Resumen (Castellano) El aumento del consumo de energía global junto con las preocupaciones ambientales ha generado mucho interés por las fuentes de energía alternativas y limpias, como la energía solar fotovoltaica. Los investigadores en la comunidad fotovoltaica han estado buscando formas de reducir costos mientras mantienen o aumentan las eficiencias. Una mejor comprensión de los materiales implicados es esencial para el rápido desarrollo de nuevas tecnologías. Las películas delgadas I-III-VI2 ofrecen sistemas prometedores para lograr células solares de alta eficiencia a un costo menor. De hecho, al adaptar la composición de los compuestos, es posible cambiar la banda prohibida del material para captar la luz solar de manera más eficiente. Esta tesis se centra en la preparación y caracterización del material de la capa absorbente, especialmente las películas delgadas nanocristalinas y la consideración de las características estructurales y eléctricas de dicha capa principal absorbente de células. La tesis examina cómo las diferentes técnicas de preparación y uso del material podrían afectar las propiedades del películas delgadas sintetizadas. Películas delgadas CuInSe2 y CuInS2 se depositaron sobre sustratos de vidrio ITO usando la técnica de electrodeposición en solución acuosa. Las películas electrodepositadas se caracterizaron por difracción de rayos X (XRD), microscopía electrónica de barrido (SEM) y análisis de rayos X de energía dispersiva (EDS). Se investigaron los efectos de recocido sobre los precursores electrodepositados. La estructura de calcopirita de CuInSe2/CuInS2 mostró una mejora de la cristalinidad después del tratamiento posterior de selenización/sulfurización en atmósfera Se/S, respectivamente. Los estudios de XRD y SEM revelaron una mejora de la calidad cristalina de las películas de CIS después de los tratamientos térmicos. Las propiedades ópticas de las películas delgadas recocidas CuInSe2-Se y CuInSe2-S se han estudiado para determinar el efecto del proceso de recocido en diferentes ambientes de selenio y azufre. Además, modificamos el CuInxCryGa1-x-ySe2 de cobre indio, donde x = 0.4, y = (0.0, 0.1, 0.2, 0.3) la capa de superestrato por el proceso de recubrimiento por centrifugado. CuInxCryGa1-xySe2 donde x = 0.4, y = (0.0, 0.1, 0.2, 0.3) nanopartículas han sido sintetizadas en primer lugar usando un método hidrotermal químico húmedo que se basa en un proceso térmico sin vacío sin ningún proceso de selenización adicional. Introduciendo diferentes fuentes de metal en un autoclave con etilenamina como solvente, se obtuvieron nanopartículas de CIGS a diferentes temperaturas en un rango de 190-230 °C. Los resultados de la difracción de rayos X (XRD) confirmaron la formación de una estructura de calcopirita CuInxCryGa1-x-ySe2 tetragonal. Finalmente, se estudió el efecto de la temperatura de recocido en los materiales tipo Kesterita (como el Cu2ZnSnS4) que son materiales de muy bajo costo y que no dañan el medio ambiente. Estudiamos el crecimiento de las películas delgadas cuaternarias Cu2ZnSnS4 (CZTS) de kesterita mediante un depósito electroquímico de un solo paso seguido de un recocido a baja temperatura. La influencia de diferentes atmósferas de recocido a tiempos de recocido constantes (t = 45 min) y parámetros de control de preparación fijos; es decir, concentración de la solución de materiales de partida (sales de metales precursores), tiempo de deposición y potencial de electrodeposición. Se estudiaron las propiedades estructurales, de composición, morfológicas y ópticas, así como las propiedades fotoelectroquímicas. / Abstract Increasing global energy consumption together with environmental concerns has led to much interest in alternative, cleaner sources of energy such as solar photovoltaic. Researchers in the solar cell community have been looking for ways to reduce costs while maintaining or increasing already high efficiencies. A fundamental understanding of the materials under consideration is essential to rapid development of new technologies. The I-III-VI2 thin films offer promising systems for achieving high efficiency solar cells at lower costs. In fact, by tailoring the chemistry of the compounds it is possible to change the bandgap of the material in order to collect sunlight more efficiently. First of all, this thesis focuses on absorber layer material preparation and characterization, especially nanocrystalline thin films and consideration of both structural and electrical characteristics of such main cell absorber layer.The thesis examines how different preparation techniques and material usage could affect the properties of the synthesized thin films (absorber layer). In this study CuInSe2 and CuInS2 thin films were deposited onto ITO glass substrate using the electrodeposition technique in aqueous solution. The electrodeposited films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDS). The annealing effects on the electrodeposited precursors were investigated. The chalcopyrite structure of CuInSe2/CuInS2 showed an enhancement of crystallinity after subsequent selenization/sulfurization treatment in Se/S atmosphere, respectively. XRD and SEM studies revealed a dramatic improvement of the crystalline quality of CIS films after annealing treatments. The optical properties of annealed CuInSe2-Se and CuInSe2-S thin films have been studied in order to determine the effect of annealing process in different selenium and sulfur atmosphere. In the second step we modified copper indium CuInxCryGa1-x-ySe2 where x=0.4, y= (0.0, 0.1, 0.2, 0.3)superstrate layer by spin coating process. CuInxCryGa1-x-ySe2 where x=0.4, y= (0.0, 0.1, 0.2, 0.3) nanoparticles have been synthesized firstly using a wet chemical hydrothermal method that is based on a non-vacuum thermal process without any additional selenization process. Introducing different metal sources in an autoclave with ethylenediamine as solvent, CIGS nanoparticles were obtained at different temperatures range 190-230°C. The X-ray diffraction (XRD) results confirmed the formation of a tetragonal CuInxCryGa1-x-ySe2 chalcopyrite