Influence of catalyst ink mixing procedures on catalyst layer properties and in-situ PEMFC performance

Despite the benefits of fuel cell technology its advancement to being commercially functional is hindered by a number of crucial factors. These factors are often associated with the lack of appropriate materials or manufacturing routes that would enable the cost of electricity per kWh to compete with existing technology. Whilst most research efforts have been directed towards developing more active catalysts, the amount of catalyst required in the fuel cell can be further reduced by improving the platinum utilisation in the membrane electrode assembly. The platinum utilisation is a strong function of the catalyst layer preparation step and there remains significant scope for optimisation of this step. Whereas significant work has been conducted into the different components of the catalyst ink there is limited work and understanding on the influence of the mixing method of the catalyst ink. This study will focus on the influence of the mixing technique on the catalyst ink properties and on the final fuel cell performance. Specifically, the study will investigate the effect of the three different mixing techniques on (i) catalyst ink quality (ii) the physical properties of the resultant catalyst layer and (iii) the in-situ electrochemical performance of the membrane electrode assembly. A large set of characterisation techniques were chosen to effectively study the step wise processing of the catalyst layer, and fuel cell performance. The results presented here include a comparison of the various mixing techniques and a comprehensive 2 x 2 factorial design into the individual techniques. The results suggest that high energy mixing is required for effective distribution of catalyst layer components, an even catalyst layer topography and a highly functional ionomer network which consequently, enhances performance. The mixing energy referred to involves prolonged mixing time, enhanced mixing intensity or a combination of the two. During bead milling of catalyst inks, high intensity mixing seems to be beneficial however, prolonged mixing time appears to be detrimental to the ionomer film structure. During high shear stirring and ultrasonic homogenisation of catalyst inks, the ink mixture significantly heats up. It has been observed that at higher temperatures, Nafion elongates and the contact with catalyst agglomerates is enhanced. High shear stirring of catalyst inks seems to be most effective at high agitation rates. High mixing energies result in high shear forces and in addition, high mixing temperatures which appear to be beneficial to establishing an effective catalyst/Nafion interface, enhancing the three phase boundary observed during in-situ testing. Ultrasonic homogenisation seems to be more effective at prolonged sonication times. Due to the erosive nature of ultrasonic dispersion, sufficient time is required to establish a well dispersed and distributed catalyst ink. However, the nature of particle size distribution resulting from ultrasonication shows that inks are unstable and is not recommended for high throughput processing. Overall, fuel cell performance is not significantly affected by the mixing step however; mixing does have an observable impact on catalyst layer formulation. Generally, when optimizing membrane electrode assembly fabrication, mixing parameters should be carefully chosen. This goes without saying that parameters need to be effectively studied before foregoing catalyst ink processing

Single Compartment Micro Direct Glucose Fuel Cell

Micro fuel cells have received considerable attention over the past decade due to their high efficiency, large energy density, rapid refuelling capability and their inherent non-polluting aspect. An air breathing abiotically catalyzed single compartment micro direct glucose fuel cell (SC-µDGFC) has been developed using microfabrication technologies. The single compartment of the fuel cell was shared by the anode and cathode that had an interdigitating comb electrodes configuration. The SC-µDGFC compartment was formed of polydimethylsiloxane (PDMS) which exhibits high permeability to oxygen and served as the membrane through which oxygen from ambient environment was able to permeate to the cathode. To minimize the losses associated with fuel crossover, two features were incorporated in the fuel cell: (i) silver was used as the catalyst to selectively reduce oxygen in the presence of glucose and (ii) cathodes were made 25-45µm higher than the anode to reduce access of oxygen to the anode with nickel or platinum catalyst. For 1M glucose/2M KOH solution, an initial OCV of 120-160mV was recorded, which gradually decreased with time and stabilized at 60-75mV. For a fuel cell tested without PDMS membrane, maximum OCV of 135mV and power density of 0.38µW/cm2 was obtained

Rapid Prototyping of Microfluidic Devices:Realization of Magnetic Micropumps, Fuel Cells and Protein Preconcentrators

