Tesi sul tema "Catalyseurs électrochimiques"
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Hadjar, Abdelkader. "Catalyseurs électrochimiques pour le stockage et la réduction des oxydes d'azote (NOx)". Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10111.
The main objective of this study was to demonstrate the coupling between NOx storage/reduction process on barium, with an electrochemical reduction of NOx (micro fuel cell effect) on the same catalyst. The micro fuel cell effect is ensured by a an electromotive force (potential) which is created between catalytic nanoparticules (Pt and Rh) in contact with an ionic conductor (YSZ) and an electronic conductor (doped SiC). The micro fuel cell effect was observed, during the regeneration phase of the catalysts (rich period), on a Pt/Ba/doped α-SiC-YSZ/Rh monolithic system under lean-burn gasoline conditions at 400°C with an enhancement of about 10 % of the NOx conversion over a complete cycle lean/rich. This electrochemical effect was characterized by the electrochemical oxidation of CO (produced by steam reforming) into CO2 by using O2- ions coming from YSZ. Under Diesel conditions, the micro fuel cell system was found to work at low temperature especially at 300°C. In the second part of the work, a new generation of NOx Storage and reduction catalyst was developed consisting only of noble metals (Pt and/or Rh) deposited on YSZ support (Ba free catalyst). The catalytic measurements revealed that YSZ can be used as a NOx storage material in lean burn conditions (Gasoline and Diesel) especially when it was previously reduced under hydrogen. The storage mechanism would take place on the oxygen vacancies created by the removal of O-2 ions from the YSZ structure
Jabbour, Darine. "Influence de la composition et de la structure des hétéropolyanions sur leurs propriétés électrochimiques et électrocatalytiques". Paris 11, 2005. http://www.theses.fr/2005PA112209.
The aim of this work was to study the effects of the accumulation of nickel and copper centres in heteropolyanions on their electrocatalytic behaviour. As concerns Ni-containing heteropolyanions, several compounds based on the trivacant [B,α-PW9O34]9- with different Ni nuclearities were selected. Their stability and redox behaviour in aqueous media were evaluated by UV/vis spectroscopy and cyclic voltammetry as a function of pH with the aim to find conditions under which these compounds could be suitable candidates for electrocatalytic processes. Detailed electrochemical studies on the behaviour of Cu-substituted species were carried out, and particularly on the behaviours of Cu-centres. Also, particular attention was devoted to the electrochemical studies undertaken on the wheel-shaped [Cu20Cl(OH)24(H2O)12(P8W48O1 84)]25-. We demonstrate that an increase in the number of copper centres within this polyanion has beneficial effects on the electrocatalytic reduction of nitrate and nitrite. We have succeeded in isolating several pure samples of α1-P2W17M complexes, (M = MnII, CoII, NiII, CuII, ZnII) by a simple method where preparation and isolation of the lacunary α1-K9LiP2W17O61. 18H2O from K12[H2P2W12O48]. 24H2O were not explicitly necessary steps
Fournier, Maxime. "Etudes électrochimiques de la catalyse de production de dihydrogène par des complexes glyoximes de cobalt". Paris 7, 2012. http://www.theses.fr/2012PA077256.
At present, platinum catalyst are used for the proton reduction in fuel cells. The challenge is now to replace the expensive and limited platinum metal by non-noble metal complexes. Several groups have already proposed coordination metal complexes for the electrocatalysis of hydrogen production. Among those complexes, the glyoxime cobalt: tris-cobaloxime and bis-cobaloxime complexes are reputed to be efficient molecular catalyst. This study using cyclic voltammetry and preparative electrolysis coupled to gas chromatography (GC) reveals a deactivation process of those catalysts in presence of strong acid. Characterization by D. R. X and S. E. M / E. D. X of the carbon electrode reveals an electrodeposition process of cobalt nanoparticles on the surface. These nanoparticles are remarkably active catalysts for H2 production in organic solvent with acid or in water at pH 7 at low overpotential. Thèse nonnoble metal complexes previously described as pure homogeneous catalysts are in fact precursors of an effective heterogeneous catalyst
Tainon, Yannick. "Etude par méthodes électrochimiques et spectroscopiques "in situ" de catalyseurs au platine partiellement désactives par adsorption de composés soufres". Poitiers, 1988. http://www.theses.fr/1988POIT2265.
Kilaparthi, Sravan Kumar. "Carbon-based electrocatalysts for CO2 reduction, PET hydrolysate, and water splitting towards value-added products". Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILN051.
This study tackles the major global challenges such as CO2 emissions, energy crisis and PET plastic waste mismanagement, which not only pollutes the environment but also contributes to CO2 emissions during incineration. The innovative approach presented in this thesis offers a dual solution, addressing both PET waste and CO2 emissions simultaneously.Two remarkable systems have been explored in this thesis. The first utilized Bismuth oxide carbonate (BOC) functionalized reduced graphene oxide (rGO) for cathodic CO2 electroreduction (CO2RR), while CuCoO on rGO was employed for anodic PET hydrolysate oxidation. Impressively, the anodic CuCoO@rGO catalyst displayed exceptional electro-activity, achieving an outstanding Faradaic efficiency (FE) of 85.7% at 1.5V vs. RHE. Simultaneously, the cathodic BOC@rGO catalyst demonstrated an impressive FE of 97.4% at -0.8 V vs. RHE, facilitating the production of formate from CO2RR. When integrated into an electrolyzer setup, this approach resulted in formic acid production at a low cell voltage of 1.9 V and a remarkable formate FE of 151.8% at 10 mA cm-2.Another system employed a 3D activated carbon felt (aCF) electrode as substrate and Bismuth has been deposited electrochemically on the CF (Bi@aCF) which acts as the cathode CO2RR and nickel cobalt phosphate-deposited carbon felt (NiCoPOx@CF) for the anodic PET hydrolysate oxidation process. This setup achieved a high FE of 94% during CO2RR at -0.8 V vs. RHE, producing formate, and a FE of 95% for anodic PET hydrolysate oxidation to formate at a low potential of 1.5 V vs. RHE. Remarkably, the two-electrode electrolyzer attained an extraordinary FE of 157% to produce formate at a cell voltage of 1.8 V. This breakthrough represents a novel pathway for upcycling PET waste, reducing CO2 emissions, and promoting environmental sustainability.Additionally, our experiments also delved into water electrolysis, where a novel strategy involving Ru embedded in a carbon nitride matrix was proposed. This approach, utilizing a covalent organic framework 2D CIN-1 structure with coordinated Ru+2, resulted in Ru oxide nanoparticles with low-valence Ru sites arranged in nanowires between layers of graphitic carbon nitride after pyrolysis. This material exhibited significantly lower overpotentials for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) compared to benchmark Pt and RuO2 catalysts, demonstrating remarkable catalytic stability. This discovery holds tremendous promise for advancing the field of water splitting and contributing to the development of sustainable energy solutions
Gueret, Robin. "Systèmes moléculaires pour la production d'hydrogène photo-induite dans l'eau associant des catalyseurs de cobalt à un photosensibilisateur de ruthénium ou un colorant organique". Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAV074/document.