structure. Finally, we turned again to the study of the annealing temperature effect onKesterite materials but this time in those of very low-cost materials and environmentally friendly Cu2ZnSnS4. We studied the growth of quaternary Cu2ZnSnS4 (CZTS) kesterite thin films by a single step electrochemical deposition followed by annealing at low temperature. The influence of different annealing atmospheres at constant annealing times (t = 45 min) and fixed preparation controlling parameters; i.e., starting materials (precursor metal salts) solution concentration, time of deposition and electrodeposition potential. Structural, compositional, morphological, and optical properties, as well as photoelectrochemical properties were studied. / Resum (Valencià) L'augment del consum d'energia global juntament amb les preocupacions ambientals ha generat molt d'interès per les fonts d'energia alternatives i netes, com ara l'energia solar fotovoltaica. Els investigadors de la comunitat fotovoltaica han estat buscant formes de reduir costos mentre mantenen o augmenten les eficiències. Una millor comprensió dels materials implicats és essencial per al ràpid desenvolupament de noves tecnologies. Les pel·lícules primes I-III-VI2 ofereixen sistemes prometedors per aconseguir cèl·lules solars d'alta eficiència a un cost menor. De fet, en adaptar la composició dels compostos, és possible canviar la banda prohibida del material per captar la llum solar de manera més eficient. Aquesta tesi se centra en la preparació i caracterització del material de la capa absorbent, especialment les pel·lícules primes nanocristal·lines i la consideració de les característiques estructurals i elèctriques d'aquesta capa principal absorbent de cèl·lules. La tesi examina com les diferents tècniques de preparació i ús del material podrien afectar les propietats del pel·lícules primes sintetitzades. Pel·lícules primes CuInSe2 i CuInS2 es van dipositar sobre substrats de vidre ITO usant la tècnica d'electrodeposició en solució aquosa. Les pel·lícules electrodepositadas es van caracteritzar per difracció de raigs X (XRD), microscòpia electrònica de rastreig (SEM) i anàlisi de raigs X d'energia dispersiva (EDS). Es van investigar els efectes de recuit sobre els precursors electrodepositados. L'estructura de calcopirita de CuInSe2/CuInS2 va mostrar una millora de la cristal·linitat després del tractament posterior de selenització/sulfurització en atmosfera de Se o S, respectivament. Els estudis de XRD i SEM van revelar una millora de la qualitat cristal·lina de les pel·lícules de CIS després dels tractaments tèrmics. Les propietats òptiques de les pel·lícules primes recuites CuInSe2-Es i CuInSe2-S s'han estudiat per determinar l'efecte del procés de recuit en diferents ambients de seleni i sofre. A més, modifiquem el CuInxCryGa1-x-ySe2 de coure indi, on x = 0.4, i = (0.0, 0.1, 0.2, 0.3) la capa d'superstrat pel procés de recobriment per centrifugat. CuInxCryGa1-x-ySe2 on x = 0.4, i = (0.0, 0.1, 0.2, 0.3) nanopartícules han estat sintetitzades en primer lloc fent servir un mètode hidrotermal químic humit que es basa en un procés tèrmic sense buit sense cap procés de selenización addicional. Introduint diferents fonts de metall en un autoclau amb etilenamina com solvent, es van obtenir nanopartícules de CIGS a diferents temperatures en un rang de 190- 230 °C. Els resultats de la difracció de raigs X (XRD) van confirmar la formació d'una estructura de calcopirita CuInxCryGa1-x-ySe2 tetragonal. Finalment, es va estudiar l'efecte de la temperatura de recuit en els materials tipus kesterita (com el Cu2ZnSnS4) que són materials de molt baix cost i que no danyen el medi ambient. Vam estudiar el creixement de les pel·lícules primes quaternàries Cu2ZnSnS4 (CZTS) de kesterita mitjançant un dipòsit electroquímic d'un sol pas seguit d'un recuit a baixa temperatura. La influència de diferents atmosferes de recuit a temps de recuit constants (t = 45 min) i paràmetres de control de preparació fixos; és a dir, concentració de la solució de materials de partida (sals de metalls precursors), temps de deposició i potencial d'electrodeposició. Es van estudiar les propietats estructurals, de composició, morfològiques i òptiques, així com les propietats fotoelectroquímiques / Kamal Abdelhamied Saber, S. (2018). Synthesis and characterization of some nano-selenides and their applications in solar cells [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/107389

Настоящая работа состоит из 3 глав, заключения и списка используемых источников. Работа посвящена разработке способа селективного вольтамперометрического определения хлорамфеникола с использованием производных карбазола в качестве агентов молекулярного распознавания. Обоснована актуальность детектирования хлорамфеникола – антибиотика водного экотоксиканта. Рассмотрена альтернатива биологическим рецепторам оригинальными органическими молекулами для электрохимических и флуорометрических методов детектирования хлорамфеникола, а также подходы к электроосаждению рецепторного слоя. В работе изучена возможность применения оригинальной органической молекулы производного карбазола для определения хлорамфеникола. Приведены аналитические характеристики разработанного селективного способа определения хлорамфеникола. / This work consists of 3 chapters, a conclusion and a list of sources used. The work is devoted to the development of a method for selective voltammetric determination of chloramphenicol using carbazole derivatives as molecular recognition agents. The urgency of detecting chloramphenicol, an antibiotic of an aquatic ecotoxicant, is substantiated. An alternative to biological receptors with original organic molecules for electrochemical and fluorometric methods for detecting chloramphenicol, as well as approaches to electrodeposition of the receptor layer, are considered. The possibility of using an original organic molecule of a carbazole derivative for the determination of chloramphenicol has been studied. The analytical characteristics of the developed selective method for the determination of chloramphenicol are given.

