京都大学 / 新制・課程博士 / 博士(人間・環境学) / 甲第24711号 / 人博第1084号 / 新制||人||254(附属図書館) / 2022||人博||1084(吉田南総合図書館) / 京都大学大学院人間・環境学研究科相関環境学専攻 / (主査)教授 吉田 寿雄, 教授 田部 勢津久, 教授 中村 敏浩, 教授 田中 庸裕 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DFAM

Les catalyseurs hétérogènes sont des matériaux complexes dont les structures peuvent être modifiées en cours de fonctionnement. Une meilleure compréhension des relations entre propriétés catalytiques et propriétés structurales est nécessaire pour répondre à de nouveaux enjeux environnementaux et économiques. Seules les caractérisations in situ résolues dans le temps i.e. dans des conditions réelles, permettent d'apporter ces informations. Dans ce travail, nous nous sommes intéressés à la caractérisation operando par spectroscopie d'absorption des rayons X (XAS) résolue dans le temps de deux types de catalyseurs hétérogènes : les catalyseurs Fischer-Tropsch et les catalyseurs d'hydrodésulfuration. Si ces catalyseurs sont connus depuis de nombreuses années, peu de caractérisations sont réalisées in situ ou operando au cours de la réaction.Etant données leurs conditions réactionnelles (haute température et haute pression), la mise en œuvre de ces caractérisations a nécessité tout d'abord la construction des outils nécessaires à la caractérisation in situ de catalyseurs hétérogènes sous haute pression de gaz. Ensuite, nous avons réuni un ensemble cohérent de techniques de caractérisation autour du catalyseur Fischer-Tropsch afin de permettre son étude structurale à différentes échelles : l'ordre local avec le Quick-EXAFS et l'ordre à grande distance avec la diffraction des rayons X. Afin d'observer l'effet de la forme cristalline de la phase active sur les propriétés catalytiques, nous avons pour un même catalyseur, activé selon deux voies d'activation, quantifié son activité au moyen de la spectroscopie Raman et la spectrométrie de masse. D'autre part, la caractérisation simultanée de deux centres métalliques, accessible par le dispositif QEXAFS installé sur la ligne de lumière SAMBA, a permis d'obtenir une description fine des processus d'activation des catalyseurs bimétalliques d'hydrodésulfuration. Notre étude s'est portée, sur la comparaison de catalyseurs de même formulation avec des prétraitements différents (séché/calciné) et de deux catalyseurs promus par des métaux différents : le cobalt et le nickel.

Printed circuit board manufacturing involves subtractive copper (Cu) etching where fine features are developed with a specific spatial resolution and etch profile of the Cu interconnects. A UV-Vis ATR metrology, to characterize the chemical transitions, has been developed to monitor the state of the bath by an in-situ measurement. This method provides a direct correlation of the Cu etch bath and was able to predict a 35% lower etch rate that was not predicted by the three current monitoring methods (ORP, specific gravity, and conductivity). Application of this UV-Vis ATR probe confirmed that two industrial etch baths, in identical working conditions, confirmed a difference in Cu2+ concentration by the difference of the near IR 860nm peak. The scope of this probe allowed chemically specific monitoring of the Cu etch bath to achieve a successful regeneration for repeated use. Interlayer dielectrics (ILDs) provide mechanical and electrical stability to the 3D electrical interconnects found in IC devices. It is particularly important that the structural support is created properly in the multilayered architecture to prevent the electrical cross signaling in short range distances. A combined multiple internal reflection and transmission FTIR has been employed for the characterization of silicon oxycarbonitride (SiOCN) films. These dielectric low-k films incorporate various functional groups bonded to silicon and require chemical bonding insight in the transformation and curing process. Distinct SiOx bonding patterns were differentiated, and the structure of the films can be predicted based on the amount of Si network and caged species. Further optimization of the FTIR analysis must minimize interference from moisture that can impact the judgement of peak heights. To accommodate this, a high-quality glove box was designed for dry air feedthrough to achieve a 95% moisture reduction during analysis, where less than 0.1 mAbs of moisture is detected in the spectra (without additional correction). The glove box allows for the rapid analysis of multiple sample throughput to outpace alternative characterization methods while retaining low spectral noise and a dry environment for 24/7 analysis. There is a great need to identify new catalysts that are suitable for tackling current economic demands, one of which is the nitrogen reduction reaction (NRR). The development of the surface enhanced infrared absorption spectroscopy (SEIRAS) has been applied to characterize the NRR mechanisms on the vanadium oxynitride electrocatalyst. Electrochemical measurements demonstrate NRR activity that is up to three times greater in the presence of N2 than the control Ar. FTIR operando suggests that a considerable number of intermediates were formed and continued to increase in absorbing value under an applied potential of -0.8 V vs Ag/AgCl. XPS results of the post-NRR film suggest a restricting of the film where vanadium oxynitride films are prone to instabilities under the possible MvK mechanism. After 90 minutes of NRR, the NH3 generated was approximately 0.01 ppm was calculated for through the salicylate colorimetric method. On-going efforts are focusing on optimizing the vanadium oxynitride film by the tuning of the oxynitride ratios and crystalline properties to promote the formation of V≡N: during the nitrogen reduction reaction.