The work of this manuscript is focused on the design of molecular systems in homogeneous solution for photocatalytic production of molecular hydrogen in water using cobalt catalysts with pentadentate tetrapyridinic and tetra- and pentaza macrocyclic ligands. In association with [Ru(bpy)3]2+ as photosensitizer and sodium ascorbate as sacrificial electron donor, the macrocycle based catalysts display high performances for H2 production, far exceeding those of the polypyridine based catalysts, both in terms of activity and stability, because of the stability of their reduced state «Co(I)». Finally, [Ru(bpy)3]2+ was successfully substituted with a robust organic dye belonging to the triazatriangulenium family, leading to an even more efficient photocatalytic system. These results demonstrate well that organic dyes are a truly efficient alternative to noble metal based photosensitizers, even in acidic aqueous medium
Vanhoye, Didier. "Génération électrochimique de catalyseurs : application aux réactions de carbonylation". Lille 1, 1987. http://www.theses.fr/1987LIL10128.
Aboulkassim, Aicha. "Electrosynthèse d'homopolymères et de copolymères (phenylène-carbazolylène) : propriétés des poudres et des films". Paris 13, 1991. http://www.theses.fr/1991PA132006.
Brusson, Jean-Michel. "Génération électrochimique de catalyseurs Ziegler-Natta pour la polymérisation de l'éthylène". Lille 1, 1988. http://www.theses.fr/1988LIL10125.
Srour, Mahmoud. "Etude électrochimique de catalyseurs à base de platine utilisables en pile à combustible". Grenoble INPG, 1999. http://www.theses.fr/1999INPG0047.
Canioni, Romain. "Approche moléculaire de la synthèse et de la réactivité de catalyseurs à base de polyoxométallates : applications à l'oxydation d'alcanes légers par l'oxygène moléculaire". Versailles-St Quentin en Yvelines, 2010. http://www.theses.fr/2010VERS0042.
Research on new selective oxidation catalysts with mixed valence led to the isolation of two families of Keggin-type polyoxoanions reduced and bicapped: {XMo12Sb2O40} and {XMo8V4Te2O40} (X = P, Si, Ge, As). Their characterization revealed noticeable magnetic and electrochemical properties. An interesting activity in isobutane oxidation has been obtained for doped catalysts with [PMo12Sb2O40]3-. The mixed-oxide crystalline phase Mo-V-Te (M1 phase) active in oxidative dehydrogenation of ethane has been realized by one pot synthesis using a molecular precursor, [Te5Mo15O57]8-, formed by the hydrolysis of the Keplerate ion {Mo132} by tellurite ions. In addition, two hybrid mesoporous solids (MOF) have been investigated as innovative supports for polyoxometalates: chromium(III) terephtalate MIL-101(Cr), allowing direct filling of POM via ionic exchange, and iron(III) trimesate MIL-100(Fe), allowing encapsulation by formation of the material in presence of POM
Rousseau, Séverine. "Développement de catalyseurs plurimétalliques multifonctionnels pour l'oxydation électrocatalytique de l'éthanol dans une pile à oxydation directe (DEFC)". Poitiers, 2004. http://www.theses.fr/2004POIT2301.
New technology solutions are required to deal with the global warming, in relation with power consumption but also with the limitations of crude oil reserves. Fuel cells are an electrochemical device that can play a significant role in this strategy. Ethanol is a promising candidate due to its availability, its low toxicity and its high specific energy. Ethanol can be directly used as an anodic fuel for proton exchange membrane fuel cells (PEMFC). However its dissociative adsorption on platinum sites leads to the formation of poisoning species responsible for the low activity of the catalysts. This study reports the preparation of platinum-based multimetallic systems by the colloidal route. Electrochemical measurements have shown a decrease of the anodic overpotential of 200 mV with Vulcan XC-72 supported Pt-Sn and Pt-Sn-Ru catalysts. Infrared reflectance spectroscopy studies in addition to chromatographic analysis of the reaction products have demonstrated that the reaction mechanism is different with Pt and Pt-Sn catalysts. The Pt-Sn catalyst with a (90:10) atomic composition and a 60 wt. % metal loading appears to be the most active system. Fuel cell experiments have reported a power density of 62 mW cm-2 at 110ʿC. Anodes with a geometric area of 25 cm2 have been prepared, exhibiting a high activity and stability in fuel cell relevant conditions
Gorgy, Karine. "Etude électrochimique de deux catalyseurs d'oxydation : les N-hydroxyphtalimides et les complexes binucléaires oxo de fer (III)". Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10258.
Henrotte, Olivier. "Méthode pour l’analyse de l’activité de la réduction de l’oxygène de catalyseurs sans métaux nobles par microscopie électrochimique". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS473.
The decrease of fuel cells cost is necessary to provide a worldwide access to the technology. Synthesis of noble metal-free catalysts is a promising way to achieve this goal. The electrochemical analysis of these materials is however not easy either to compare the electrocatalytic properties or to understand the performances of these catalysts. The scientific community generally studies catalysts at a macroscale, where the recorded response is averaged on a very large number of catalytic objects. The works presented here shows the setup of a method to analyze the electrocatalytic activity of noble metal-free catalyst for the oxygen reduction reaction in acidic media by scanning electrochemical microscopy. This method brings several advantages such as the possibility to study and compare multiple catalysts on the same sample at a macro- or a microscale. The comparison of several catalysts with this setup is then. A catalyst has been studied under various conditions of: loading, surface area, weight of catalyst and quantity of additives such as Nafion. The investigation of the material stability is also illustrated. These results suggest large range of application of the technique and many possibilities in the future are now open to investigated noble metal-free electrocatalytic materials
Cojocariu, Ana Mihaela. "Matériaux mésostructurés pour des applications dans les oxydations catalytiques : optimisation de la synthèse et des performances catalytiques". Electronic Thesis or Diss., Montpellier 2, 2010. http://www.theses.fr/2010MON20030.