With the growing importance of miniaturized energy applications and the development of micro Total Analysis Systems (μTAS), we have realized microfluidic devices, namely, magnetic micropumps, microfluidic fuel cells and membrane-based protein preconcentrators, all having high application potential in future. The choice of rapid prototyping microfabrication technologies and the selection of affordable materials are important aspects, when thinking of commercialization. Thus, we have employed powder blasting, polymer molding and assembly technologies during devices fabrication throughout the thesis. The first type of microfluidic device that we present is a poly(methyl methacrylate) (PMMA) ball-valve micropump with two different designs of the electromagnetic actuator, as optimized by the finite element method. The integration of a permanent magnet in a flexible polydimethylsiloxane (PDMS) membrane, which is clamped into PMMA structure, is proposed for providing a large stroke of the pumping membrane, making the micropump bubble-tolerant and self-priming Focusing on low power consumption for μTAS integration, another type of magnetic micropump with active valves is realized. It consists of a microfluidic chamber structure in glass that is assembled with a PDMS sheet, which comprises two valving membranes and a central actuation membrane, having each an integrated permanent magnet that is peristaltically actuated by a rotating arc-shaped permanent magnets assembly. A lumped circuit model is developed to predict and describe the frequency-dependent flow rate behavior for this type of pump. Powder blasting and PDMS molding rapid prototyping technologies are employed for realization of these two types of micropumps. Fuel cells with fluid delivery and removal options, having chemical reaction sites and electrode structures that can be realized in a microfluidic format, have high potential for applications. Therefore, microfluidic direct methanol fuel cells with embedded ion- permselective medium are studied and such type of fuel cell is realized by integrating a narrow Nafion strip in a molded elastomeric structure. A mechanical clamping assembly technology enables leakage-free operation and stable performance. The characterization reveals its output power density, using H2O2-based oxidant, is among the high-performance direct methanol fuel cells in microscale. Re-using the technology of the fuel cell chip, with its particular ion-permselective Nafion membrane and assembly method, we also have developed a protein preconcentrator with high purification performance. Our device can preconcentrate negatively charged biomolecules located at the anodic compartment side of the Nafion strip within only a few minutes with a high preconcentration factor. Moreover, a complex microfluidic finite element model is proposed to study and understand the physics of the preconcentration effect. Finally, we conclude the thesis with an outlook on future developments based on our work of the project and on the assembly technologies for microfluidic device integration

Hierarchical structured porous carbon materials : design, synthesis, and their application in energy conversion

Polymer electrolyte membrane fuel cells (PEMFC) are one of the most promising clean energy technologies under development. The major advantages include electrical efficiencies of up to 60 %, high energy densities (relative to batteries), and low emissions. However, the main obstacles to a broad commercialization of PEMFC are largely related to the limitations of the catalyst, typically platinum (Pt). Because of the high cost and limited resources of Pt, efforts are needed to identify metal-free catalysts or efficient carbon supports for the oxygen reduction reaction (ORR) in fuel cells. In the field of electrocatalysis, catalysts supported on high-surface area materials have been developed to increase their electrochemically active surface area. In addition, the performance of many electrocatalytical processes such as energy storage/-conversion, production of chemicals, biotechnological or environmental related applications depends on the structure and electronic conductivity of the used catalyst supports. The development of high effective catalyst supports could decrease the energy consumption of electrochemical processes and could lead to a reduction of greenhouse gases. Especially, hierarchical structured porous carbons with heteroatoms are proposed to increase the catalytic activity due to a high specific surface area and high electrical conductivity. Therefore, we suggest a very simple and cost effective way to produce conductive carbon supports coated with a nitrogen-containing carbon layer. The process works with the thermal decomposition of a suitable ionic liquid (IL) on the surface of different types of carbon materials (foam structures, graphene-like structures, CNTs, particles). The nitrogen content in the microporous coatings and therefore the electronic conductivity could be improved. In this work the preparation, characterization and also the fuel cell application of hierarchical structured carbon foams coated with a nitrogen-containing carbon layer are presented.Polymerelektrolytmembran-Brennstoffzellen (PEMFC) gehören zu den vielversprechendsten Technologien zur Bereitstellung von sauberer Energie. Die wesentlichen Vorteile sind hohe Wirkungsgrade (bis zu 60%), hohe Energiedichten (verglichen mit Batterien) und niedrige Emissionen. Allerdings wird eine breite Kommerzialisierung der PEM Brennstoffzellen durch die Verfügbarkeit der Platinkatalysatoren behindert. Wegen der hohen Kosten und der begrenzten Ressourcen an Pt sind Forschungen erforderlich um metallfreie Katalysatoren oder effiziente Kohleträger für die Sauerstoffreduktion (ORR) zu entwickeln. Im Bereich der Elektrokatalyse wurden Katalysatoren entwickelt, die auf Materialien mit großer Oberfläche geträgert sind um deren elektrochemisch aktive Fläche zu erhöhen. Darüber hinaus ist die Leistungsfähigkeit vieler elektrokatalytischer Prozesse wie Energiespeicherung/-umwandlung, die Produktion von Chemikalien, biotechnologischen oder umweltbezogenen Anwendungen abhängig von der Struktur und der elektronischen Leitfähigkeit der verwendeten Katalysatorträger. Die Entwicklung von hochwirksamen Katalysatorträgern könnte den Energieverbrauch der elektrochemischen Prozesse senken und dadurch die Erzeugung von Treibhausgasen verringern. Insbesondere poröse, hierarchisch strukturierte und mit Heteroatomen dotierte Kohlenstoffmaterialien werden eingesetzt, um die katalytische Aktivität aufgrund einer hohen spezifischen Oberfläche und elektrischen Leitfähigkeit zu erhöhen. Deshalb schlagen wir eine sehr einfache und kostengünstige Methode vor um Kohlenstoffträger mit einer leitfähigen stickstoffhaltigen Kohlenstoffschicht zu beschichteten. Das Verfahren arbeitet mit der thermischen Zersetzung einer geeigneten ionischen Flüssigkeit (IL) auf der Oberfläche von verschiedenen Kohlenstoffmaterialien (Schaumstrukturen, graphenartige Strukturen, CNTs, Partikel). Der Stickstoffgehalt in der mikroporösen Schicht und damit die elektronische Leitfähigkeit können dadurch gesteigert werden. In dieser Arbeit wird die Herstellung, Charakterisierung und Brennstoffzellenanwendung eines hierarchischen strukturierten Kohlenstoffschaums, welcher mit einer stickstoffhaltigen Kohlenstoffschicht beschichtet wurde, vorgestellt