Supported noble metal catalysts make the best utilization of noble metal atoms. Recent advances in nanotechnology have brought many attentions into the rational design of catalysts in the nanometer and subnanometer region. Recent studies showed that catalysts in the subnanometer regime could have extraordinary activity and selectivity. However, the structural performance relationships behind their unique catalytic performances are still unclear. To understand the effect of particle size and shape of noble metals, it is essential to understand the fundamental reaction mechanism. Single atoms catalysts and subnanometer clusters provide a unique opportunity for designing heterogeneous catalysts because of their unique geometric and electronic properties. CO oxidation is one of the important probe reactions. However, the reaction mechanism of noble single atoms is still unclear. Additionally, there is no agreement on whether the activity of supported single atoms is higher or lower than supported nanoparticles. In this study, we applied different operando techniques including x-ray absorption fine structure (XAFS), diffuse reflectance infrared spectroscopy (DRIFTS), with other characterization techniques including calorimetry and high-resolution scanning transmission electron microscopy (STEM) to investigate the active and stable structure of Ir/MgAl2O4 and Pt/CeO2 single-atom catalysts during CO oxidation. With all these characterization techniques, we also performed a kinetic study and first principle calculations to understand the reaction mechanism of single atoms for CO oxidation. For Ir single atoms catalysts, our results indicate that instead of poisoning by CO on Ir nanoparticles, Ir single atoms could adsorb more than one ligand, and the Ir(CO)(O) structure was identified as the most stable structure under reaction condition. Though one CO was strongly adsorbed during the entire reaction cycle, another CO could react with the surface adsorbed O* through an Eley-Rideal reaction mechanism. Ir single atoms also provide an interfacial site for the facile O2 activation between Ir and Al with a low barrier, and therefore O2 activation step is feasible even at room temperature. For Pt single-atom catalysts, our results showed that Pt(O)3(CO) structure is stable in O2 and N2 at 150 °C. However, when dosing CO at 150 °C, one surface O* in Pt(O)3(CO) could react with CO to form CO2, and the reacted O* can be refilled when flowing O2 again at 150 °C. This suggests that an adsorbed CO is present in the entire reaction cycle as a ligand, and another gas phase CO could react with surface O* to form CO2 during low-temperature CO oxidation. Supported single atoms synthesized with conventional methods usually consist of a mixture of single atoms and nanoparticles. It is important to quantify the surface site fraction of single atoms and nanoparticles when studying catalytic performances. Because of the unique reaction mechanism of Ir single atoms and Ir nanoparticles, we showed that kinetic measurements could be applied as a simple and direct method of quantifying surface site fractions. Our kinetic methods could also potentially be applied to quantifying other surface species when their kinetic behaviors are significantly different. We also benchmarked other in-situ and ex-situ methods of quantifying surface site fraction of single atoms and nanoparticles. To bridge the gap between single atoms and nanoparticles and have a better understanding of the effect of nuclearity on CO oxidation, we also studied supported Ir subnanometer clusters with the average size less than 0.7 nm (< 13 atoms) prepared by both inorganic precursor and organometallic complex Ir4(CO)12. Low-temperature CO adsorption indicates that CO and O2/O could co-adsorb on Ir subnanometer clusters, however on larger nanoparticle the particle surface is covered by CO only. Additional co-adsorption of CO and O2 was studied by CO and O2 calorimetry at room temperature. CO oxidation results showed that Ir subnanometer clusters are more active than Ir single atoms and Ir nanoparticles at all conditions, and this could be explained by the competitive adsorption of CO and O2 on subnanometer clusters. / Doctor of Philosophy / CO oxidation is one of the important reactions in catalytic converters. Three-way catalysts, typically supported noble metals, are very efficient at high temperature but could be poisoned by CO at cold start. Better designed catalysts are required to improve the performance of the catalytic converter to lower the emissions of gasoline engines. To reach this goal, more efficient use of the noble metal is required. Single-atom catalysts consist of isolated noble metal atoms supported on different supports, which provide the best utilization of noble metal atoms and provides a new opportunity for a better design of heterogeneous catalysts. The unique electronic and geometric properties of metal single atoms catalysts could lead to a better activity and selectivity. Subnanometer clusters have also been shown to have unique electronic properties. With a better understanding of the structure of supported single atoms and subnanometer clusters, their catalytic performance can be optimized