The objective of this thesis was the optimization of the synthesis and catalytic performances of Ti-containing materials in the oxidation with H2O2 of a wide range of model organic compounds. The original part is represented by the synthesis of SiO2-TiO2 mixed oxides by a non hydrolytic sol-gel procedure and their use in different catalytic reactions like: sulfoxidation, epoxidation of olefins, oxidation of aromatic hydrocarbons and phenols. These materials were compared with ordered mesoporous materials (Ti-MCM-41 and Ti-MCM-48) and microporous titanosilicalite TS-1. The non-hydrolytic sol-gel process based on the etherolysis and condensation of chloride precursors offers a simple one-step route to mesoporous SiO2-TiO2 xerogels with a good dispersion of Ti species and outstanding textural properties, without resorting to supercritical drying procedures as in the case of the mixed oxides obtained by a hydrolytic way. Moreover, these materials exhibited a remarkable catalytic activity in the oxidation with H2O2 of all the organic compounds investigated (significant conversions, good selectivities and H2O2 efficiencies). The catalysts were stable under operating conditions
Kerangueven, Gwénaëlle. "Compréhension du mécanisme d'oxydation électrochimique du diméthoxyméthane (DMM) en vue de son application en pile combustible". Poitiers, 2007. http://www.theses.fr/2007POIT2284.
The DMM electrooxydation has been studied on polycrystalline and single crystals platinum and carbon-supported Pt-based nanosized electrocatalysts. FTIR in situ experiments have been led in the goal to identify adsorbed species and reaction products of DMM adsorption and oxidation at different potentials. At low sweep rate and high DMM concentration the DMM electrooxidation is partially deactivated. This phenomenon is explained by a multi path mechanism where electrooxidations of methanol and formaldehyde interfere. A study on platinum single crystals has shown DMM electrooxidation is strongly structure-sensitive. COads formation is kinetically favoured on Pt(100) and Pt(110). Terraces and steps of single crystals play an important role on the electrooxidation of DMM. In a general way, COads formation on (111) terraces comes from (100) steps, whereas on (100) terraces COads forms both on terraces and steps. A study of DMM electrooxydation on nanoparticles made by colloidal synthesis, indicates that PtRu(80-20) and PtRuMo(80-15-5) with 40% metal loading have the best activity. The increase of temperature and 1 M DMM concentration improve in a general way the fuel cell performances. Fuel cell tests on PtRu(80-20) show a power density of 35 mW cm-2, an OCV of 0. 57 V at 90°C, while on PtRuMo(80-15-5) : 29 mW cm-2 and 0. 75 V (OCV) at 110°C are obtained
Al, Cheikh Joumada. "Étude électrochimique de complexes moléculaires à base de métaux de transition non-précieux pour applications énergétiques". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS038/document.
Electrochemistry is becoming a major field in new energy storage and conversion technologies. Nowadays, the hydrogen evolution reaction (HER) is a reaction of great societal interest, which is at the heart of new technologies enabling the development of systems for the conversion of energy. However, some issues related to the use of noble metals (platinum, in particular) as catalysts have not been solved yet. This thesis is part of the scientific approach of the Research and Innovation in Electrochemistry for Energy (ERIEE) research group which has been interested for several years in the substitution of these noble metals by the use of transition metal based electro-catalysts. These molecules consist of organic compounds containing transition metals as an electro-active center for application in industrial electrolysers. This thesis focuses on the study of a family of molecular complexes based on transition metals (Co or Fe), the so-called clathrochelates, characterized by different chemical structures. The choice of the ligands constituting these complexes as well as the study of their functionalization processes on ad hoc substrates, constitute key elements in the apprehension of the resulting electro-catalytic performances.These electro-catalysts were studied both in solution (homogeneous phase) and functionalized at the surface of solid electrodes. Their physico-chemical properties as well as their electrocatalytic turnover for the hydrogen evolution reaction, have been systematically characterized.In particular, scanning electrochemical microscopy (SECM) allowed for the characterization of the electrocatalytic properties of modified electrodes at the local scale
Beliaeva, Kristina. "Captage et conversion électrochimique du CO2 dans des liquides ioniques et des solvants eutectiques profonds avec des catalyseurs à base de Pd". Electronic Thesis or Diss., Université Grenoble Alpes, 2023. http://www.theses.fr/2023GRALI094.
Carbon dioxide capture and utilization (CCU) is a way to decarbonize industrial sector. This technology provides a valorization of cheap carbon feedstock by its transformation to carbonaceous value-added chemicals. Multiple CO2 capture and utilization techniques exist to prevent the release of the greenhouse gas to the atmosphere. Here, we propose an integrated process of CO2 capture sequenced by electroconversion to C-based products in electrochemical cell. Electrochemical CO2 conversion is a promising method due to mild reaction conditions and possibility to power the reaction with electricity produced by renewable energy sources. This process necessitates the development of solvents capable to capture CO2 and to play a role of electrolyte during electrochemical reduction reaction. At the same time, efficient catalytic materials are vital for selective CO2 conversion to targeted product(s). The choice of capture solvent is usually based on CO2 capture ability, chemical and electrochemical stabilities, environmental issue and cost. Economically affordable deep eutectic solvent (DES) electrolytes seem to be promising candidates for CO2 capture and electroreduction because of good thermal and electrochemical stabilities, competitive CO2 uptake and large electrochemical windows. In this work, we focused on the development of novel deep eutectic solvent electrolytes for CO2 electroreduction with Pd-based electrocatalysts. Palladium proved its efficiency for selective conversion of carbon dioxide to C1 molecules such as carbon monoxide.During the thesis, we synthesized and electrochemically tested multiple DESs and Pd-based electrocatalysts with different morphologies and particle sizes to get more insights into reaction mechanism of CO2 electroreduction to C1 molecules. The implementation of different characterization techniques helped to study catalytic materials and DESs structures, to analyze gaseous and liquid reaction intermediates and products, and to understand main challenges of the studied system. Overall, this study is a one step forward the application of CO2ER (carbon dioxide electrochemical reduction) for valorisation of carbon dioxide and climate change mitigation
Cavoué, Thomas. "Électrocatalyseur à base d'argent pour la promotion électrochimique de la catalyse". Thesis, Lyon, 2020. https://n2t.net/ark:/47881/m6639p43.