Les travaux présentés dans ce mémoire ont pour but de mieux comprendre les relations entre la microstructure des revêtements métalliques nanocristallisés et leurs propriétés électrochimiques et mécaniques. Les dépôts de nickel sont élaborés par électrodéposition en courant continu et en courant pulsé dans un bain au sulfamate de nickel avec des sels de haute pureté, sans additif afin de minimiser les risques de contamination. Une caractérisation précise des états métallurgiques développés est réalisée au moyen de diverses techniques (MEB, MET, DRX, AFM, EBSD, SIMS, GDOES) afin d’évaluer la microstructure à différentes échelles (taille de grain, texture, contraintes internes, type de joints de grains) et d’identifier les contaminants. Trois types de texture ont été développés, associés à différentes tailles d’hétérogénéités structurales allant du micromètre à quelques dizaines de nanomètres. Une loi dite “d’échelle” a été mise en évidence, permettant de corréler les résultats obtenus par les diverses méthodes d’analyse. L’affinement de la taille de grain se traduit par une augmentation de la contamination dans les dépôts et entraîne une augmentation de la microdureté. La loi de Hall-Petch est influencée par l’orientation cristallographique ce qui a pu être relié à la nature des joints de grains et à la contamination des revêtements. Une étude préliminaire de la réactivité électrochimique en milieu acide a montré le rôle marqué des effets de surface (contamination et rugosité de surface). La réalisation d’un polissage électrolytique sur les revêtements a permis d’étudier l’influence des paramètres métallurgiques (taille de grain, contamination, nature des joints de grains) sur la réactivité. Les courbes de polarisation dans le domaine anodique et dans le domaine cathodique ont été simulées à l’aide de modèles cinétiques. Les résultats obtenus suggèrent que les joints de grains ont un effet qui peut être activant ou désactivant suivant l’étape considérée, ces effets pouvant être atténués par la présence d’impuretés. Les modifications de propriétés mécaniques et électrochimiques des revêtements ne peuvent être attribuées à une diminution de la taille de grain seule. / The purpose of the work presented in this manuscript is to better understand the relations between the microstructure of nanocrystallized metal coatings and their electrochemical and mechanical properties. Nickel deposits are elaborated by electrodeposition using direct current and pulse current in a nickel sulphamate bath with salts of high purity and without additive, in order to minimize the risks of contamination. A precise characterization of the developed metallurgical states is carried out by means of various techniques (SEM, TEM, XRD, AFM, EBSD, SIMS, GDOES) in order to evaluate the microstructure on various scales (grain sizes, textures, internal stresses, type of grain boundaries) and to identify contaminants. Three types of texture were developed associated with various sizes of structural heterogeneities from about one micrometer to a few dozens of nanometers. A “scale” law, allowing to correlating the results obtained by the various methods of analysis was shown. The grain size refinement results in an increase of contamination in the deposits and involves an increase of microhardness. The Hall-Petch law is influenced by the crystallographic orientation which could be connected to the nature of grain boundaries and the contamination of the coatings. A preliminary study of the electrochemical reactivity in acidic media showed the marked role of the surface effects (contamination and roughness of surface). Electrolytic polishing of the coatings highlights the influence of the metallurgical parameters (grain size, contamination, nature of grains boundaries) on the reactivity. The polarization curves in anodic domain and cathodic domains were simulated using kinetic models. The obtained results suggest that grain boundaries can either activate or deactivate the electrochemical kinetics according to the considered stage, these effects being able to be constrained by the presence of impurities. The modifications of mechanical and electrochemical properties of the coatings cannot be ascribed to a reduction of the grain size alone.

