Cette thèse a été consacrée à l’étude en laboratoire plusieurs molécules d’intérêt astrophysique par spectroscopie par transformation de Fourier dans l’infrarouge lointain afin de montrer les possibilités offertes par cette gamme spectrale en matière de spectroscopie vibrationnelle et rotationnelle, notamment grâce à l’utilisation du rayonnement synchrotron. Nous nous sommes intéressés à des molécules relativement lourdes, dérivées du naphtalène, pour lesquelles nous avons pu observer les bandes de vibrations de plus basses fréquences. Nous avons également développé différents dispositifs de décharge permettant d’étudier la spectroscopie rotationnelle de molécules instables : molécules légères à haute température et radicaux de petite taille. / This thesis has been dedicated to the laboratory far-infrared Fourier transform spectroscopy of several molecules of astrophysical interest in order to demonstrate the interest of this spectral region for vibrational and rotational spectroscopy, in particular using synchrotron radiation. Low frequency vibrational spectra of nine naphthalene derivatives, relatively heavy molecules, have been studied. Several discharge set-ups have also been developed in order to study rotational spectroscopy of transient species: high temperature light molecules and small radicals.

Íons polihalogenados de Si, X3Si+ (X = F, Cl), são fragmentos facilmente gerados em espectrometria de massas por ionização eletrônica de compostos de silício polihalogenados. Estes cátions possuem um elevado caráter eletrofílico e desempenham um papel importante como intermediários em processos de corrosão auxiliados por plasma utilizados na fabricação de dispositivos em microeletrônica. Esta dissertação apresenta um estudo sobre a reatividade dos íons +SiCl3, em fase gasosa, perante uma série de substratos neutros simples como água, alcoóis, amônia, aminas e algumas bases doadoras de elétrons π. As reações íon-molécula em fase gasosa foram caracterizadas do ponto de vista experimental por espectrometria de massas de ressonância ciclotrônica de íons por transformada de Fourier (FTICR) a pressões da ordem de 10-8 Torr. As reações foram acompanhadas em função do tempo de reação na cela do espectrômetro, o que permitiu a elucidação de uma série de reações sequenciais. O perfil de energia das reações e as estruturas dos íons silicênios formados nestas reações foram também caracterizados por métodos de química computacional, usando métodos ab initio e métodos baseados na teoria do funcional da densidade, a fim de elucidar o mecanismo das reações. Observou-se que o cátion +SiCl3 reage rapidamente em fase gasosa com os diversos substratos neutros através de processos semelhantes a reações de solvólise que resultam na adição do neutro seguida de eliminação de HCl. Em vários dos casos, foi possível observar a solvólise total do cátion com substituição dos três átomos de cloro. Os cálculos revelam que estas reações se processam inicialmente pela adição do eletrófilo aos centros ricos em densidade eletrônica dos substratos neutros e que estes adutos são mais estáveis que os reagentes isolados. O estado de transição destas reações envolve uma migração 1,3 de um hidrogênio e a energia calculada para o estado de transição é consideravelmente menor que a energia dos reagentes, fato este comum para reações rápidas íon/molécula em fase gasosa. Os cálculos para a espécie correspondente +CCl3 revelam que este tipo de reação não é favorável para os cátions metílicos substituídos e experimentalmente reações semelhantes não são observadas para +CCl3. No caso dos íons ClnSi(OH)3-n+ (n=1, 2 e 3), oriundos das reações de hidrólise do íon +SiCl3, observou-se reações secundárias de condensação com SiCl4 que levam a formação de espécies iônicas com ligações tipo siloxanas (-Si-O-Si-). Os cálculos teóricos sugerem que estas reações se processam inicialmente através de um intermediário tipo clorônio, R1-Cl+-R2 seguida de uma transferência formal de um átomo de Cl e rearranjo para uma estrutura tipo siloxana. / Polyhalogenated silicenium ions, X3Si+ (X = F, Cl), are common fragment ions in the mass spectra of polyhalogenated silanes obtained by electron ionization. These ions are powerful electrophiles and are believed to play a role in plasma enhanced corrosion processes and plasma enhanced chemical vapour deposition processes. In this dissertation, we present some new results on the gas-phase reactivity of the +SiCl3 ion with a number of simple n electron donor bases such as water, alcohols, ammonia, amines and some π electron donor bases. Ion-molecule reactions were characterized experimentally by Fourier