The ethylene oxide (EO) is an essential building block for chemistry industry. It is produced by the ethylene epoxidation reaction over a silver-based catalyst. However, to achieve high selectivity, the industrial process uses chloride additives in the gas phase and alkaline moderators on the catalyst. The aim of this work is to develop a new environmentally-friendly route without using chloride compounds by using the concept of the Electrochemical Promotion of Catalysis (EPOC). This phenomenon allows to force, by applying small polarizations, the migration of ionic species contained in a solid electrolyte onto the catalyst surface and to in-situ modify its catalytic properties. Various Ag based catalytic coating have been deposited on dense membranes of Yttria Stabilized Zirconia (YSZ), an O2- ionic conductor. The pure silver films have shown a very poor activity toward the ethylene epoxidation but interesting properties for propene combustion in oxidative conditions, thanks to the EPOC phenomenon. To counteract the low activity of the pure silver films, composites coatings between Ag and YSZ have been synthetized in order to increase the porosity and the interface Ag/YSZ. These Ag/YSZ composite electrocatalysts achieved EO selectivity EO higher than 50%, without any promoter and under atmospheric pressure at 300°C, results never reported in the literature. However, this selective state can be maintained only for a few hours. In-situ observations by using an environmental transmission electron microscope have demonstrated the formation, under the reaction mixture, of small Ag2O clusters on the YSZ crystallites surface via a mechanism of evaporation/condensation. However, these very selective small nanoparticles (< 1 nm), quickly sinter at 300°C and lose their EO selectivity in favor of the CO2 production
Schild, Jérémy. "Catalyseurs supportés sur nanotubes de carbone pour la production d’énergies bas carbone". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASF021.
This thesis deals with the immobilization of molecular catalysts on the surface of carbon nanotubes. Different means have been used, using amphiphilic molecules containing a diacetylenic moiety and using polyaromatic amphiphilic molecules containing a pyrene moiety. These assemblies have been characterized by electrochemistry under different conditions in order to characterize the performances in hydrogen oxidation. The assembly using a polyaromatic moiety was then introduced as a complete fuel cell device with electrolyte to characterize the performance of it, with and without platinum. The results obtained are promising and allow a new vision of electrode optimization
Jacquet, Fabienne. "Obtention de l'hydroxy-4 dioxa-2,6 bicyclo (3. 3. 0) octanone-8 (1S, 4S, 5R) par voie catalytique, et selon un procédé d'électrosynthèse organique". Toulouse, INPT, 1986. http://www.theses.fr/1986INPT023G.
Elgrishi, Noemie. "Réduction électrochimique du CO2 en carburants catalysée par des complexes polypyridines moléculaires de métaux abondants". Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066103/document.
In an effort to work towards the development of cost-effective catalytic systems capable of storing sunlight energy in the form of chemical bonds using CO2 and water as substrates, homoleptic terpyridine complexes of first row transition metals were evaluated as catalysts for the electrocatalytic reduction of CO2. Ni and Co-based catalytic systems were shown to reduce CO2 to CO under the conditions tested. The Ni complex was found to exhibit selectivity for CO2 over proton reduction while the Co-system generated mixtures of CO and H2 with CO:H2 ratios being tuneable through variations of the applied overpotential. To investigate the parameters governing the competition for H+ reduction versus CO2 reduction, the cobalt bisterpyridine class of compounds was then evaluated as H+ reduction catalysts. Tuning the electronic of the ancillary ligand sphere resulted in a wide range of second-order rate constants for H+ reduction. When this class of compounds was next submitted to CO2 reduction conditions the less active catalysts for H+ reduction were the more selective towards CO2 reduction to CO. This represented the first report of the selectivity of a molecular system for CO2 reduction being controlled through turning off one of the competing reactions. Finally a strategy was proposed for immobilisation of homogeneous catalysts whereby a glassy carbon electrode is functionalised first by electro-grafting of the terpyridine ligand. The modified electrode can easily be metallated with cobalt and showed activity towards catalytic proton and CO2 reduction. The metal can be removed and the electrode re-metallated at will
Pimentel, Marcio. "Etudes de l'oxydation de phénol et crésols par l'oxydation électrochimique avancée en milieu homogène. Application au traitement d'effluent de l'industrie aéronautique". Phd thesis, Université Paris-Est, 2008. http://tel.archives-ouvertes.fr/tel-00742470.
Sahin, Nihat Ege. "Réduction électrochimique du dioxyde de carbone sur des électrocatalyseurs à base de cuivre". Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2313/document.
The anthropogenic emissions of carbon dioxide (CO2) are the major cause of global warming. The selective CO2 reduction reaction (CO2RR) of has been proposed as a promising, convenient and efficient method for sustainable energy conversion systems. The reduction of CO2 to energetically valuable products requires the use of an appropriate electrode material. This study focuses on the preparation of Cu-based electrocatalysts supported on different types of carbon materials such as Vulcan XC-72R, mesoporous carbon CMK-3, mesoporous carbon FDU-15 and tannin based mesoporous carbon IS2M for the CO2RR under mild conditions. Besides, Vulcan XC-72R carbon supported bimetallic copper/palladium alloy materials were prepared for increasing the Faradaic yield. These copper-based catalysts were electrochemically characterized and preparative electrolyses set at constant potential were carried out in order to investigate the reduction products distribution and Faradaic yields as a function of the applied potential and catalyst loading. Chemicals such as HCOOH, CO and H2 issued from the CO2RR, were determined with in-situ and ex-situ complementary (electro)analytical and spectroscopic techniques. The significant difference in the product distribution is probably due to the ensemble (geometry and ligand) effects in the bimetallic CuPd materials, and textural structure of the supporting substrates. Selective CO2 to-HCOOH conversion has been successfully undertaken on Cu50Pd50/C with 62 % Faradaic efficiency
Hong, Xiang. "Nouveaux catalyseurs hétérogènes chiraux pour le dédoublement cinétique hydrolytique des époxydesTERMINAUX". Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00770302.
Pellissier, Aymeric. "Elaboration et études physico-chimiques de nouveaux catalyseurs moléculaires ou composites pour l'électroréduction du CO2". Phd thesis, Université Joseph Fourier (Grenoble), 2005. http://tel.archives-ouvertes.fr/tel-00011066.
Pour l'approche « moléculaire », des catalyseurs bifonctionnels, nouveaux complexes hétérobimétalliques du type [Cl(CO)3Re(L)M(Cp*)Cl]+ (L = ligand bisdiimine ; M = Ir, Rh ; Cp* = η5-pentaméthyl-cyclopentadiényle) ont été synthétisés, et les interactions intramoléculaires entre les centres métalliques ont été étudiées. Des électrocatalyses préparatives de réduction du CO2 ont été conduites avec ces complexes en solution homogène mais aussi avec des électrodes modifiées obtenues par électropolymérisation anodique des pyrrole fonctionnalisés par ces mêmes complexes en milieu hydro-organique ou aqueux.
Pour la deuxième approche « inorganique », nous avons mis au point la synthèse des précurseurs adéquats pour élaborer des films fonctionnalisés par des complexes carbonyle de ruthénium cationiques [Ru(L)(CO)2(MeCN)2]2+ et [Ru(L)(CO)2(MeCN)]22+ (L = bipyridine substituée par des pyrroles), substrats nécessaires à la préparation de matériaux composites associant des nanoparticules métalliques et un polymère rédox. Ces complexes ont été déposés à la surface d'électrodes par électropolymérisation anodique des pyrroles et ont ainsi permis d'obtenir des films cationiques précurseurs de catalyseurs bifonctionnels.