Made available in DSpace on 2017-07-20T12:40:17Z (GMT). No. of bitstreams: 1 Cleverson Santos.pdf: 2904178 bytes, checksum: 85140c2fc4cb486fe6c03e6a011296a3 (MD5) Previous issue date: 2016-05-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This thesis describes the preparation, characterization and application of electrochemical sensors and biosensors, using different modification techniques, based on Au as transducer. The enzymatic biosensor applied on the detection of pesticide carbaryl was built on a gold electrode functionalized with a monolayer of polyamidoamine dendrimer of fourth generation with a cystamine core (PAMAM-G4) on which it was immobilized the acetylcholinesterase enzyme (AChE), with the aid of glutaraldehyde. After evaluate and determine the best conditions for immobilization of the AChE enzyme (glutaraldehyde concentration of 1% (v/v) and the concentration of enzyme units 496 U. mL-1) on the monolayer of PAMAM, the catalytic activity of the enzyme was evaluated by chronoamperometry in presence of enzymatic substrate AChI obtaining = 2.9 . −1 . The biosensor response for carbaryl detection was based on the inhibition of the enzymatic activity caused by the pesticide. It was verified that 5 min in the pesticide solution is sufficient to block the enzyme active sites. After determining the best conditions for the construction of the biosensor, it was applied for carbaryl detection in the concentration range from 1.0 to 9.0 mol. L-1. The detection and quantification limits were found to be 0.0108 mol. L-1 and 0.032 mol. L-1, respectively. In the second chapter, it is reported the development of an immunosensor applied to qualitative detection of antibodies (AB) T. cruzi. The sensor was built on gold electrode modified with the thiol 3-mercaptopropionic acid (MPA) and the antigens (AG) T. cruzi were covalently immobilized on this surface by the reaction with EDC and NHS. The influence of concentration and of immersion time in the AG solution were evaluated using the techniques of cyclic voltammetry and electrochemical impedance spectroscopy in presence of [Fe(CN)6]3-/4- and the results showed that the best conditions were immersion time of 15 minutes and AG concentration of 0.5 g. L-1.The possible sites of non-specific binding were blocked with bovine serum albumin (BSA). The immersion time in the solution (AB) was also evaluated and the results showed that 30 minutes are sufficient for all specific bonds sites were occupied by AB T. cruzi. Selectivity tests in the absence of AB, only in the serum sample, and in the presence of AB Toxoplasma were performed. The results demonstrated that the immunosensor is selective, since it presented charge transfer resistance (Rct) values in the presence of AB T. cruzi 70% higher than the Rct values in presence of possible interferences.Therefore, the immunosensor presents itself as an alternative to qualitative diagnosis of american trypanosomiasis. In the third chapter, it is reported the modification of carbon graphite electrodes (CG) obtained from dry batteries zinc/carbon with Au microparticles obtained by potentiostatic electrodeposition. The variables involved in the electrodeposition process, such as the gold salt concentration, time and deposition potential were evaluated and optimized using cyclic voltammetry technique in the presence of redox couple [Fe(CN)6]3-/4-. The best conditions for the Au deposition were electrodeposition time of 700 s, potential of +0.3 V and concentration of 10.0 mmol. L-1. In these conditions, Au spherical particles were obtained with an average size of 420 nm, which were homogeneously deposited on the surface of GC electrode and promoted the increase of the electroactive area (GC electrode showed an area of 0.12 cm2 and GC/Au electrode presented an area of 0.25 cm2). The GC/Au electrode was applied for the separation and quantification of dopamine and uric acid present in a mixture. The voltammetric results showed that the GC/Au sensor is selective, once the potential peak separation between the DA and UA species was 370 mV. The detection and quantification limits were found to be 1.86 mol. L-1 and 6.09 mol. L-1 for dopamine and uric acid 17.5 mol. L-1 and 58.5 mol. L-1, respectively. In the development of the three electrochemical devices gold electrodes were used. From the results obtained for the three developed electrochemical devices it can be concluded that high electric conductivity, chemical stability, biocompatibility, ability to miniaturization in the form of microstructures and ease of functionalization of Au electrodes make them suitable conductive matrixes for construction of electrochemical sensors and particularly biosensors. / Esta tese descreve a preparação, caracterização e aplicação de sensores e biossensores eletroquímicos, utilizando diferentes técnicas de modificação baseadas no Au como transdutor. O biossensor enzimático aplicado na detecção do pesticida carbaril foi construído sobre um eletrodo de ouro funcionalizado com uma monocamada do dendrímero poliamidoamina de quarta geração com núcleo de cistamina (PAMAMG4),sobre o qual foi imobilizada com o auxílio de glutaraldeído a enzima acetilcolinesterase (AChE).Após avaliar e determinar as melhores condições de imobilização da enzima AChE (concentração de GLUT 1% (v/v) e concentração de unidades enzimáticas 496 U. mL-1) sobre a monocamada de PAMAM,a atividade catalítica da enzima AChE imobilizada foi avaliada por cronoamperometria na presença do substrato enzimático (AChI) obtendo-se o = 2,9 . −1. A resposta do biossensor na detecção de carbaril foi baseada na inibição da atividade enzimática causada pelo pesticida. Foi constatado que 5 min de imersão na solução do pesticida foram suficientes para que os sítios ativos da enzima fossem bloqueados. Após determinar as melhores condições de construção do biossensor, este foi aplicado na detecção de carbaril na faixa de 1,0 a 9,0 mol. L-1. Os limites de detecção e quantificação encontrados foram de 0,0108 mol. L-1 e 0,032 mol. L-1, respectivamente. No segundo capítulo é relatado o desenvolvimento de um imunossensor aplicado na detecção qualitativa