for better catalysts in the catalytic converter and other applications. In this work, we applied in-situ and operando characterization, kinetic studies and first principle calculations aiming to understand the active and stable structure of noble metal single atoms and vi subnanometer clusters under reaction condition, and their reaction mechanisms during CO oxidations. For MgAl₂O₄ supported Ir single atoms, our results suggest that CO could be co-adsorbed with O₂/O under reaction conditions. These multiple ligands adsorption leads to a unique reaction mechanism during CO oxidation. Though one CO was adsorbed during the whole reaction cycle, another gas phase CO could react with the O* species co-adsorbed with CO through an Eley-Rideal mechanism. This suggests that Ir single atoms are no longer poisoned by CO, and on the other hand the O₂ can be activated on an interfacial site with a low reaction barrier. Ir subnanometer clusters showed higher activities than Ir single atoms and nanoparticles. In-situ IR and high energy resolution fluorescence detected – X-ray absorption near edge spectroscopy (HERFD-XANES) showed that CO could co-adsorb with O₂ at room temperature, and this competitive adsorption could explain the high activity during CO oxidation. Supported Ir single atoms and subnanometer clusters are not poisoned by CO and O₂ could be co-adsorbed, this could be potentially applied to solve the poisoning of catalyst in the catalytic converter at cold start temperature. We also performed kinetic study on CeO₂ supported Pt single atoms. Similar behavior was observed, and we showed that the CO and O co-adsorbed complex is stable in O₂ and N₂, but could react in CO. With the understanding of the active structure of noble metal single atoms and the origin of activities, better-designed catalysts can be synthesized to improve the activity and selectivity of low-temperature oxidation reactions.

[ES] El etileno representa uno de los pilares de la industria química actual como parte de los denominados "productos químicos básicos". Los procesos de recuperación y valorización de etileno actuales están basados en fuentes de carbono de origen fósil y son operados a gran escala, por lo que tienen asociado un elevado coste energético y contribuyen significativamente a la emisión de gases de efecto invernadero. La preocupación actual por avanzar hacia la descarbonización de la industria química ha impulsado el diseño de procesos químicos más sostenibles. En este contexto, el diseño de nuevos procesos catalíticos (tándem), con alta economía atómica y operando a condiciones de operación más suaves, supone una alternativa de gran interés. La presente tesis doctoral se centra en el desarrollo de procesos catalíticos alternativos para la conversión de (bio-)etileno en productos de alto valor añadido, como el propileno o los compuestos oxigenados C3. En primer lugar, se ha estudiado el efecto de emplear diferentes soportes basados en óxidos metálicos en catalizadores de Rh de dispersión atómica para la hidroformilación de etileno en fase gas para producir propanal. Entre los materiales estudiados con diferente grado de reducibilidad superficial, el catalizador Rh1/SnO2 mostró el mejor rendimiento, con altos valores de actividad y con una selectividad a hidroformilación prácticamente total, a unas condiciones de operación muy suaves (P=20 bar, T=383 K). El comportamiento extraordinario de este material se ha atribuido a la capacidad de formar vacantes de oxígeno superficiales, lo que facilita la formación de especies de Rh de alta flexibilidad de coordinación y con propiedades electrónicas que se asemejan a de los catalizadores moleculares en disolución empleados industrialmente. A continuación, se estudió el uso de catalizadores bimetálicos Ag-Pt para la hidrogenación selectiva de aldehídos en presencia de olefinas. Para la composición óptima del catalizador (<4 at% Pt), se descubrió que las especies de Pt estaban altamente dispersas sobre la matriz de Ag, posiblemente en forma de las denominadas "aleaciones de átomos aislados". Dicho catalizador se combinó junto al catalizador de hidroformilación altamente selectivo Rh1/SnO2 en un proceso de hidroformilación reductiva, que permitió la conversión directa de etileno a 1-propanol con selectividad prácticamente total (98%) a conversiones de etileno >50%. Por último, se estudió la conversión de etileno a propileno mediante procesos tándem de dimerización-metátesis. Para ello, se estudiaron métodos de calentamiento específico y termometría selectiva combinando técnicas de calentamiento por inducción y termometría por luminiscencia. Dichos métodos resultaron adecuados para solventar las incompatibilidades de temperatura inherentes a los procesos de catálisis tándem del estado del arte y desbloquear, de esta manera, rendimientos inaccesibles para procesos operados mediante calentamiento convencional. / [CA] L'etilè representa un dels pilars de la indústria química actual com a part dels denominats "productes químics bàsics". Els processos de recuperació i valorització d'etilé actuals estan basats en fonts de carboni d'origen fòssil i són operats a gran escala, per la qual cosa tenen associat un elevat cost energètic