Les résultats des électrocatalyses de réduction du CO2 avec les composés issus des deux approches montrent qu'il existe des effets coopératifs au sein des catalyseurs bifonctionnels.
Vigier, Fabrice. "Développement d'électrocatalyseurs pour l'oxydation directe de l'éthanol dans une pile à combustible à membrane (PEMFC)". Poitiers, 2002. http://www.theses.fr/2002POIT2301.
Cojocariu, Ana Mihaela. "Matériaux mésostructurés pour des applications dans les oxydations catalytiques : optimisation de la synthèse et des performances catalytiques". Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20030.
The objective of this thesis was the optimization of the synthesis and catalytic performances of Ti-containing materials in the oxidation with H2O2 of a wide range of model organic compounds. The original part is represented by the synthesis of SiO2-TiO2 mixed oxides by a non hydrolytic sol-gel procedure and their use in different catalytic reactions like: sulfoxidation, epoxidation of olefins, oxidation of aromatic hydrocarbons and phenols. These materials were compared with ordered mesoporous materials (Ti-MCM-41 and Ti-MCM-48) and microporous titanosilicalite TS-1. The non-hydrolytic sol-gel process based on the etherolysis and condensation of chloride precursors offers a simple one-step route to mesoporous SiO2-TiO2 xerogels with a good dispersion of Ti species and outstanding textural properties, without resorting to supercritical drying procedures as in the case of the mixed oxides obtained by a hydrolytic way. Moreover, these materials exhibited a remarkable catalytic activity in the oxidation with H2O2 of all the organic compounds investigated (significant conversions, good selectivities and H2O2 efficiencies). The catalysts were stable under operating conditions
Wang, Wei. "Matériaux à base de carbone pour la conversion et le stockage d'énergie électrochimique et chimique". Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAF059.
Energy conversion and storage have always been the two critical issues for human society. In this thesis, we focus on the development of sustainable carbon materials for effective electrochemical energy storage, especially for supercapacitors, and supported nickel catalysts for chemical energy conversion and storage, mainly on CO2 methanation. Two different biomass derived carbon structures, i.e. hierarchical carbon foam and graphene-like carbon nanosheets, have been synthesized and applied for supercapacitor. Exceptional electrochemical performances have been obtained. Meanwhile, nickel decorated macroscopic shape catalyst (Ni/OCF) has been developed for CO2 methanation with enhanced catalytic performance powered by electromagnetic induction heating (IH). The rapid energy regulation capability of IH system to jugulate the problem of temperature runaway has also been investigated in the last part using powdered alumina supported nickel catalyst for this exothermic reaction
Moumaneix, Lilian. "De l’élaboration de matériaux graphéniques tridimensionnels dopés à l’azote : vers des catalyseurs pour l’électroréduction de l’oxygène sans platine". Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0081.
The storage of energy in the form of dihydrogen is attracting growing interest in the scientific community as well as in the energy and transport industries. Proton exchange membrane fuel cells (PEMFC) convert this gas into electricity without harmful emission, at relatively low temperatures. Nowadays, catalysts are mainly made up of platinum nanoparticles, deposited on a microporous carbon material. However, this noble metal is a source of environmental and societal problems, and its supply is subject to geopolitical tensions and vagaries. This thesis work explores the possibility of using alternative materials without metals. Widely studied in the literature, carbon materials doped with nitrogen atoms have a catalytic activity for the oxygen reduction reaction (ORR), this reaction being the most limiting in PEMFCs. An elaboration method based on a solvothermal reaction between an alcohol and sodium, followed by a pyrolysis treatment, has been developed, yielding N-doped graphenic materials with a pronounced three-dimensional aspect and a very developed porosity. The study of the solvothermal reaction between 1-(2-hydroxyethyl)piperidine and sodium allowed to give a description of the reaction mechanism, by focusing on the analysis of the atmosphere composition within the solvothermal reactor during the reaction, and on the characterization of the solid solvothermal product. In addition, the influence of the pyrolysis conditions on the final material was studied using complementary and multi-scale characterization techniques, permitting to elaborate materials with good structural qualities and high specific surfaces. The catalytic activity of doped graphenic materials has been proven inside a PEMFC. Electrical power densities greater than 3 mW.cm-2 have been reached. Several parameters contributing to the improvement of the catalytic activity towards the ORR were identified, allowing to better target the future aspects on which to progress
Farina, Filippo. "Nanofilms de platine supportes sur des nanofibres de carbone et de nickel : nouveaux catalyseurs pour piles à combustible". Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS111.
Novel platinum thin film electrocatalysts for the oxygen reduction reaction of proton exchange membrane fuel cells were developed. These catalysts comprise platinum thin films deposited on carbon nanofibrous webs. Carbon nanofibres and nanobrush supports were prepared by electrospinning followed by thermal treatments for stabilisation and graphitisation. An innovative pulsed high overpotential electrodeposition method was developed to deposit platinum thin films both on carbon nanofibre and nanobrush supports, and also on highly oriented pyrolytic graphite, the planarity of which allowed detailed characterisation of the conformity, contiguity and thickness of the platinum films using atomic force and electron microscopy. These approaches led to self-standing nanofibre electrodes with porosity that was tuned to increasingly dense material from one side to the other, where the side presenting highest surface area was used to deposit platinum. The electrodes were characterised ex situ using cycling voltammetry where they demonstrated higher activity for the oxygen reduction reaction and greater durability on voltage cycling than conventional platinum on carbon catalysts. They were also assembled directly with a membrane and anode and characterised in situ in a single fuel cell. Thin platinum films were also prepared at the surface of nickel nanofibres using a novel approach to galvanic exchange assisted by microwaves, and a range of experimental parameters was investigated to determine their effect on the extent of exchange and the resulting platinum morphology. While the resulting nickel@platinum core@shell fibres demonstrated high electroactivity for the oxygen reduction reaction and were characterised as unsupported electrocatalysts at the cathode of a membrane electrode assembly, further work is required to stabilise them against nickel leaching from the catalyst to the electrolyte
Guenot, Benoit. "Etude de matériaux catalytiques pour la conversion électrochimique de l'énergie Clean hydrogen generation from the electrocatalytic oxidation of methanol inside a proton exchange membrane electrolysis cell (PEMEC): effect of methanol concentration and working temperature Electrochemical reforming of Dimethoxymethane in a Proton Exchange Membrane Electrolysis Cell: a way to generate clean hydrogen for low temperature fuel cells". Thesis, Montpellier, Ecole nationale supérieure de chimie, 2017. http://www.theses.fr/2017ENCM0004.