de anticorpos (AB) T. cruzi. O sensor foi construído sobre eletrodo de ouro modificado com o tiol ácido 3-mercaptopropiônico (MPA) e sobre esta superfície foram imobilizados covalentemente pela reação com EDC e NHS, os antígenos (AG) T. cruzi. A influência da concentração da solução de AG e do tempo de imersão nesta solução para a construção do imunossensor foram avaliadas utilizando as técnicas de voltametria cíclica e espectroscopia de impedância eletroquímica na presença de [Fe(CN)6]3-/4- e os resultados demonstraram que as melhores condições foram: tempo de 15 min e concentração de 0,5 g. L-1. Os possíveis sítios de ligações não específicas foram bloqueados com albumina de soro bovino (BSA). O tempo de imersão na solução de AB também foi avaliado. Os resultados mostraram que 30 min são suficientes para que todos os sítios de ligações específicos fossem ocupados pelos AB T. cruzi. Testes de seletividade na ausência de AB,apenas em amostra de soro e também na presença de AB de Toxoplasma foram realizados. Os resultados demonstraram que o imunossensor é seletivo, pois este apresentou valores de resistência de transferência de carga (Rct) na detecção de AB T. cruzi 70% maiores do que na detecção dos possíveis interferentes. Portanto, o imunossensor apresenta-se como uma alternativa no diagnóstico qualitativo de tripanossomíase americana. No terceiro capítulo é descrito a modificação de eletrodos de carbono grafite (CG) obtidos de pilhas secas de zinco/carbono com micropartículas de Au obtidas pela eletrodeposição potenciostática. As variáveis envolvidas no processo de eletrodeposição, tais como concentração do sal de ouro, potencial e tempo de deposição foram avaliadas e otimizadas utilizando a técnica de voltametria cíclica na presença do par redox [Fe(CN)6]3-/4-. As melhores condições foram: tempo de 700 s, potencial de +0,3 V e concentração de 10,0 mmol. L-1. Nestas condições, foram obtidas partículas de Au esféricas com tamanho médio de 420 nm, as quais se apresentaram homogeneamente dispersas sobre toda a superfície do eletrodo de CG e promoveram o aumento da área eletroativa, (o eletrodo CG apresentou uma área de 0,12 cm2 e o eletrodo CG/Au uma área 0,25 cm2). O desempenho do eletrodo CG/Au foi avaliado na separação e quantificação de dopamina e ácido úrico presentes em uma mistura. Os resultados voltamétricos demonstraram que o sensor CG/Au é seletivo, pois apresentou separação de potencial pico de 370 mV entre as duas espécies. Os limites de detecção e quantificação encontrados foram de 1,86 mol. L-1 e 6,09 mol. L-1 para dopamina, e 17,5 mol. L-1 e 58,5 mol. L-1 para ácido úrico, respectivamente. A partir dos resultados obtidos para os três dispositivos eletroquímicos desenvolvidos pode-se concluir que a elevada condutividade elétrica, estabilidade química, biocompatibilidade, possibilidade de miniaturização na forma de microestruturas e a facilidade de funcionalização dos eletrodos de Au fazem destes matrizes condutoras apropriadas para construção de sensores e particularmente biossensores eletroquímicos.

Actuellement, les supercondensateurs sont au centre de beaucoup de recherches. Ils offrent une solution potentielle pour le stockage réversible de l´énergie que ce soit pour le domaine spatial, aéronautique ou encore le transport (véhicules hybrides). Un axe de recherche important, visant à augmenter les densités d'énergie et de puissance, est consacré aux systèmes oxydes de métaux de transition /charbon actif (C) asymétriques. Les systèmes à base de RuO2 présentent les capacités les plus élevées, supérieures à 700 F/g, mais leur coût et leur toxicité limitent leur application aux petits appareils électroniques. Des oxydes moins coûteux tels que les oxydes de cobalt (notamment Co3O4), MnO2, V2O5, Fe3O4, NiO, Ni(OH)2, ainsi que des polymères conducteurs électroniques, ont été étudiés de manière approfondie au cours des dernières décennies jusqu’à être utilisés, pour certains, dans des dispositifs commerciaux. Mais aucun système n’a été aussi étudié que le C / MnO2. En effet, il a été démontré que ce dernier est particulièrement intéressant car il peut fonctionner dans des milieux aqueux à des tensions pouvant aller jusqu’à 2V tout en gardant une bonne stabilité électrochimique durant le vieillissement. Néanmoins, les performances du système, en particulier en termes de densité de puissance, sont limitées à cause de la mauvaise conductivité électronique du MnO2. Il est possible de surmonter ce problème en ajoutant à l’oxyde de manganèse, des matériaux conducteurs à base de carbone (noir de carbone, nanotubes de carbone…) ou encore, en développant des stratégies de greffage ou de décoration plus élaborées. La combinaison d’oxydes avec des espèces carbonées est très largement rapportée dans la littérature alors que le mélange d’oxydes de différente nature l’est beaucoup moins. Nous proposons dans ce projet de synthétiser et de développer des matériaux originaux améliorant, par un effet synergique, les propriétés intéressantes du manganèse, du cobalt et de l'oxyde / hydroxyde de nickel. Les inconvénients de chaque composant étant compensés par les bonnes propriétés complémentaires des autres. Nous cherchons à réunir en un seul matériau (ou composite), le bon comportement pseudocapacitif du manganèse, la bonne conductivité électronique associée aux oxydes de cobalt, la grande capacité de l'hydroxyde de nickel ainsi que les propriétés de conduction du carbone. Ce projet de doctorat vise à concevoir et à fabriquer de nouvelles classes d'électrodes composites hybrides basées sur des assemblages de graphène (pour la capacitance renforcée à double couche) et d'oxydes poreux de métaux de transition (pour une capacité faradique supplémentaire due à de multiples processus rédox réversibles). Les avantages combinés du graphène et des oxydes de métaux de transition permettront aux supercondensateurs à haute densité d'énergie de travailler dans des électrolytes aqueux respectueux de l'environnement ce qui est, aujourd’hui, un besoin reconnu. / Supercapacitors are the focus of much research at the present time. They offer a potential solution for reversible energy