Hierarchical structured porous carbon materials : design, synthesis, and their application in energy conversion

Polymer electrolyte membrane fuel cells (PEMFC) are one of the most promising clean energy technologies under development. The major advantages include electrical efficiencies of up to 60 %, high energy densities (relative to batteries), and low emissions. However, the main obstacles to a broad commercialization of PEMFC are largely related to the limitations of the catalyst, typically platinum (Pt). Because of the high cost and limited resources of Pt, efforts are needed to identify metal-free catalysts or efficient carbon supports for the oxygen reduction reaction (ORR) in fuel cells. In the field of electrocatalysis, catalysts supported on high-surface area materials have been developed to increase their electrochemically active surface area. In addition, the performance of many electrocatalytical processes such as energy storage/-conversion, production of chemicals, biotechnological or environmental related applications depends on the structure and electronic conductivity of the used catalyst supports. The development of high effective catalyst supports could decrease the energy consumption of electrochemical processes and could lead to a reduction of greenhouse gases. Especially, hierarchical structured porous carbons with heteroatoms are proposed to increase the catalytic activity due to a high specific surface area and high electrical conductivity. Therefore, we suggest a very simple and cost effective way to produce conductive carbon supports coated with a nitrogen-containing carbon layer. The process works with the thermal decomposition of a suitable ionic liquid (IL) on the surface of different types of carbon materials (foam structures, graphene-like structures, CNTs, particles). The nitrogen content in the microporous coatings and therefore the electronic conductivity could be improved. In this work the preparation, characterization and also the fuel cell application of hierarchical structured carbon foams coated with a nitrogen-containing carbon layer are presented.Polymerelektrolytmembran-Brennstoffzellen (PEMFC) gehören zu den vielversprechendsten Technologien zur Bereitstellung von sauberer Energie. Die wesentlichen Vorteile sind hohe Wirkungsgrade (bis zu 60%), hohe Energiedichten (verglichen mit Batterien) und niedrige Emissionen. Allerdings wird eine breite Kommerzialisierung der PEM Brennstoffzellen durch die Verfügbarkeit der Platinkatalysatoren behindert. Wegen der hohen Kosten und der begrenzten Ressourcen an Pt sind Forschungen erforderlich um metallfreie Katalysatoren oder effiziente Kohleträger für die Sauerstoffreduktion (ORR) zu entwickeln. Im Bereich der Elektrokatalyse wurden Katalysatoren entwickelt, die auf Materialien mit großer Oberfläche geträgert sind um deren elektrochemisch aktive Fläche zu erhöhen. Darüber hinaus ist die Leistungsfähigkeit vieler elektrokatalytischer Prozesse wie Energiespeicherung/-umwandlung, die Produktion von Chemikalien, biotechnologischen oder umweltbezogenen Anwendungen abhängig von der Struktur und der elektronischen Leitfähigkeit der verwendeten Katalysatorträger. Die Entwicklung von hochwirksamen Katalysatorträgern könnte den Energieverbrauch der elektrochemischen Prozesse senken und dadurch die Erzeugung von Treibhausgasen verringern. Insbesondere poröse, hierarchisch strukturierte und mit Heteroatomen dotierte Kohlenstoffmaterialien werden eingesetzt, um die katalytische Aktivität aufgrund einer hohen spezifischen Oberfläche und elektrischen Leitfähigkeit zu erhöhen. Deshalb schlagen wir eine sehr einfache und kostengünstige Methode vor um Kohlenstoffträger mit einer leitfähigen stickstoffhaltigen Kohlenstoffschicht zu beschichteten. Das Verfahren arbeitet mit der thermischen Zersetzung einer geeigneten ionischen Flüssigkeit (IL) auf der Oberfläche von verschiedenen Kohlenstoffmaterialien (Schaumstrukturen, graphenartige Strukturen, CNTs, Partikel). Der Stickstoffgehalt in der mikroporösen Schicht und damit die elektronische Leitfähigkeit können dadurch gesteigert werden. In dieser Arbeit wird die Herstellung, Charakterisierung und Brennstoffzellenanwendung eines hierarchischen strukturierten Kohlenstoffschaums, welcher mit einer stickstoffhaltigen Kohlenstoffschicht beschichtet wurde, vorgestellt