Hydrogen is a promising energy vector, particularly for energy storage from intermittent energy sources such as solar or wind. The development of its production methods and its electrochemical conversion represents a major challenge in the context of energy transition in which we live nowadays. Fuel cells and electrolyzers using PEM technology (Proton Exchange Membrane) are mature electrochemical energy conversion systems, while reversible systems capable of performing both functions – unitized regenerative fuel cells – are still in the early stage of development. Their main technological bottleneck is the design of a bifunctional oxygen electrode. The catalytic materials used in these systems are mainly noble metals and it is necessary to reduce as much as possible their loading in the electrodes to decrease the system cost. Three complementary aspects have been developed during this thesis. On the one hand, iridium and ruthenium oxides have been prepared by hydrothermal treatment in order to catalyze the oxygen evolution under electrolyzer operation. On the other hand, platinum-based catalysts supported on non-carbonaceous materials, especially titanium nitride, have been synthesized by colloidal routes, in order to catalyze the oxygen reduction under fuel cell operation. The combination of these materials is the first step towards the design of a bifunctional oxygen electrode. The third topic focuses on the production of hydrogen and proposes an alternative to the oxidation of water. The electrochemical oxidation of organic compounds such as methanol or dimethoxymethane using platinum and ruthenium based catalysts allows producing clean hydrogen with a lower electrical energy consumption compared to the electrolysis of water
Bodet, Hervé. "Céramiques denses comme réacteur membranaire pour l'oxydation ménagée des hydrocarbures". Lille 1, 2007. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2007/50376-2007-233.pdf.
Zhang, Lin. "Photoelectrocatalytic CO2 conversion in ionic liquid/aqueous mixture solution studied by scanning electrochemical microscopy". Thesis, Sorbonne université, 2020. https://accesdistant.sorbonne-universite.fr/login?url=http://theses-intra.upmc.fr/modules/resources/download/theses/2020SORUS122.pdf.
This thesis studies photoelectrochemical CO2 reduction reaction (PEC CO2RR) on p-type semiconductor CuCo2O4 addressing the cocatalytic role of imidazolium based RTILs by scanning photoelectrochemical microscopy (SPECM). CuCo2O4 was studied in different solvent supporting electrolyte systems including: aqueous solution (0.1 M KHCO3 and 0.1 M Na2SO4), binary mixture solution (25 vol.% [C2mim][BF4]/H2O and 25 vol.% [C4mim][BF4]/H2O) and pure RTILs ([C2mim][BF4], [C4mim][BF4]) to explore by SPECM the role of RTILs in CuCo2O4 semiconductor PEC performance. Significantly enhanced photoreduction current under both UV-vis and visible light illumination is reported in 25 vol.% [C2mim][BF4]/H2O solution. Only CO generated from PEC CO2RR was detected using an in-situ detection method based on a home-made dual tip optical fiber-ultramicroelectrode (OF-UME) and from bulk electrolysis under illumination. The formation of CO at potentials more positive than the thermodynamic value clearly points out that direct CO2 reduction on the electrode surface is not the mechanism. A possible reaction scheme for the PEC CO2RR mediated by [C2mim]+ is proposed. Thus, our results have demonstrated for the first time the cocatalytic role of [C2mim]+ for the PEC CO2RR. In addition, electrochemical CO2RR has also been studied on various synthesized transition metal–nitrogen–carbon catalysts (M–N–Cs) by rotating disk electrode. 25%Fe25%Co–N–C exhibited the best performance among the studied M–N–Cs in this thesis. The presence of Co sites in that catalyst provided synergic effect for the generation of distributed Fe-rich microcubes, which act as active sites in electrochemical CO2RR
Ngameni, Emmanuel. "Comportement électrochimique de biporphyrines adsorbées ou en solutions aqueuses acides : Etude du pouvoir catalytique de la biporphyrine de cobalt, CO::(2) FTF4, à l'égard de la réduction de l'oxygène". Brest, 1988. http://www.theses.fr/1988BRES2021.
Eskandari, Azin. "A preliminary theoretical and experimental study of a photo-electrochemical cell for solar hydrogen production". Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC104.
In order to meet the energy and climate challenge of the coming 21st century, one solution consists of developing processes for producing storable energy carriers by artificial photosynthesis to synthesize solar fuels, in particular hydrogen, in order to valorize the solar resource. The understanding of these processes and the achievement of high kinetic and energetic performances require the development of generic, robust and predictive knowledge models considering radiative transfer as a physical process controlling the process at several scales but also including the various other phenomena involved in the structure or reification of the model.In this PhD work, the photo-reactive process at the heart of the study was the photo-electrochemical cell. More complex than the simple photoreactor, with a photo-anode and a (photo)cathode, the photo-electrochemical cell spatially dissociates the oxidation and reduction steps. Based both on the existing literature (mainly in the field of electrochemistry) and by deploying the tools developed by the research team on radiative transfer and thermokinetic coupling formulation, it was possible to establish performance indicators of photo-electrochemical cells.In parallel to the establishment of this model, an experimental approach was undertaken based first on a commercial Grätzel-type cell (DS-PEC) indicating the general trends of such photon energy converters with in particular a drop in energy efficiency as a function of the incident photon flux density. A modular experimental device (Minucell) has also been developed and validated in order to characterize photo-anodes of different compositions such as chromophore impregnated TiO2 electrodes for operation in Grätzel cells or Fe2O3 hematite electrodes (SC-PEC) where the semiconductor plays both the functions of photon absorption and charge carrier conduction. Above all, the Minucell device allowed to test, characterize and model the behavior of a bio-inspired photo-electrochemical cell for H2 production using at the photo-anode a Ru-RuCat molecular catalyst (developed by ICMMO Orsay/CEA Saclay) and at the cathode a CoTAA catalyst (developed by LCEMCA Brest). Minucell was used to characterize each constituent element of a photo-electrochemical cell and then the cell as a whole confirming the trends and observations obtained on energy efficiencies.This preliminary work opens up a wide range of research prospects, lays common ground between electrochemistry and photo-reactive systems engineering, and provides insights into the design and kinetic and energy optimization of photo-electrochemical cells for the production of hydrogen and solar fuels
Diabaté, Donourou. "Synthèse et caractérisation de nanocatalyseurs à base de palladium pour l'oxydation du glucose et la réduction de l'oxygène moléculaire en milieu alcalin". Thesis, Poitiers, 2012. http://www.theses.fr/2012POIT2316/document.