storage in the fields of space, aircrafts or transportation (hybrid vehicles). An important research line, aiming at increasing both energy and power densities, is devoted to asymmetric transition metal oxides / activated carbon (C) systems. RuO2-based devices exhibit the highest capacitance, more than 700 F/g, but their cost limits the applications to small electronic devices. Less expensive oxides such as cobalt oxides (especially Co3O4), MnO2, V2O5, Fe3O4, NiO, Ni(OH)2, as well as electrically conducting polymers, have been extensively studied in the past decades, or used in commercial devices; they EACH exhibit each drawbacks and advantages with regard to applications. But no system has been investigated as much as the C/MnO2 one, which is particularly interesting because it can work in aqueous media at tensions up to 2 V, and high stability in ageing has been demonstrated. Nevertheless, the performances of the system, especially in terms of power density, are limited by the poor electronic conductivity of MnO2. This problem is usually solved by simply mixing conductive carbon materials (carbon black, CNTs…) with MnO2 or by developing more elaborated grafting or decoration strategies. The combination of oxide and carbonaceous species is widely reported in the literature, whereas combining oxides with different natures is less frequently encountered. We propose in this project to synthesize and develop original materials enhancing, through a synergistic effect, the interesting properties of manganese, cobalt and nickel oxide/hydroxide, the drawbacks of each component being overbalanced by the good complementary properties of the other components. We aim at gathering in one single material (or composite), the good pseudocapacitive behavior of manganese, the good electronic conductivity associated to cobalt oxides, the high capacity of nickel hydroxide, as well as the enhanced conduction properties of carbon. The present PhD project aims at designing and manufacturing new classes of hybrid composite electrodes based on assemblies of graphene (for enhanced double layer capacitance) and porous transition metals oxides (for additional faradaic capacitance due to multiple reversible redox processes) directly applied on metallic current collectors. The combined advantages of graphene with those of transition metals oxides will enable supercapacitors with high energy density, working in environmentally friendly aqueous electrolytes, which are an acknowledged need. / A procura crescente de energia em setores distintos, como residencial, transporte e industrial, bem como a proliferação de fontes renováveis de produção de energia, exigem novos e mais eficientes dispositivos de armazenamento de energia. Consequentemente, tem-se observado um interesse crescente na produção e engenharia de materiais para armazenamento de energia. Muito dos esforços de R&D estão centrados no desenvolvimento de materiais nanoestruturados que possam responder aos requisitos da aplicação, tais como densidade de energia, densidade de potência e estabilidade face à ciclagem do dispositivo. Presentemente são muitos os materiais investigados como potenciais candidatos para elétrodos para dispositivos de armazenamento de energia por via eletroquímia, nomeadamente baterias, condensadores, pseudocondensadores ou supercondensadores. O objetivo do presente trabalho é produzir e estudar novos materiais com uma resposta eletroquímica intermédia entre um elétrodo típico de supercondensador e um elétrodo típico de bateria, também conhecidos como elétrodos híbridos. Por essa razão, selecionaram-se hidróxidos e óxidos de níquel e cobalto devido à sua elevada atividade eletroquímica e baixo custo. Estes materiais foram combinados com derivados de grafeno, que exibem alta condutividade e elevada área superficial ativa. Portanto, este trabalho foca a síntese e caracterização fisico química e eletroquímica de hidróxidos e óxidos de níquel-cobalto nanoestruturados e sua combinação com óxido de grafeno reduzido para aplicações de armazenamento de energia. A síntese foi efectuada por duas vias distintas: eletrodeposição e exfoliação. A eletrodeposição é usada para obter hidróxidos e óxidos de níquel-cobalto em combinação com óxido de grafeno reduzido. Os resultados evidenciam um efeito sinérgico quando o óxido de grafeno reduzido é combinado com o (hidr)óxido de níquel- cobalto, isto é, um aumento na capacidade, condutividade e estabilidade do compósito quando comparado com o (hidr)óxido de níquel-cobalto. Neste trabalho é dada especial atenção à espectroscopia de impedância eletroquímica que foi utilizada para avaliar os fenômenos que ocorrem durante a carga e descarga contínua e compreender os processos que ocorrem no material ativo e que resultam na sua degradação. O hidróxido de níquel-cobalto é também preparado por exfoliação, em meio aquoso, por meio da intercalação de lactato, enquanto o tetra-butilamónio é utilizado na exfoliação do óxido de níquel-cobalto. A resposta eletroquímica é avaliada em diferentes eletrólitos após reconstrução. Os resultados revelam a influência das espécies intercaladas durante o processo de exfoliação: quando a exfoliação é realizada para fins de armazenamento de energia, as espécies intercaladas e a força da interação com o material ativo devem ser consideradas de antemão para evitar o bloqueio superficial ou inibição da interação elétrodo-eletrólito. Os resultados mostraram que a exfoliação é uma rota promissora para aumentar a área de superfície ativa dos materiais, um parâmetro crítico no desempenho eletroquímico dos materiais dos eletrodos. Nesta dissertação é também estudado o mecanismo de carga-descarga do hidróxido de níquel-cobalto, que ainda não está completamente entendido. Assim, compreender esse mecanismo é um passo crítico para otimizar a morfologia e o desempenho do material e para projetar futuros dispositivos de armazenamento de energia. Para esclarecer os processos que ocorrem durante a carga, aplica-se o modelo de Mott-Schottky foi aplicado parade modo a avaliar a variação da conductividade do material e da sua capacidade na interface elétrodo-eletrólito. [...]