transform ion cyclotron resonance mass spectrometry (FTICR) at pressures in the 10-8 Torr range. Reactions were followed as a function of trapping time of the ions in the cell of the spectrometer and this allowed for the identification of subsequent reactions of the primary product ions. The energy diagram and structure of the different silicenium ions were also characterized by computational chemistry using both ab initio and density functional theory methods in order to understand the mechanism of these reactions. +SiCl3 reacts rapidly in gas phase with various neutral substrates through processes similar to solvolysis in which the neutral substrate adds onto the silicenium ion followed by elimination of HCl. In some cases, complete solvolysis is observed with substitution of all three chlorine atoms. The calculations show that reactions proceed by initial addition of the electrophile onto the electron center of the neutral substrates giving rise to stable adducts. The transition state for these reactions involve a 1,3 hydrogen migration and the calculated energy for these transition states is less than the energy of the isolated reactants, a fact that is common to fast gas-phase ion-molecule reactions. Similar calculations for +CCl3 reveal similar solvolysis reactions to be energetically unfavourable, and in fact these reactions are not observed experimentally. Secondary reactions have been observed for the product ions ClnSi(OH)3-n+ (n = 1, 2 and 3), obtained from successive hydrolysis of +SiCl3, with the parent SiCl4 neutral. These secondary condensation reactions yield ionic species containing a siloxane type linkage (-Si-O-Si-). The theoretical calculations suggest that is that these secondary condensation reactions initially proceed via chloronium ion intermediate, R1-Cl+-R2 , followed by formal Cl transfer and rearrangement to a siloxane type structure.

Compte tenu du récent taux alarmant d'épuisement des réserves de combustibles fossiles et de l'augmentation drastique des niveaux de CO2 dans l'atmosphère qui a conduit au réchauffement de la planète et à des changements climatiques sévères, l'exploitation de toutes sortes d'énergies renouvelables a été la Parmi les principales priorités de la recherche Champs à travers le monde. L'une des nombreuses voies de ce genre est la réduction du CO2 aux combustibles utilisant des énergies renouvelables, plus communément appelées cellules photoélectro-catalytiques (PEC). Des essais expérimentaux sur la réduction du CO2 ont été réalisés sur différents types de catalyseurs dans les deux cellules (Conçu par un laboratoire) afin de comprendre la sélectivité, la productivité et les produits de réaction obtenus. Des essais expérimentaux ont été réalisés sur différents types de catalyseurs à la fois dans les cellules en phase gazeuse et en phase liquide pour comprendre la sélectivité, la productivité et les produits de réaction obtenus. Pour les études sur la réduction EC du CO2 en phase gazeuse, une série d'électrodes (à base de nanoparticules (NPs) de Cu, Fe, Pt et CuFe déposées sur des nanotubes de carbone ou de noir de carbone puis placées à l'interface entre une membrane Nafion et Une électrode à couche de diffusion de gaz). Les résultats démontrent le type divers de produits formés et leurs productivités. Dans des conditions sans électrolyte, la formation de produits ≥C1 tels que l'éthanol, l'acétone et l'isopropanol a été observée la plus élevée étant pour Fe et suivie de près par Pt. Pour améliorer Combustibles nets, un ensemble différent d'électrodes a été préparé sur la base de revêtements MOF de type imidazolate de type zéolitique substitué (SIM-1) (Fe-CNT, Pt-CNT et CuFe-CNT basés sur MOF) Et Pt-MOF a montré des carburants améliorés. En se reportant aux études sur la réduction EC du CO2 dans une cellule en phase liquide, un ensemble similaire d'électrodes a été prepare (NP - Cu, Fe, Pt, Ru, Co déposées sur des nanotubes de carbone ou du noir de carbone ont). Pour les conditions de phase liquide, en termes de produits C nets, les électrodes catalytiques à base de Pt sont en tête de la catégorie, suivies de près par Ru et Cu, tandis que Fe a obtenu la position la plus basse. Le mécanisme réactionnel sous-jacent probable a également été fourni. Afin d'améliorer encore les performances, on a synthétisé des NP de metal (Ru, Fe, Pt et Cu) de différentes tailles en utilisant différentes techniques de synthèse: (i) l'itinéraire d'imprégnation (ImR) pour obtenir des NP dans la plage de tailles de 10 à 50 nm; (Ii) Approche organométallique (OM) pour synthétiser des NPs uniformes et ultrafines dans la plage de tailles de 1-5 nm. Fe