen, die katalytische Aktivität der bi-aziden Zentren der auf FeF3 basierenden Materialien nachgewiesen werden. Zusätzlich wurde in dieser Arbeit diskutiert wie Oberfläche, Porosität und Azidität gemeinsam die katalytische Aktivität von FeF3-MgF2 bestimmen. Diese Arbeit beweist damit die Realisierbarkeit der Synthese neuer nanoskopischer Metallfluoride mit gewünschten Oberflächeneigenschaften. / This work serves as a pilot study on the development of iron(III) fluoride (FeF3) based materials with surface bi-acidity. A modified fluorolytic sol-gel route was established to prepare the bi-acidic FeF3-based materials. The synthesis procedure introduced hydroxyls, the potential Brønsted acid sites, on the surface of a classic Lewis acid, FeF3. Subsequently, magnesium fluoride (MgF2) was used as matrix. Comparing with FeF3, the ternary FeF3-MgF2 showed remarkable high surface area and enhanced porosity. Most importantly, strong Lewis and medium strong Brønsted acid sites were found predominant on the FeF3-MgF2 surface. Next a series of ternary fluoride materials were synthesised and studied systematically, using other alkaline earth metal fluorides (CaF2 or SrF2) as well as zinc fluoride (ZnF2) as matrices. Surface characterisation of FeF3-MF2 revealed systematic changes in their surface area, porosity, and surface acidity. With decreasing atom numbers (from Sr to Mg), strengths of surface acidic sites and surface area increased, while the average pore size decreased drastically. Moreover, higher M-to-Fe ratio generally resulted in smaller pore size and larger surface area. These findings imply that the properties of ternary FeF3-MF2 are tunable by changing the MF2 matrix or the M-to-Fe ratio or both. Last but not least, in the model reaction, isomerisation of citronellal to isopulegols, FeF3-based materials were highly active due to their bi-acidity. Finally this work discussed how surface area, porosity, and surface acidity jointly determined the catalytic activity of FeF3-MF2. In conclusion, this work demonstrates the feasibility to synthesise novel nanoscopic metal fluorides with desirable surface properties. heterogene Katalyse Bi-Azidität Eisenfluorid Nanomaterial Sol-Gel-Synthese heterogeneous catalysis bi-acidity iron fluoride nanomaterial sol-gel process 540 Chemie 30 Chemie VE 7047 VH 8010 VH 9707 ddc:540
5	Electron Transfer and Other Reactions Using Atomic Metal Anions Butson, Jeffery M. 04 February 2014 (has links) The atomic metal anions Rb-, Cs-, Cu-, Ag- and Fe- have been generated in the gas phase and reacted with various neutral reactants in a triple quadrupole mass spectrometer. The metal anions were formed via electrospray ionization of the metal-oxalate solutions and form in gas phase between the capillary and the first quadrupole. Neutral gas phase reactants investigated include NO, NO2, SO2, C6F5OH, C6F5NH2, C6F6, E-octafluoro-butene and 1,2,3/1,2,4/1,3,5 trifluoro-benzene. When possible, CBS-4M methods were used to suggest the lowest energy products based on relative energy. Observed reactions of atomic metal anions with the aforementioned neutral species include electron transfer and dissociative electron transfer to the neutral gas phase reactants. In addition, hydrogen abstraction and fluorine abstraction forming a neutral metal hydride or fluoride as well as the formation of multiply substituted metal-oxide/fluoride anions was also observed. Metal-complex anions observed from the gas phase reactions include CuF-,CuF2-,CuO-,CuO2-, FeO-, FeO2-, FeO3-, FeF-, FeF2-, FeF3-, CsF- and CsF2-. Metal Anion Metal Anion Atomic Atomic Metal Anion Atomic Metals Atomic Metal Anions Anions Metals Mass Spectrometer Triple Quadrupole Rb Cs Fe Cu Ag Cs- Rb- Fe- Cu- Ag- pentafluoroaniline pentafluorophenol nitrogen dioxide sulfur dioxide nitrogen oxide nitrogen monoxide oxygen oxalic oxalic acid gas phase electrospray ionization electrospray ionization electro-spray ionization electro-spray hexafluorobenzene 1,2,3-trifluorobenzene 