i contribueixen significativament a l'emissió de gasos d'efecte d'hivernacle. La preocupació actual per avançar cap a la descarbonització de la indústria química requereix el disseny de processos químics més sostenibles. En este context, el disseny de nous processos catalítics (tàndem), amb alta economia atòmica i operant a condicions d'operació més suaus, suposa una alternativa de gran interés. La present tesi doctoral se centra en el desenvolupament de processos catalítics alternatius per a la conversió de (bio-)etilè en productes d'alt valor afegit, com el propilé o els compostos oxigenats C3. En primer lloc, s'ha estudiat l'efecte d'utilitzar diferents suports basats en òxids metàllics en catalitzadors de Rh de dispersió atòmica per a la *hidroformilación d'etilè en fase gas per a produir probresca. Entre els materials estudiats amb diferent grau de reducibilidad superficial, el catalitzador Rh1/SnO2 va mostrar el millor rendiment, amb alts valors d'activitat i amb una selectivitat a hidroformilació pràcticament total, a unes condicions d'operació molt suaus (P=20 bar, T=383 K). El comportament extraordinari d'este material s'ha atribuït a la capacitat de formar vacants d'oxigen superficials, la qual cosa facilita la formació d'espècies de Rh d'alta flexibilitat de coordinació i amb propietats electròniques que s'assemblen a dels catalitzadors moleculars en dissolució utilitzats industrialment. A continuació, es va a estudiar l'ús de catalitzadors bimetàl·lics Ag-Pt per a la hidrogenació selectiva d'aldehids en presència d'olefines. Per a la composició òptima del catalitzador (<4 at% Pt), es va descobrir que les espècies de Pt estaven altament disperses sobre la matriu de Ag, possiblement en forma dels denominats "aliatges d'àtoms aïllats". Aquest catalitzador es va a combinar al costat del catalitzador de hidroformilació altament selectiu Rh1/SnO2 en un procés de hidroformilació reductiva, que va permetre la conversió directa d'etilè a 1-propanol amb selectivitat pràcticament total (98%) a conversions d'etilé >50%. Finalment, es va a estudiar la conversió d'etilè a propilè mitjançant processos tàndem de dimerització-metàtesi. Per a això, es van a estudiar mètodes de calfament específic i termometria selectiva combinant tècniques de calfament per inducció i termometria per luminescència. Aquests mètodes van a resultar adequats per a solucionar les incompatibilitats de temperatura inherents als processos de catàlisis tàndem de l'estat de l'art i desbloquejar, d'esta manera, rendiments inaccessibles per a processos operats mitjançant calfament convencional. / [EN] Ethylene constitutes one of the pillars of the current chemical industry as part of the so-called "commodity chemicals". Current ethylene recovery and valorization technologies are based on fossil-based carbon feedstocks operated at the large scale, which are very energy-intense and contribute to important greenhouse gas emissions. The current concern on progressing towards a defossilized chemical industry calls for the design of more sustainable chemical processes. In this regard, the design of novel (tandem-) catalytic processes, with high atom economy at milder operation conditions, is desired. In this thesis, the conversion of (bio-)ethylene into high-added value chemicals such as propylene and C3 oxygenates via alternative catalytic processes is addressed. Firstly, metal oxide support effects have been explored in Rh single-atom catalysts for gas-phase ethylene hydroformylation to propanal. By exploring a series of materials with different surface reducibility, a Rh1/SnO2 catalyst showed to deliver the best performance, with high Rh-specific activity and essentially full selectivity to hydroformylation under very mild operation conditions (P=20 bar, T=383 K). The unconventional performance of this material has been ascribed to the capacity of forming surface oxygen vacancies on the SnO2 support, which triggers the formation of Rh species that resemble the electronic and coordination flexibility properties of Rh centers in benchmark molecular complexes operating in solution. Next, bimetallic Ag-Pt catalysts were explored, computationally and experimentally, for the selective hydrogenation of aldehydes in the presence of olefins under the same set of mild operation conditions. For the optimal catalyst formulation (<4 at% Pt), Pt species were highly dispersed within the Ag matrix, possibly forming a so-called "single-atom alloy". This catalyst was integrated with the fully selective hydroformylation Rh1/SnO2 catalyst in a reductive hydroformylation process, which unlocked the direct conversion of ethylene to 1-propanol with almost full selectivity (98%) at ethylene conversion >50%. Finally, the direct conversion of ethylene into propylene via tandem dimerization-metathesis has been explored. Catalyst-specific heating and thermometry methods, combining induction heating and remote luminescence thermometry, proved suitable to alleviate temperature incompatibilities inherent to state-of-the-art tandem catalytic processes and unlock catalytic performances inaccessible to conventionally heated conversion processes. / I would like to thank the Spanish Ministry of Science, Innovation and