This work concerns the development of nanocatalysts for a glucose/oxygen fuel in alkalinemedium. Therefore, carbon supported based palladium nanomaterials (Pd/C, PdAg/C and PdNi/C)were synthesized and characterized. Their electrocatalytic activity towards both the glucoseoxidation and oxygen reduction reaction (ORR) was studied. The electrode materials have beensynthesized by “water-in-oil microemulsion” and the physic-chemical characterizations providedinformation on their shape, morphology. Their average particle size remained less than 5 nm. Theoxygen reduction reaction performed with Rotation Ring Disk Electrode (RRDE) on these catalystsled to a four electrons process i.e. without hydrogen peroxide as intermediate (at ca. 0.85 V vs.RHE). Cycling voltammetry combined with Single Potential Alteration Infrared ReflectanceSpectroscopy (SPAIRS) was helpful to show that the primary product of the glucosedehydrogenation is the d-gluconolactone. The latter oxidation product undergoes hydrolysis togluconate in electrolytic solution. At high potential, the dissociative adsorption of glucose onPd70Ag30 gave carbon dioxide as another oxidation product
Lesage, Olivier. "Développement d'un procédé d'oxydation avancée pour le traitement d'effluents aqueux contaminés par des polluants réfractaires : étude d'un procédé de décharge plasma à pression atmosphérique couplé à un catalyseur supporté". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2014. http://tel.archives-ouvertes.fr/tel-01069381.
Sun, Shi-Gang. "Effet de la structure cristalline superficielle du platine dans le mécanisme de l'oxydation électrocatalytique de l'acide formique et du méthanol en milieu acide". Paris 6, 1986. http://www.theses.fr/1986PA066305.
Audichon, Thomas. "Synthèse et caractérisation de matériaux électrocatalytiques : activation anodique de l'eau dans un électrolyseur PEM". Thesis, Poitiers, 2014. http://www.theses.fr/2014POIT2292/document.
Hydrogen seems to be the most promising energetic vector in order to diversify the sources of energy production. Water splitting in a Proton Exchange Membrane Water Electrolyzer (PEMWE) provides a sustainable way of producing clean hydrogen. One of the main advantages of this technology based on the utilization of Membrane Electrode Assembling (MEA) is its potential coupling with renewable energy sources. However, the improvement of the catalytic activity of anode materials, their stability and the reduction of the noble metal content in their composition are required.During this thesis work, a new synthesis approach that consists in hydrolysis of metallic precursors in ethanol medium has been undertaken to prepare non-supported ruthenium-based nanomaterials. The addition of iridium to the nanocatalysts composition prevents the ruthenium oxide from dissolution without decreasing the initial activity of the anode catalyst. The best catalytic performance of MEAs in terms of current density, cell voltage and durability were observed with anode materials whose ruthenium molar composition is higher than 70 %. The partial substitution of precious metals (Ru and Ir) either by cerium or niobium with the purpose of decreasing the catalysts cost was also attempted. While the substitution with niobium introduces an amorphous phase in the material structure, the trimetallic materials containing cerium were shown to be crystalline. Furthermore, cerium contents up to 10 % allows maintaining the catalytic activity of the trimetallic anode close to that obtained with the bimetallic oxide material. Thus cerium appears as a promising metal to include in a suitable way on the composition of anode materials
Tonda-Mikiela, Pradel. "Étude des interfaces des nanocatalyseurs / glucose et enzymes / O2 pour une application biopile". Thesis, Poitiers, 2012. http://www.theses.fr/2012POIT2308/document.
The work developed in this thesis concerns the study of the behavior of redox reactions at the interfaces "nanocatalyst/glucose" and "enzyme/O2" for a hybrid Biofuel Cell. In this framework, a novel synthesis method of based gold and platinum nanoparticles has been achieved. These synthesized nanomaterials were characterized by different physicochemical techniques to determine their size, morphology and their dispersion in Vulcan XC72R used as substrate. The active surface area of each electrode material was determined by cyclic voltammetry and CO stripping. It has been shown that in the bimetallic catalyst gold promotes platinum activity towards the glucose oxidation. The bimetallic composition Au70Pt30 exhibits the better efficiency. The study by spectroelectrochemistry determined that the B-gluconolactone is the primary product of the glucose oxidation which proceeds at low potential by the dehydrogenation of anomeric carbon on platinum. The reduction reaction of O2 was catalyzed by an enzyme, bilirubin oxidase (BOD). Mediated electronic transfer was performed with two redox mediators, ABTS and an Osmium complex (Os). They have been encapsulated with the enzyme in a Nafion® matrix to construct the interfaces: BOD/ABTS/O2 and BOD/Os/O2. The voltammetric study of the mediators in phosphate buffer revealed two quasi-reversible systems with an apparent potential close to the theoretical potential of the T1 BOD center. Although hardly comparable in terms of current density with the Pt nanocatalyst the O2 reduction is a four electron reaction at the cathodes BOD/ABTS and BOD/Os which deliver an electrode potential close to the Nernst one
Özcan, Ali. "Degradation of hazardous organic compounds by using electro-fenton technology". Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00601213.
Silva, Rodrigo Garcia da. "Synthèse de nanomatériaux de morphologie coeur@coquille : application à l'oxydation électrocatalytique d'alcools en milieu alcalin". Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2274/document.