ont été synthétisés par une nouvelle voie de synthèse et des conditions pour atteindre des NP de 1 à 3 nm. (Iii) Approche de haut en bas de Nanowire pour obtenir des NP de cuivre ultrafin dans la plage de taille de 2-3,8 nm. Les améliorations apportées à la productivité du carburant se sont révélées être de 5 à 30 fois plus élevées pour les petites NP sur les NP plus importantes et, en outre, une charge réduite de 10 à 1-2% en poids. Un autre ensemble d'électrodes à base de nano-mousses (Cu NF et Fe NF sur Feuille de Cu, Feuille de Foie, Al Foil, Inconel foil et Al grid / mesh) préparés par électrodéposition ont également été étudiés afin d'améliorer encore la conversion de CO2 / carburant. Après, l'optimisation du dépôt et de la tension à l'aide de la voltamétrie cyclique, les carburants se sont améliorés de 2 à 10 fois par rapport aux combustibles nets les plus élevés obtenus à l'aide d'électrodes CNT dopées à base de NP / In view of the recent alarming rate of depletion of fossil fuel reserves and the drastic rise in the CO2 levels in the atmosphere leading to global warming and severe climate changes, tapping into all kinds of renewable energy sources has been among the top priorities in the research fields across the globe. One of the many such pathways is CO2 reduction to fuels using renewable energies, more commonly referred as photo-electro-catalytic (PEC) cells. Experimental tests were carried out on various types of catalysts in both the gas and liquid phase cells (lab-designed) to understand the different selectivity, productivity and the reaction products obtained. For the studies on the EC reduction of CO2 in gas phase cell, a series of electrodes (based on Cu, Fe, Pt and Cu/Fe metal nanoparticles – NPs - deposited on carbon nanotubes – CNTs - or carbon black and then placed at the interface between a Nafion membrane and a gas-diffusion-layer) were prepared. Under gas phase, the formation of ≥C1 products (such as ethanol, acetone and isopropanol) were observed, the highest being for Fe and closely followed by Pt, evidencing that also non-noble metals can be used as efficient catalysts under these conditions. To enhance the net fuels, a different set of electrodes were also prepared based on substituted Zeolitic Imidazolate (SIM-1) type MOF coatings (MOF-based Fe-CNTs, Pt-CNTs and Cu/Fe-CNTs) and Pt-MOF showed improved fuels. Moving to the studies on the EC reduction of CO2 in liquid phase cell, a similar set of electrodes were prepared (metal NPs of Cu, Fe, Pt, Ru and Co deposited on CNTs or carbon black). For liquid phase conditions, in terms of net C-products, catalytic electrodes based on Pt topped the class, closely followed by Ru and Cu, while Fe got the lowest position. The probable underlying reaction mechanism was also provided. In order to improve further the performances, varied sized metal NPs (Ru, Fe, Pt and Cu) have been synthesized using different techniques: (i) impregnation (ImR) route to achieve NPs in the size range of 10-50 nm; (ii) organometallic (OM) approach to synthesize uniform and ultrafine NPs in the size range of 1-5 nm (i.e., Fe NPs were synthesized through a novel synthesis route to attain 1-3 nm NPs); (iii) Nanowire (NW) top-down approach to obtain ultrafine copper metal NPs in the size range of 2-3.8 nm. The enhancements in the fuel productivity were found to be 5-30 times higher for the smaller metal NPs over the larger metal NPs and moreover, with reduced metal loading from 10 to 1-2 wt %. A different set of electrodes based on nano-foams (Cu NF and Fe NF on Cu foil, Fe foil, Al foil, Inconel foil and Al grid/mesh) prepared via electro-deposition were also investigated, to further improve CO2 to fuels conversion. After, optimization of deposition and voltage using cyclic voltammetry, the fuels improved by 2-10 times over the highest net fuels achieved using metal NPs doped CNT electrodes

<p>In this thesis, methods for studying different aspects of proteomics were developed with Fourier Transform Ion Cyclotron Resonance, (FTICR), mass spectrometry. The FTICR technique provides ultra-high mass resolving power, mass accuracy at sub ppm level and sensitivity in the attomole region.</p><p>Methods for quantifying biomarkers in body fluids such as cerebrospinal fluid, (CSF), and plasma were developed. Two sets of global markers with different properties were used for quantitative analysis; S-Methyl Thioacetimidate, (SMTA), and S-Methyl Thiopropionimidate, (SMTP), and [H₄]- and [D₄]-1-Nicotinoyloxy succinimide ester. Reduced ion suppression and higher sensitivity was obtained by coupling a High Performance Liquid Chromatography, (HPLC), system to the FTICR mass spectrometer.