Universities (MCIU) for my FPU grant (FPU17/04701) and the European Research Council (ERC) under the Horizon 2020 research and innovation program (ERC-CoG-TANDEng; grant agreement 864195), which have made possible the realization of this thesis. I would like to thank the Institute of Chemical Technology (ITQ) and the Spanish Research Council (CSIC) for giving me access to the infrastructure I have used for my PhD work. I would like also to thank the Institute of Materials Science of Madrid (ICMM) and the Massachusetts Institute of Technology (MIT) for giving me access to their facilities during my short stays. Thanks also to the ALBA synchrotron and, particularly, to the CLÆSS beamline for making possible the access to synchrotron experiments granting us with several beamtimes. Finally I would like to thank the Chemical and Nuclear Engineering department (DIQN) of the Polytechnic University of Valencia (UPV), for hosting me as a teaching assistant during these years / García Farpón, M. (2024). Tandem Catalytic Processes for Selective Ethylene Valorization into C3 Chemicals [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/203261

Single-atom and cluster catalysts have been receiving significant interest due to not only their capability to approach the limit of atom efficiency but also to explore fundamentally unique properties. Supported Pt-group single atoms and clusters catalysts in the subnanometer size regime maximize the metal utilization and were reported to have extraordinary activities and/or selectivities compared with nanoparticles for various reactions including hydrogenation reactions. However, the relationship between metal nuclearity, electronic and their unique catalytic properties are still unclear. Thus, it is crucial to establish their relations for better future catalyst design. Ethylene hydrogenation and acetylene hydrogenation are two important probe reactions with the simplest alkene and alkyne, and they have been broadly studied as the benchmark reactions on the various catalyst systems. However, the catalytic properties and reaction mechanism of those hydrogenation reactions for metal nuclearitiy in the subnanometer regime is still not well understood. In this study, we applied different characterization techniques including x-ray absorption fine structure (XAFS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy(XPS), diffuse reflectance infrared spectroscopy (DRIFTS), calorimetry and high-resolution scanning transmission electron microscopy (STEM) to investigate the structure of Pt/TiO2 and Pd/COF single-atom catalysts and tested their catalytic properties for hydrogenation reactions. In order to develop such relations, we varied the nuclearity of Pt supported on TiO2 from single atoms to subnanometer clusters to larger nanoparticles. For acetylene hydrogenation, Pt in the subnanometer size regime exhibits remarkably high selectivity to ethylene compared to its nanoparticle counterparts. The high selectivity is resulted from the decreased electron density on Pt and destabilization of C2H4, which were rationalized by X-ray photoelectron spectroscopy and calorimetry results. On the other hand, the activity of H2 activation and acetylene hydrogenation decreased as Pt nuclearity decreased. Therefore, our results show there's a trade-off between activity and selectivity for acetylene hydrogenation. Additionally, the kinetics measurements of ethylene hydrogenation and acetylene hydrogenation were performed on Pt/TiO2 catalysts, and they found to be structure sensitive for both reactions, which the reaction orders and activation energy changes as particles size change. The activity of ethylene hydrogenation decreases, and activation energy increase from 43 to 86 kJ/mol, as Pt nuclearity decreased from an average size of 2.1 nm to 0.7 nm and single atoms. The reaction orders in hydrocarbons (ethylene and acetylene) were less negative on subnanometer clusters and single atoms in contract to nanoparticles. The results imply that hydrocarbons, ethylene and acetylene species, do not poison the catalyst on Pt in the subnanometer size regime, and hydrogen activation turn to competitive adsorption path with surface hydrocarbons species. Moreover, single atom Pd supported on imine-linked covalent organic framework was synthesized, characterized by a various of techniques including X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of adsorbed CO, and evaluated its catalytic properties for ethylene hydrogenation. The XAS results show that Pd atoms are isolated and stabilized by two covalent Pd–N and Pd-Cl bonds. DRIFTS of CO adsorption shows a sharp symmetrical peak at 2130 cm−1. The Pd single atoms are active for hydrogenation of ethylene to ethane at room temperature. The reaction orders in C2H4 and H2 were 0.0 and 0.5 suggesting that ethylene adsorption is not limiting while hydrogen forms on Pd through dissociative adsorption. / Doctor of Philosophy / More than 90% of chemicals come from petroleum and natural gas, and most of these chemicals are composed of alkene and alkyne, hydrocarbons containing at least one double bonds or triple bonds, such as ethylene, propylene, butenes, butadiene. These small hydrocarbon molecules