The present study proposes the synthesis of nanocatalysts based on palladium and platinum with high morphological organization and investigates their catalytic activity for the electrooxidation of ethanol, ethylene glycol, and glycerol in alkaline medium, seeking to understand the steps and mechanisms involved in these reactions. The nanomaterials were synthesized by the electrostatic self-assembly method and by the polyol microwave-assisted method. The goal was to obtain nanoparticles with morphology inspired by the core@shell-type systems, where the shell layer consists of platinum or palladium, and the core contains nickel, ruthenium, or tin. The electrocatalysts synthesized by the electrostatic self-assembly method were supported on Carbon Vulcan XC-72R or Multi-Walled Carbon Nanotubes (MWCNT, metal/carbon = 40:60). Morphology characterization data indicated uniform spherical shape nanoparticles with size ranging between 2 and 9 nm, besides, the specific morphology point to a particular degree of organization. However, the presence of the core@shell-type system was not confirmed through this analysis. CO-Stripping experiments demonstrated that the electrochemically active surface area of the bimetallic systems increased significantly, particularly for the nanocatalysts Ru@Pd/CNT and Ni@Pt/CNT, whose surface areas were 72.8 and 74.1 m²g-1Pd/Pt² respectively. Concerning the electrooxidation of C2 and C3 alcohols in alkaline medium (1.0 mol L-1 NaOH + 0.5 mol L-1 Fuel), M@Pt/CNT systems exhibited higher catalytic activity, especially when employing ethylene glycol as the fuel, which provided the highest catalytic current at constant potential (Eapp = -0.2 V vs. Hg/HgO/OH-). Specifically, the Ni@Pt/CNT nominal composition presented catalytic activity of 180 mA mg-1Pt. Electrochemical conversion studies were performed with the ethyleneglycol-Ru@Pt/CNT and glycerol-Ni@Pt/CNT systems, and after 12 hours of electrolysis, conversion reached values around 74% and 58%, respectively. Concerning the preferential mechanisms for glycerol electrooxidation, evaluated by liquid chromatography analysis, glycerate and tartronate ions were the major intermediates formed. The Ru@Pt/CNT nanocatalyst was selective for formate and oxalate ions. In addition, Ni@Pd/CNT generated mesoxalate ion during the reaction, suggesting a dual pathway for glycerol conversion, via tartronate and/or mesoxalate ions.The nanostructured materials synthesized by the polyol microwave-assisted method were supported on carbon Vulcan XC-72R with 20% wt. metallic loading. Briefly, the metal cores were synthesized separately for successive deposition of the noble metal, by employing the consecutive reductions technique. We investigated the palladium-based bimetallic catalysts, with ruthenium or nickel metallic cores, for the electrooxidation of ethylene glycol (0.1 mol L-1) in alkaline medium (0.1 mol L-1 NaOH). Morphology characterization data indicated that Pd/C catalyst displayed different nanoparticle shapes, and particle size ranged from 3 to 40 nm. Ru@Pd/C and Ni@Pd/C displayed spherical shape with particle size between 2 and 7 nm and between 3 and 10 nm, respectively. Ni@Pd/C exhibited the higher activity towards ethylene glycol oxidation in alkaline medium, reaching values of about 80 mA mg-1Pd at the end of chronoamperometry experiments. Overall, combination of the results obtained by liquid chromatography-mass spectrometry and infrared spectroscopy in situ showed that oxidation of glycolate ion is the limiting step for ethylene glycol conversion in alkaline medium in the presence of palladium-based catalysts. Lower amounts of glycolaldehyde, glyoxylate, and oxalate ions emerged at the end of electrolysis procedure, and no carbonate arose
O presente estudo tem como objetivo propor a síntese de nanocatalisadores à base de paládio e platina com elevada organização morfológica e investigar a referente atividade catalítica ao promover a eletro-oxidação do etanol, etilenoglicol e glicerol em meio alcalino, buscando assim compreender as etapas e mecanismos envolvidos perante estas reações. Neste contexto, os nanomateriais foram sintetizados pelo método de automontagem eletrostática e pelo método de poliol assistido por micro-ondas. Estas metodologias foram selecionadas a fim de obter nanopartículas com morfologia inspirada em sistemas do tipo core@shell (núcleo@casca), empregando átomos de paládio ou platina localizados na casca sobre núcleos de níquel, rutênio ou estanho. Os eletrocatalisadores sintetizados via automontagem eletrostática foram suportados em Carbono Vulcan XC-72R ou Nanotubos de Carbono de paredes múltiplas, com razão metal:carbono igual a 40:60. As nanopartículas obtidas apresentaram tamanho que variou entre 2-9 nm, formato esférico em quase sua totalidade e morfologia que indicava a presença de um determinado grau de organização; entretanto não foi confirmada a presença de sistemas do tipo core@shell. Experimentos de CO-Stripping demonstraram um aumento significativo da área eletroquimicamente ativa dos sistemas bimetálicos, com destaque para os nanocatalisadores Ru@Pd/NTC e Ni@Pt/NTC que apresentaram valores de 72,8 e 74,1 m² g-1Pd/Pt² respectivamente. Perante a eletro-oxidação dos álcoois C2 e C3 em meio alcalino (1,0 mol L-1 [NaOH] + 0,5 mol L-1 [Combustível]), os sistemas que apresentaram atividade catalítica mais elevada foram M@Pt/NTC, destacando o etilenoglicol como o combustível que propiciou a maior corrente catalítica quando submetido a potencial constante (E = -0,2 V vs. Hg/HgO/OH-). Mais especificamente, a composição Ni@Pt/NTC apresentou ao final dos experimentos de cronoamperometria um valor de atividade catalítica da ordem de 180 mA mg-1Pt. Os estudos de conversão eletroquímica demonstraram que ao empregar os sistemas etilenoglicol-Ru@Pt/NTC e glicerol-Ni@Pt/NTC atinge-se valores de conversão eletroquímica da ordem de 74% e 58%, respectivamente, após 12 horas de eletrólise a potencial controlado. Quanto aos mecanismos preferenciais de eletro-oxidação do glicerol, avaliados empregando análises de cromatografia líquida, foi verificada a formação majoritária dos íons glicerato e tartronato. Pontualmente, o nanocatalisador Ru@Pt/NTC indicou seletividade para a produção de íons formato e oxalato. Contudo, o catalisador Ni@Pd/NTC propiciou a eletrogeração do íon mesoxalato, sugerindo uma rota dupla de conversão do glicerol, via formação de íons tartronato e/ou mesoxalato.Os materiais nanoestruturados sintetizados via metodologia poliol assistida por micro-ondas foram suportados em Carbono Vulcan XC-72R com carga metálica igual a 20%. Especificamente para este caso, foram sintetizados os núcleos metálicos separadamente, para posterior deposição do metal nobre, empregando a técnica de reduções consecutivas. Foram investigados catalisadores bimetálicos à base de paládio, com núcleos de rutênio ou níquel, para promover a eletro-oxidação do etilenoglicol (0,1 mol L-1) em meio alcalino (0,1 mol L-1 NaOH). As nanopartículas de Pd/C apresentaram diferentes formatos e intervalo de tamanho entre 3-40nm. Para os catalisadores Ru@Pd/C e Ni@Pd/C foram verificados sistemas esféricos com variação do tamanho de partículas entre 2-7 nm e 3-10 nm, respectivamente. Os nanomateriais de composição nominal Ni@Pd/C exibiram elevada atividade para oxidar as moléculas de etilenoglicol em meio alcalino, atingindo valores da ordem de 80 mA mg-1Pd ao final dos experimentos de cronoamperometria
Anghel, Alina Maria. "Nouvelles méthodes d'électrodéposition d'un catalyseur employé dans une cellule photovoltaïque électrochimique". Mémoire, 2009. http://www.archipel.uqam.ca/2311/1/M10991.pdf.
De, Paz Héloïse. "Étude spectroélectrochimique de la réaction de réduction de l'oxygène sur une électrode de carbone modifiée avec une porphyrine de cobalt (CoTPP)". Mémoire, 2010. http://www.archipel.uqam.ca/3038/1/M11389.pdf.