</p><p>In body fluids, proteins and peptides are present in a broad dynamic concentration range. Therefore, depleting abundant proteins prior to analysis results in decreased ion suppression and increased sensitivity. Two commercial depletion kits were evaluated with the SMTA- and SMTP-markers.</p><p>For both types of global markers, the experimental error for quantitative analysis of abundant proteins was less than 30%. This provides a lower limit for the protein up- and down regulations in complex solutions that can be monitored with HPLC-FTICR mass spectrometry.</p><p>Together with the identity and quantity of selected proteins the structure, dynamics and interactions with other molecules are of great importance. The later can be elucidated with Hydrogen/Deuterium Exchange, (HDX), mass spectrometry. Structural information at high resolution can be obtained with Collision-Induced Dissociation, (CID), HDX mass spectrometry. In this thesis, exchange rates of amide hydrogens in peptides were in excellent agreement with NMR results.</p><p>In some cases, the CID-fragments have different gas-phase exchange properties and as a consequence the solution phase exchange process can not be monitored. By applying Electron Capture Dissociation, (ECD), at ultra-high vacuum, the exchange process at a specific residue could be monitored.</p>

In this thesis, methods for studying different aspects of proteomics were developed with Fourier Transform Ion Cyclotron Resonance, (FTICR), mass spectrometry. The FTICR technique provides ultra-high mass resolving power, mass accuracy at sub ppm level and sensitivity in the attomole region. Methods for quantifying biomarkers in body fluids such as cerebrospinal fluid, (CSF), and plasma were developed. Two sets of global markers with different properties were used for quantitative analysis; S-Methyl Thioacetimidate, (SMTA), and S-Methyl Thiopropionimidate, (SMTP), and [H4]- and [D4]-1-Nicotinoyloxy succinimide ester. Reduced ion suppression and higher sensitivity was obtained by coupling a High Performance Liquid Chromatography, (HPLC), system to the FTICR mass spectrometer. In body fluids, proteins and peptides are present in a broad dynamic concentration range. Therefore, depleting abundant proteins prior to analysis results in decreased ion suppression and increased sensitivity. Two commercial depletion kits were evaluated with the SMTA- and SMTP-markers. For both types of global markers, the experimental error for quantitative analysis of abundant proteins was less than 30%. This provides a lower limit for the protein up- and down regulations in complex solutions that can be monitored with HPLC-FTICR mass spectrometry. Together with the identity and quantity of selected proteins the structure, dynamics and interactions with other molecules are of great importance. The later can be elucidated with Hydrogen/Deuterium Exchange, (HDX), mass spectrometry. Structural information at high resolution can be obtained with Collision-Induced Dissociation, (CID), HDX mass spectrometry. In this thesis, exchange rates of amide hydrogens in peptides were in excellent agreement with NMR results. In some cases, the CID-fragments have different gas-phase exchange properties and as a consequence the solution phase exchange process can not be monitored. By applying Electron Capture Dissociation, (ECD), at ultra-high vacuum, the exchange process at a specific residue could be monitored.

Early transition metal oxide clusters have been a focus of study for several years. The production of vanadium oxide cluster anions in a pulsed helium flow reactor provides a relatively precise way of introducing defect sites and controlling the oxidation state of the vanadium atoms. The composition of the clusters can be changed from the V2O5 stoichiometry, where the vanadium atom is in a +5 oxidation state, to more reduced stoichiometries yielding a mixture of oxidation states containing atoms in the +2 oxidation state. The subsequent addition of reactant gases such as H2O and SO2 yields very intense adsorption reactions as well as a demonstration of the robustness of particular defect free clusters. For example, the cluster has been identified as a defect free cluster where all vanadium atoms are in the +5 oxidation state and all oxygen atoms are predicted to be in the 2- state. The cluster has been shown to not adsorb SO2- while clusters in a reduced oxidation state, such as and readily adsorb one or more SO2 molecules. The adsorption process has been shown to be size dependent, with the smallest monovanadium oxide anions being the most reactive.