with carbon-carbon bonds (double or triple) are in great interest of fundamental study and serve as probe units for understanding more complex reactions. Catalysts are materials that can be added to a chemical reaction to accelerate the specific rate of reactions. Most catalysts are supported noble metals thus increase the utilization of metal atoms are important. Decreasing the particle size to increase the metal dispersion is the simple approach to maximize the atom efficiency. However, it is not well understood how do the electronic property and catalytic performance change as particle size decrease. In this work, we focus on the structure sensitivity on catalysts in sub-nanometer region. Supported Pt and Pd catalysts, known to be highly active for hydrogenation reactions, are studied on hydrogenation reactions of acetylene and ethylene, the simplest alkene and alkyne. The Pd and Pt catalysts with particle sizes ranging from single atoms, sub-nanometer clusters and nanoparticles were prepared, characterized and tested for hydrogenation reactions mentioned above. The results show that significantly change in electronic property, catalytic performance (activity and/or selectivity) and reaction kinetics of the catalysts as the particle size changing from nanometer to sub-nanometer region. The fundamental understanding of structure sensitivity on catalysts and their relations between surface structure, electronic property and catalytic performance presented in this work can help the researchers design better catalysts for future work.

Dans ce travail de thèse, deux objectifs ont été fixés. Le premier a été de mieux comprendre le mécanisme très complexe qui est en jeu dans les accumulateurs Li/S. Pour cela, les modifications structurales du matériau actif ont été observées in operando et ont permis de valider un modèle clair concernant les réactions de transformations de phases qui contrôlent le lithium/soufre. La cristallisation d’une forme métastable du soufre (bêta-S8 monoclinique) en fin de recharge a ainsi été observée pour la première fois lors d’expériences au synchrotron de l’ESRF. La technique d’impédance électrochimique a également donné d’importantes informations sur les cinétiques deces réactions. Le deuxième objectif visait l’amélioration du système Li/S par l’optimisation des électrodes de soufre afin d’augmenter leurs performances mais également par la fabrication d’électrodes de Li2S efficaces permettant la transition vers le Li-ion/S, plus sécuritaire. / In this work two main aspects has been conducted in parallel. The first one was focused on betterunderstanding the very complex working mechanism of Li/S cell. Structural changes evolution ofactive material upon real time battery operation was explored, giving a clear answer on thesolid/liquid reaction evolution, which govern the electrochemistry of Li/S technology. Formationof another allotropic form of sulfur (monoclinic beta-S8) during recharging the battery have beenreported for the first time ever in Li/S community. Impedance technique applied to such systemprovided additional information concerning the kinetics of these reactions. Apart from that,another aspect targeted rather on improvements of already existing solutions (making better sulfurelectrodes, with significantly improved specific capacities) as well as development the alternativesolutions, i.e. fabrication and test of new Li2S-based positive electrodes, which could be apromising transition from classical Li/S cells into safer Li-ion/S batteries.

Chimie organométallique résonne avec catalyse homogène, et chimie des surfaces avec catalyse hétérogène. Mais la frontière établie entre ces deux domaines est en réalité très mince. Leur rapprochement aboutit dans les années 1990 au développement d’une nouvelle science : la chimie organométallique de surface, qui souligne leur complémentarité. L’objectif de cette science, dans laquelle s’inscrit ce travail de thèse, est de créer des catalyseurs hétérogènes à partir de composés organométalliques. Notre objectif est d’apporter une contribution à la compréhension de la formation de nanoparticules de platine - métal incontournable en catalyse hétérogène - sur des supports de silice amorphe, et ce grâce à la chimie organométallique. Au cours de ce travail, une palette de catalyseurs Pt/SiO2 a été préparée à partir de trois précurseurs de platine : le composé classique H2PtIVCl6.xH2O et deux composés organométalliques PtII(η 4-C8H12)Cl2 et Pt0(η 2-C7H10)3 , et de trois supports : une silice commerciale (Davison), une silice mésoporeuse SBA-15 synthétisée au laboratoire et unesilice naturelle, la diatomite. De plus, l’étude du catalyseur de référence au platine « EuroPt-1 » a permis de développer une méthodologie de suivi operando par Spectroscopie Infrarouge à Transformée de Fourier par Réflexion Diffuse (DRIFTS) de l’adsorption du monoxyde de carbone (CO) sur les différents sites d’une nanoparticule de platine. En conclusion, les catalyseurs préparés à partir de Pt0(η 2-C7H10)3 s’avèrent être plus actifs qu’EuroPt-1 pour la réaction d’oxydation du CO, ce qui démontre le potentiel d’utilisation des composés organométalliques dans le domaine de la catalyse hétérogène. / Organometallic