Les mécanismes d’électrodéposition réalisés à partir d'électrolytes à base de liquides ioniques ne sont pas très bien compris en raison de l’organisation structurale complexe de ces électrolytes. Dans cette thèse, nous étudions les relations qui existent entre la morphologie des films, les propriétés électrochimiques ainsi que la structure de l'électrolyte liquide ionique. Plusieurs solutions ont été étudiées: CuCl, CuCl2 et CuSO4 dans 1-éthyl-3-méthylimidazolium éthyl-sulfate [EMIM] [EtSO4]; AgTFSI, CuTFSI2 et AlTFSI3 en 1-éthyl-3-méthylimidazolium bis(trifluorométhylsulfonyl)imide [EMIM] [TFSI]. Des mesures de cyclovoltammétrie montrent que les réductions de l’argent et du cuivre sont quasi-réversibles et se produisent par une réaction de transfert mono-électronique {(Ag (I) → Ag (0), (Cu (II) → Cu (I)) et (Cu (I) → Cu (0)}. La réduction de l'aluminium est irréversible. Les coefficients de diffusion augmentent avec la température de l'électrolyte et sont également influencés par l'état d'oxydation du métal et des anions en solution. Des films minces métalliques ont été obtenus pour toutes les solutions, sauf pour AlTFSI3. L'analyse par XRD et EDX montrent que les films sont cristallins et sont principalement constitués de cuivre ou d'argent pur. Leur morphologie est contrôlée par la température, du temps et du potentiel d’électrodéposition. D'une manière générale, l'élévation du temps de dépôt et de la température augmente la couverture du film et de la taille des particules, tandis que l'augmentation du potentiel de dépôt diminue la taille des particules. La structure des électrolytes a été étudiée par Raman et IR spectroscopies et interprétée à l’aide de méthodes théoriques de chimie quantique. Pour AgTFSI-[EMIM][TFSI], le cation d’argent est solvaté par trois anions TFSI-. Pour CuCl2-[EMIM][EtSO4], le cation de cuivre est solvaté par deux anions de chlore et deux anions EtSO4. / Deposition mechanisms from ionic liquid-based electrolytes are not fully understood due to difficulties in probing the electrolyte structure. In this study, we investigate the links between films morphology, electrochemical properties of the electrolyte and electrolyte structure. Several solutions were investigated: CuCl, CuCl2 and CuSO4 in 1-ethyl-3-methylimidazolium ethylsulphate [EMIM][EtSO4]; AgTFSI, CuTFSI2 and AlTFSI3 in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [EMIM][TFSI]. Cyclic-voltammetry shows that silver and copper reductions are quasi-reversible and occur by one-electron transfer reaction {(Ag(I)→Ag(0), (Cu(II)→Cu(I)) and (Cu(I)→Cu(0)}. Aluminium reduction is irreversible. The diffusion coefficients increase with electrolyte temperature, and are also influenced by the metal oxidation state and anions in solution. Metallic thin films were obtained for all the solutions except AlTFSI3. XRD and EDX analysis show that the films are crystalline and consist mainly of pure copper or silver. Their morphology is controlled by the deposition temperature, time and potential. In general, increasing the deposition time and temperature increases the film coverage and particle size, whereas increasing the deposition potential decreases the particle size. The electrolytes structure was investigated by Raman and IR spectroscopies, supported by theoretical calculations. For the AgTFSI-[EMIM][TFSI], silver cation is solvated by three TFSI-. For the CuCl2-[EMIM][EtSO4], copper cation is solvated by two chlorines and two EtSO4-.