1,2,4-trifluorobenzene 1,3,5-trifluorobenzene fluorine E-octafluoro-butene octafluoro-butene octafluoro butene CBS-4M abstraction hydrogen abstraction fluorine abstraction hydride fluoride metal hydride metal fluoride caesium fluoride rubidium fluoride iron fluride copper fluoride rubidium caesium iron copper silver iron anion copper anion rubidium anion caesium anion silver anion cesium cesium anion atomic caesium anion atomic cesium anion atomic rubidium anion atomic iron anion atomic copper anion atomic silver anion 1,2,3 trifluorobenzene 1,2,4 trifluorobenzene 1,3,5 trifluorobenzene copper fluoride anion iron fluoride anion copper difluoride copper difluoride anion iron difluoride iron difluoride anion iron trifluoride iron trifluoride anion cesium fluoride cesium fluoride anion caesium difluoride anion caesium difluoride cesium difluoride cesium difluoride anion caesium fluoride anion nitrogen monoxide anion sulfur dioxide anion nitrogen dioxide anion copper oxide copper oxide anion copper dioxide copper dioxide anion iron oxide iron oxide anion iron dioxide iron dioxide anion iron trioxide iron trioxide anion electron transfer
6	Electron Transfer and Other Reactions Using Atomic Metal Anions Butson, Jeffery M. January 2014 (has links) The atomic metal anions Rb-, Cs-, Cu-, Ag- and Fe- have been generated in the gas phase and reacted with various neutral reactants in a triple quadrupole mass spectrometer. The metal anions were formed via electrospray ionization of the metal-oxalate solutions and form in gas phase between the capillary and the first quadrupole. Neutral gas phase reactants investigated include NO, NO2, SO2, C6F5OH, C6F5NH2, C6F6, E-octafluoro-butene and 1,2,3/1,2,4/1,3,5 trifluoro-benzene. When possible, CBS-4M methods were used to suggest the lowest energy products based on relative energy. Observed reactions of atomic metal anions with the aforementioned neutral species include electron transfer and dissociative electron transfer to the neutral gas phase reactants. In addition, hydrogen abstraction and fluorine abstraction forming a neutral metal hydride or fluoride as well as the formation of multiply substituted metal-oxide/fluoride anions was also observed. Metal-complex anions observed from the gas phase reactions include CuF-,CuF2-,CuO-,CuO2-, FeO-, FeO2-, FeO3-, FeF-, FeF2-, FeF3-, CsF- and CsF2-. Metal Anion Metal Anion Atomic Atomic Metal Anion Atomic Metals Atomic Metal Anions Anions Metals Mass Spectrometer Triple Quadrupole Rb Cs Fe Cu Ag Cs- Rb- Fe- Cu- Ag- pentafluoroaniline pentafluorophenol nitrogen dioxide sulfur dioxide nitrogen oxide nitrogen monoxide oxygen oxalic oxalic acid gas phase electrospray ionization electrospray ionization electro-spray ionization electro-spray hexafluorobenzene 1,2,3-trifluorobenzene 1,2,4-trifluorobenzene 1,3,5-trifluorobenzene fluorine E-octafluoro-butene octafluoro-butene octafluoro butene CBS-4M abstraction hydrogen abstraction fluorine abstraction hydride fluoride metal hydride metal fluoride caesium fluoride rubidium fluoride iron fluride copper fluoride rubidium caesium iron copper silver iron anion copper anion rubidium anion caesium anion silver anion cesium cesium anion atomic caesium anion atomic cesium anion atomic rubidium anion atomic iron anion atomic copper anion atomic silver anion 1,2,3 trifluorobenzene 1,2,4 trifluorobenzene 1,3,5 trifluorobenzene copper fluoride anion iron fluoride anion copper difluoride copper difluoride anion iron difluoride iron difluoride anion iron trifluoride iron trifluoride anion cesium fluoride cesium fluoride anion caesium difluoride anion caesium difluoride cesium difluoride cesium difluoride anion caesium fluoride anion nitrogen monoxide anion sulfur dioxide anion nitrogen dioxide anion copper oxide copper oxide anion copper dioxide copper dioxide anion iron oxide iron oxide anion iron dioxide iron dioxide anion iron trioxide iron trioxide anion electron transfer

1

Page generated in 0.0725 seconds