Among the various heterogeneous catalytic reactions three way catalysis (TWC), catalytic combustion of hydrogen, water gas shift reaction (WGS) and preferential oxidation of CO (PROX) in the hydrogen rich stream are some of the important reactions receiving the attention presently. Three-way catalysis (TWC) involves simultaneous removal of the three pollutants (i.e., CO, NOx, and HCs) from the automobile exhaust. Catalytic combustion of hydrogen by oxygen or hydrogen-oxygen recombination reaction is an industrially important reaction. It has variety of application such as in sealed lead acid batteries and nuclear reactors. Water gas shift (WGS) reaction is of specific importance to produce hydrogen from carbonaceous material. PROX is an important step to further purify hydrogen produced form WGS. Hydrogen purified using PROX can be directly fed to polymer electrolyte membrane fuel cells. By and large, noble metals Pt, Pd, Rh, Ru and some of their alloys are dispersed on oxide or high surface area carbon are the active catalysts. An alternative approach can be to make Pt2+, Pd2+, Rh3+, Ru4+ ions substituted in reducible support such as CeO2, Ce1-xTixO2-δ and TiO2 to increase the dispersion and bring down the cost. In this thesis we have followed this new approach and show that noble metal ionic catalysts are superior to noble metal nano particles. In the 1st chapter we present an overview of heterogeneous catalysis and important heterogeneous catalytic reactions. Monolithic catalyst and various ways to coat catalysts for application have been reviewed. Metal-support interaction till date is also reviewed. In the 2nd chapter, synthesis of noble metal ionic catalysts by solution combustion method is described. Coating of washcoat and active catalyst phase over ceramic honeycomb by a new combustion method is described. Solution combustion reaction and characterization of the catalyst by x-ray diffraction, x-ray photoelectron spectroscopy, temperature programmed reduction and reaction is given. We have fabricated experimental systems to carryout catalytic reaction and in this chapter they have been presented. In the 3rd chapter, we report a new process of coating of active exhaust catalyst over -Al2O3 coated cordierite honeycomb. The process consists of (a) growing  -Al2O3 on cordierite by solution combustion of Al(NO3)3 and oxylyldihydrazide (ODH) at 600 0C. Active catalyst phase, Ce0.98Pd0.02O2- is coated on - Al2O3 coated cordierite again by combustion of ceric ammonium nitrate and ODH with 1.2  10-3 M PdCl2 solution at 500 0C. In this way a coat layer over cordierite ceramic has been achieved and catalyst has the active sites in the form of Pd2+ ions rather than Pd metal. Weight of the active catalyst can be varied from 0.02 to 2 wt% which is sufficient but can be loaded even up to 12 wt% by repeating dip dry combustion [1]. Adhesion of catalyst to cordierite surface is via oxide growth on oxide ceramic which is very strong. 100 % conversion of CO is achieved below 80 oC at a space velocity of 880 h-1. At much higher space velocity of 21000h-1, 100 % conversion is obtained below 245 oC. Activation energy for CO oxidation is 8.4 kcal/mol. At a space velocity of 880 h-1 100% NO conversion is attained below 185 oC and 100 % conversion of ‘HC’(C2H2) below 220 oC. At the same space velocity 3-way catalytic performance over Ce0.98Pd0.02O2- coated monolith shows 100% conversion of all the pollutants below 220 o C with 15% excess oxygen. Catalytic activity of cordierite honeycomb coated by this new coating method for the oxidation of major hydrocarbons in exhaust gas is discussed further in this chapter. ‘HC’ oxidation over the monolith catalyst is carried out with a mixture having the composition, 470 ppm of both propene and propane and 870 ppm of both ethylene and acetylene with the varying amount of O2. 