L’auto-assemblage de particules colloïdales est une technique polyvalente qui permet la fabrication de cristaux colloïdaux à de grandes échelles. Le but de notre étude est de développer des processus fiables et reproductibles pour fabriquer des matériaux photoniques et plasmoniques pouvant être incorporés au sein de différents dispositifs.Des opales inverses en dioxyde de titane composées d’un nombre précis de couches ont été intégrées au sein de cellules solaires à colorant «tout solide», ce qui a entraîné une amélioration des performances allant jusqu'à105%. Des surfaces d'ornano structurées présentant une absorption omnidirectionnelle et totale de la lumière ont été fabriquées par dépôt électrolytique d'or à travers une monocouche de particules de polystyrène. En outre, des surfaces d'or très rugueuses présentant des propriétés anti-réfléchissantes ont également été élaborées. En modulant la taille des interstices entre les particules de polystyrène, il a été possible de fabriquer par électrodéposition séquentielle des nanopiliers d’or de différentes longueurs. Enfin, l'utilisation d'une monocouche non compacte de particules comme moule a permis la réalisation de métamatériaux de type fishnet / The bottom-up self-assembly of colloidal particles is a versatile technique that allows the fabrication of large areas of colloidal crystals. The purpose of the present study is to develop highly reliable and reproducible process routes to fabricate nanostructured photonic and plasmonic materials that can be incorporated into different devices. Titania inverse opals with precise control of the layer thickness have been successfully incorporated into solid state DSSCs which showed improved performance of up to 105 %. Nanostructured gold surfaces that exhibited omnidirectional total light absorption have been fabricated by controlled electrodeposition of gold through colloidal monolayers of polystyrenebeads. In addition, very rough gold surfaces that showed anti-reflective properties were also made. By tuning the pore size of the colloidal monolayer, plasmonic gold nanopillarswith different lengths were fabricated by a sequential electrodeposition process. Using a non close-packed monolayer of PS beadscombined with electrodeposition,fishnet metamaterialswere fabricated.

Dans un contexte d'integration des dispositifs de conversion d'energie de petite puissance, le travail de these presente porte sur la realisation de micro-bobines integrees sur silicium. Les contraintes liees a ce type d'integration resident dans la mise au point, la compatibilite des procedes technologiques contribuant a la fabrication du systeme complet et le cout de fabrication. Dans un premier temps, une etude bibliographique nous a permis de faire une synthese sur les structures integrables de micro-bobines ainsi que sur les materiaux conducteurs et magnetiques et leurs techniques de depot. Une fois les objectifs fixes, notamment concernant la nature des materiaux a deposer, nous avons mis au point les depots electrochimiques et les procedes photolithographiques de resines epaisses destinees a la realisation de moules. Ces resines doivent resister a la fois a des contraintes chimiques et physiques fortes. Une premiere structure de micro-bobine de type spirale a ete dimensionnee et le processus de fabrication a ete identifie. En parallele, des motifs specifiques de forme bien definie ont ete etudies puis realises afin de caracteriser les couches deposees par electrochimie, en termes de resistivite, permeabilite et composition de l'alliage. La derniere partie de la these a consiste a appliquer ce procede de fabrication a une seconde structure de bobine dont la geometrie a ete definie dans le but de reduire le nombre d'etapes technologiques. Actuellement les premiers prototypes de ces bobines ont ete realises avec de faibles epaisseurs de materiaux. Ceci nous a permis de valider les procedes de fabrication de ces dispositifs.

<p>This thesis deals with the engineering of novel nanomaterials, particularly nanocomposites and nanostructured surfaces with enhanced functionalities. The study includes two parts; in the first part, an in situ sol-gel polymerization approach is used for the synthesis of polymer-inorganic hybrid material and its exceptional transparent UV-shielding effect has been investigated. In the second part, electrodeposition process has been adapted to engineer surfaces and the boiling performance of the fabricated nanostructured surfaces is evaluated.</p><p>In the first part of the work, polymer-inorganic hybrid materials composed of poly(methylmethacrylate) (PMMA) and zinc compounds were prepared by in situ sol-gel transition polymerization of zinc complex in PMMA matrix. The immiscibility of heterophase of solid organic and inorganic constituents was significantly resolved by an in situ sol-gel transition polymerization of ZnO nanofillers within PMMA in the presence of dual functional agent, monoethanolamine, which provided strong secondary interfacial interactions for both complexing and crosslinking of constituents.</p><p>In the second part of the work, nanoengineering on the surface of copper plates has been performed in order to enhance the boiling heat transfer coefficient. Micro-porous surfaces with dendritic network of copper nanoparticles have been obtained by electrodeposition with dynamic templates. To further alter the grain size of the dendritic branches, the nanostructured surfaces underwent a high temperature annealing treatment.</p><p>Comprehensive characterization methods of the polymer-inorganic hybrid materials and nanoengineered surfaces have been undertaken. XRD, 1H NMR, FT-IR, TGA, DSC, UV-Vis, ED, SEM, TEM and HRTEM have been used for basic physical properties. Pool boiling tests were performed to evaluate the boiling performance of the electrodeposited nanostructured micro-porous structures.</p><p>The homogeneous PZHM exhibited enhanced UV-shielding effects in the entire UV range even at very low ZnO content of 0.02 wt%. Moreover, the relationship between band gap and particle size of incorporated ZnO by sol-gel process was in good agreement with the results calculated from the effective mass model between bandgap and particle size. The fabricated enhanced surface has shown an excellent performance in nucleate boiling. At heat flux of 1 W/cm2, the heat transfer coefficient is enhanced over 15 times compared to a plain reference surface. A model has been presented to explain the enhancement based on the structure characteristics.</p>

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