chemistry resonates with homogeneous catalysis, and surface chemistry with heterogeneous catalysis. But the frontier between these two fields is very thin. In the 90’s, these fields approached each other and led to the development of a new science: organometallic surface chemistry, which underlines their complementarity. The goal of this science, with which this work is associated, is to create heterogeneous catalysts from organometallic compounds. Our goal is to contribute to the understanding of platinum nanoparticle formation - platinum being an important metal in heterogeneous catalysis - onto amorphous silica supports, thanks to organometallic chemistry. During this work, various Pt/SiO2 catalysts were prepared fromthree platinum precursors: the classical one, H2PtIVCl6.xH2O and two organometallic compounds PtII(η 4-C8H12)Cl2 et Pt0(η2-C7H10)3, and involved three supports: a commercial silica (Davison), a mesoporous silica SBA-15 synthesized in the laboratory, and a natural silica, the diatomite. Moreover, the study of the standard platinum reference catalyst “EuroPt-1” lead to the development of a methodology of operando Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) of carbon monoxide (CO) adsorption on the different sites of a platinum nanoparticle. Catalysts prepared from Pt0(η 2-C7H10)3 are more active than EuroPt-1 for the CO oxidation reaction, and this work shows the potential of organometallic precursors in the domain of heterogeneous catalysis.

In dieser Dissertation wird der Einfluss unterschiedlicher Sauerstoff-Koordinationsgeometrien um ein zentrales Kobaltatom evaluiert. Genauer werden Oxide, die tetraedrisch und oktaedrisch koordiniertes Kobalt enthalten, synthetisiert und charakterisiert. Zudem wird ihre Aktivität in Hinblick auf die Sauerstoffentwicklungsreaktion (OER) unter alkalischen Bedingungen untersucht. Die elektrochemischen Analysen zeigen dabei, dass Materialien, die Kobalt in tetraedrischer Sauerstoffkoordination enthalten, die besseren Katalysatorvorläufer für die OER sind. Weiterhin kann demonstriert werden, dass das Herauslösen von inaktiven Metallen aus einer Struktur die Aktivität erhöht. Darauf basierend wird das neue Material Zn0.35Co0.65O vorgeschlagen. Es kristallisiert in der Wurtzitstruktur und enthält nur tetraedrisch koordinierte Atome. In alkalischen Lösungen wandelt sich die Wurtzitstruktur über die Zwischenstufe Co(OH)2 zum gamma-Co(O)OH um, und nahezu alles Zink wird aus der Struktur herausgelöst. Dadurch wird ein Material mit einer großen elektrochemisch aktiven Oberfläche gewonnen, das unterkoordinierte CoO(6-x) Oktaeder als aktive Zentren für die OER enthält. Hierdurch wird eine herausragende katalytische Leistung erreicht. Um weitere Einblicke in die OER zu generieren, wird Diffuse Reflexions UV/Vis (DRUV) Spektroskopie verwendet. Es werden neuartige Durchflusszellendesigns vorgeschlagen, die es erlauben, DRUV Spektren während der Katalyse aufzunehmen, d.h. operando. Durch diesen spektroelektrochemischen Ansatz werden Veränderungen der Katalysatoren während der OER beobachtet. So kann die Phasenumwandlung von Zn0.35Co0.65O erfolgreich verfolgt werden. Ebenso kann gezeigt werden, dass CoAl2O4 und Co2SnO4 nur an ihrer Oberfläche katalytische Aktivität aufweisen. Durch den Vergleich mit ex situ Analysen werden eindeutige Struktur-Eigenschaftsbeziehungen vorgeschlagen und tiefere Einsichten in die katalytisch aktiven Strukturmotive erhalten. / In this PhD thesis, the influence of different coordination geometries of oxygen atoms around a central cobalt atom is evaluated. Specifically, oxides containing tetrahedral and octahedral coordinated cobalt are synthesized, characterized and their activity towards the OER under alkaline conditions is evaluated. The electrochemical analyses reveal, that materials containing cobalt in tetrahedral oxygen coordination are better precatalysts for the OER. Furthermore, it is demonstrated that leaching of inactive metals from a structure increases the activity as well. Based on the previous mentioned, the new material Zn0.35Co0.65O is proposed. It crystallizes in the wurtzite structure and contains solely tetrahedrally coordinated atoms. In alkaline solutions, it transforms from wurtzite structure via a hydroxide to gamma-Co(O)OH, and nearly all Zn is leached from the structure. By this, a material with a large electrochemically active surface area is generated, that contains under-coordinated CoO(6-x) octahedra as active centers for the OER. Thus, outstanding catalytic performance is achieved. To generate further insights into the OER, diffuse reflectance ultraviolet visible (DRUV) spectroscopy is facilitated. Novel flow-cell designs are proposed, that allow to record DRUV spectra of catalysts under working conditions, i.e. operando. By this spectroelectrochemical approach, changes the catalysts undergo during the OER are observed. The phase transitions of Zn0.35Co0.65O are successfully followed, and it can be further shown, that CoAl2O4 and Co2SnO4 are only active at their surface. By comparison to ex situ analyses, clear structure-activity correlations are proposed, and deeper insights in the catalytically active structural motifs are obtained.