3-way catalytic test is done by putting hydrocarbon mixture along with CO (10000ppm), NO (2000ppm) and O2 (15000ppm). Below 350 oC full conversion is achieved [2]. A comparison of the results shows that Ce1-xPdxO2-δ far superior to other catalysts. In this method, handling of nano material powder is avoided. In the 4th chapter we present a detailed study on the catalytic combustion of hydrogen by oxygen (hydrogen oxygen recombination reaction). Ever since Michel Faraday showed H2 + O2 recombination reaction over platinum metal plates, Pt metal has remained the only room temperature recombination catalyst. In search of an alternative catalyst, we discovered a new Pt free Ti0.99Pd0.01O2- compound which shows high rates of this reaction above 45 oC compared to Ce0.98Pt0.02O2-, Pt/Al2O3 and Pd/Al2O3. High rates of H2+O2 recombination over Pt and Pd ion respectively in CeO2 and TiO2 is due to the protonic type H2+ adsorption on Pt2+ or Pd2+ and dissociative chemisorption of O2 on the electron rich oxide ion vacancies [3]. In the case of Ce0.98Pt0.02O2-, H2/Pt ratio in a TPR experiment is ~2.3 at 0 oC. In the case of Ti0.99Pd0.01O2- also, H2 adsorption occurs below 0 oC and H2 / Pd ratio is ~2.2. Thus, more than 4-5 H atoms are adsorbed per metal ion. This is attributed to hydrogen spillover. H2 is known to be adsorbed as hydride ion (H-) over Pt, Pd, Rh, Ru, Os and Ir metals. Proton NMR studies of H2 adsorbed on Pd metal have shown upfield i.e. negative shift of 12 ppm with respect to TMS. We have studied proton NMR of Ti0.99Pd0.01O2- + H2 which show a downfield shift of 11.35 ppm confirming H+ or H2+ kind of species over Pd2+ ion in Ti0.99Pd0.01O2-. In Ce0.98Pt0.02O2- also H2 adsorption led to H2+ like species observed at 8 ppm and DFT calculations indeed showed H2+ kind species. H2+ is a precursor for dissociation and can readily induce O2 dissociation leading to high rates of recombination. In the 5th chapter we report water gas shift reaction (WGS) and preferential oxidation of CO (PROX) over Ti0.99Pt0.01O2-, Ce0.83Ti0.15Pt0.02O2- and Ce0.98Pt0.02O2-δ. The water gas shift reaction (WGS) is an important reaction to produce hydrogen. In this study, we have synthesized nano crystalline catalysts where Pt ion is substituted in the +2 state in TiO2, CeO2 and Ce1-xTixO2-δ. The catalysts have been characterized by X-ray diffraction and X-ray photoelectron spectroscopy (XPS) and it has been shown that Pt2+ ions in these reducible oxides of the form Ti0.99Pt0.01O2-, Ce0.83Ti0.15Pt0.02O2- and Ce0.98Pt0.02O2-δ are highly active. These catalysts were tested for the water gas shift reaction both in presence and absence of hydrogen. It is shown that Ti0.99Pt0.01O2- exhibits higher catalytic activity than Ce0.83Ti0.15Pt0.02O2- and Ce0.98Pt0.02O2-δ [4]. Further, experiments were conducted to determine the deactivation of these catalysts by performing the daily startup and shutdown of the reactor for over 24 hours. There was no sintering of Pt and no carbonate formation and, therefore, the catalyst did not deactivate even after prolonged reaction. There was no carbonate formation because of the highly acidic nature of Ce4+, Ti4+ ions in the catalysts. Further, PROX activity of these catalysts has been studied. Ce0.83Ti0.15Pt0.02O2- and Ce0.98Pt0.02O2-δ showed high activity, large operating temperature window and low working temperature proving them to be highly effective PROX catalysts. In the 6th chapter we study the electrocatalysis of formic acid electro-oxidation and simultaneously mapping the electronic states of the electrodes by X-ray photoelectron spectroscopy (XPS). Ionically dispersed platinum in Ce1-xPtxO2-δ and Ce1-x-yTiyPtxO2-δ is very active towards oxygen evolution and formic acid oxidation. Higher electro-catalytic activity of Pt2+ ions in CeO2 and Ce1-xTixO2 compared to Pt0 in Pt/C is due to Pt2+ ion interaction with the supports, CeO2 and Ce1-xTixO2 respectively [5]. Further, ionic platinum does not suffer from CO poisoning effect unlike Pt0 in Pt/C. Utilization of lattice oxygen from the electrodes during the reaction has been demonstrated. This lattice oxygen exchange is responsible to convert CO to CO2 in the lower potential region to remove CO poisoning effect. In 7th chapter we repeat our study on the noble metal ion reducible oxide interaction in Ce1-xPtxO2- and Ce1-xPdxO2- (x= 0.02) system by a novel electrochemical method combined with XPS. Working electrodes made of CeO2 and Ce0.98Pt0.02O2- mixed with 30% carbon are cycled between 0.0-1.2 V in potentio-static (chronoamperometry) and potentio-dynamic (cyclic voltametry) mode with reference to saturated calomel electrode (SCE). Reversible oxidation of Pt0 to Pt2+ and Pt4+ state due to the applied positive potential is coupled to simultaneous reversible reduction of Ce4+ to Ce3+ state. CeO2 reduces to CeO2-y (y= 0.35) after applying +1.2 V which is not reversible. But Ce0.98Pt0.02O2- reaches a steady state with Pt2+: Pt4+ in the ratio of 0.60: 0.40 and Ce4+: Ce3+ in the ratio of 0.55: 0.45 giving a composition Ce0.98Pt0.02O1.74 at 1.2 V which is reversible [6]. Composition of Pt ion substituted compound is reversible between Ce0.98Pt0.02O1.95 to Ce0.98Pt0.02O1.74 within the potential range of 0.0-1.2 V. Thus, Ce0.98Pt0.02O2- forms a stable electrode for oxidation of H2O to O2 unlike CeO2. A linear relation between oxidation of Pt2+ to Pt4+ with simultaneous reduction of Ce4+ to Ce3+ is observed demonstrating Pt-CeO2 metal support interaction is due to reversible Pt0/Pt2+/Pt4+ interaction with Ce4+/Ce3+ redox couple. Similar studies have been performed with Ce0.98Pd0.02O2- catalyst to show the redox coupling between Pd2+/Pd0 and Ce4+/Ce3+ redox couples. We expect similar redox coupling for Pd, Pt ions substituted TiO2, and Ce1-xTixO2. In the final chapter 8, a critical review and conclusion on the results presented in the thesis is presented. The combustion synthesized catalysts reported in this thesis stabilizes the Pt and Pd metals in their ionic state rather than zero valent metallic state. Thus, the catalysts are uniform solid catalysts. High activity and stability of these catalysts are shown to be due to the electronic interaction between noble metal ions and the reducible oxide. Redox couples Pt0/Pt2+, Pt2+/Pt4+ and Pd0/Pd2+ interact with Ce4+/Ce3+, Ti4+/Ti3+ couples such that metal is oxidized and the support is reduced. This has been established in the thesis by a combined use of electrochemistry and XPS thus solving a long standing problem of metal support interaction in catalysis. We hope that the results presented in the thesis is a worthwhile contribution to catalysis. (For mathematical equations pl refer pdf file.)

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In der vorliegenden Arbeit wird das Konzept einer druckbasierten Analyse von Fest-Gas-Gleichgewichten hinsichtlich theoretischer wie experimenteller Zusammenhänge untersucht. Hierfür erfolgt eine gezielte Nutzung der Beziehungen von theoretischen und experimentell zugänglichen physikalischen Parametern, um so die Grundlage für eine spätere Anwendung im Kontext der Syntheseplanung zu ermöglichen. Im Speziellen handelt es sich im vorgestellten Konzept um die aus festkörperanalytischer Sicht häufig vernachlässigte Beziehung zwischen dem Dampfdruck von Festkörpern und dem chemischen Potenzial. Neben der theoretischen Erarbeitung des Analysekonzeptes befasst sich die vorgestellte Arbeit zusätzlich mit dessen experimenteller Umsetzung anhand der Entwicklung bzw. Optimierung der Analyseverfahren der Hochtemperatur-Gasphasenwaage sowie des automatisierten Membrannullmanometers. Abgeschlossen wird die Arbeit zudem durch die anschauliche Vorstellung der praktischen Anwendung des Konzeptes hinsichtlich unterschiedlicher Fragestellungen (Theorie vs. Experiment: Quecksilber/Phosphor/Iod, Analyse der Phasenbildung: Arsen/Phosphor, rationale Syntheseplanung: IrPTe, Syntheseoptimierung: Bi13P3I7, Kinetik: FeAs).