A globalização da economia e dos negócios consolida um novo contexto de competição acirrada, de mercados mutantes, onde não é mais possível auscultar o passado para orientar as decisões do agora e muito menos do futuro. Com isso surgem as crises, os concorrentes mudam rapidamente sua forma de competir, surgem novos conceitos que são aplicados na gestão e organização dos negócios, novas tecnologias aparecem com ciclos de vida cada vez mais curtos, tornando obsoletas as que estão em uso. Nos setores empresariais mais afetados pelo novo ambiente, onde o acirramento da competição está mais presente e visível, parece estar sendo cada vez mais difícil para uma empresa sozinha enfrentar a concorrência. Surgem, então, alguns indícios de que as empresas estão buscando outras formas de gestão e de atuação para competir, que incluem inclusive a competição conjunta. Ou seja, uma forma de competição diferente entre as empresas, nas quais algumas se unem a outras empresas para disputar o mercado com outros agrupamentos e ou aglomerados de empresas. Esta união já foi evidenciada através de diferentes formatos supra-empresas. Dentre esses formatos destacam-se os clusters de negócios e as redes de negócios, nos quais a governança transcende as fronteiras de uma empresa isolada, atingindo a todo o aglomerado. A preocupação da presente pesquisa foi verificar se, dentro de agrupamentos de empresas denominados pela literatura como clusters, existem ou não, dentre as empresas nele instaladas, algumas que, também, se orientam por estratégias supraempresas de redes de negócios, e não só por estratégias de clusters. Isso foi verificado pela pesquisa, que, em dois clusters de negócios importantes para seus países, o do vinho do Porto, no Vale do Douro, em Portugal, e o de vinhos de mesa do Vale dos Vinhedos, na Serra Gaúcha, no Brasil, encontrou empresas orientadas por uma estratégia dual, isto é, por estratégia de cluster e por estratégia de rede de negócios. E esse achado é novo na literatura de entidades supra-empresas, até porque essas próprias entidades só recentemente tornaram-se conhecidas e objetos raras pesquisas. Foi, também, preocupação da pesquisa que embasou esta tese, verificar se o fato constatado de existirem empresas orientadas por estratégia dual contribuía ou não para um aumento em suas respectivas capacidades de competição, o que, também, acabou sendo comprovado. / The globalization of the economy and business consolidates a new context of fierce competition, changing markets, where you can no longer hear the past to guide the decisions of the now much less of the future. With that come the crisis, the competitors rapidly change its manner to compete, new concepts are applied in management and business organization, new technologies appears with lifecycles each time shorter, making obsolete the ones in use. In the business sectors most affected by the new environment, where increased competition is more present and visible, seems to be increasingly difficult for one company alone to face the competition. Then we see some evidence that companies are seeking other forms of management and performance to compete, including even the competition in conjunct. In other words, a form of competition of companies in which they join other companies to compete in the market with others agglomerates of companies. This union has been evidenced by different formats of supra-companies. Among these formats we can highlight the business clusters and business networks, in which governance transcends the boundaries of a single company, reaching the entire agglomerate. The concern of this study was to determine if, within groups of companies named in the literature as clusters, exist or not among the companies in it, some of them that are also guided by supra-companies strategies of networks business, not just by cluster strategies. This was verified by this research, two clusters of important business in their countries, the Port wine, in the Douro Valley, Portugal, and the wines of Vinhedos Valley, in Serra Gaúcha, Brazil, we found companies oriented with a dual strategy, in other words, by cluster strategy and business network strategy. And this discover is new in the literature of supra-companies entities, because those entities themselves are not of very recent scholarship. Another concern of this research was to verify if the fact of companies driven by a dual strategy had contributed to an increase in their competitiveness, what the study also confirmed