Hierarchical Membrane-Electrode Assembly and Metal-Free Cathode Catalysts for Polymer Electrolyte Membrane Fuel Cells

학위논문 (박사)-- 서울대학교 대학원 : 화학생물공학부, 2015. 2. 성영은.Fuel cells have come to occupy an important position in power sources of the next generation. They have risen as potential alternatives to alleviate our dependence on fossil fuels because of their high efficiency and low/no pollutant emissions. Among the various kinds of fuel cells, polymer electrolyte membrane fuel cells (PEMFCs) are the most encouraging for commercial applications due to their high efficiency, low operation temperature, and rapid start-up. Also PEMFC have been considered as the most effective solution of stealthy power sources for underwater vehicles. However, PEMFCs have not been completely commercialized yetowing to their high cost-components and low durability. In particular, the use of expensive/rare Pt metal as a catalyst becomes a matter of concern. Therefore it would be of great interest to investigate a more effective electrode structure for the higher performance through a careful design of membrane-electrode assembly (MEA), which is the heart of the PEMFC. Also, lots of significant efforts have been devoted to replacing Pt-based catalysts with inexpensive, more abundant nonprecious metal catalysts. The main theme of this thesis is the realization of high performance MEA in PEMFC: 1) by adopting a new catalyst layer structure, such as a three-dimensional ordered macroporous assembly, and 2) by applying novel metal-free catalyst to both acidic and alkaline polymer membrane electrolyte fuel cell. As mentioned above, a sophisticated design of the electrode in MEA must be needed and this subject in the previous work has not been sufficiently investigatedmore detailed study was necessary. Yet most studies for the new catalyst layer design have been confined to the half-cell data and only demonstrated the potential for practical use, however the half-cell is not a practical fuel cell device. Therefore in this thesis new approach for the electrode in MEA has presented and verified a realistic practical use in single-cell, MEA. Chapter 1 briefly describes the fundamental of fuel cell such as a principle, history, type and challenge. That includes a brief report about the application of PEMFC to silent power source for underwater platforms, like submarine. In chapter 2, this section introduces a large-area, hierarchical macroporous Pt electrode for use in practical devices such as MEA in PEMFCs, and this electrode has shown 85% higher performance than that of a conventional catalyst slurry ink based electrode with a similar Pt loading. These three-dimensional ordered macroporous materials could be attractive materials in electrochemical device because of the benefits from the periodic structure. Owing to their open and interconnected pore architecture, these electrodes maintained a good effective porosity, effective catalyst utilization and mass transfer, and satisfactory water management, while the concentration loss was minimized. This chapter provides useful information on development of attractive materials for electrochemical device, not restricted to the fuel cell electrode. In chapter 3, this part introduces a facile and gram-scale synthesis of graphitic carbon nitride hybrid as a metal-free hybrid catalyst for both acidic (proton as conducting reactants) and alkaline (hydroxide ion as conducting reactants) fuel cells, and this metal-free cathode electrode has exhibited an outstanding performance, i.e., 69% and 80% of commercial Pt/C performance in actual fuel cell devices using MEA with acidic and alkaline polymer electrolytes, respectively. Although numerous reports have been published on nonprecious metal catalysts for the oxygen reduction reaction of fuel cell cathode, few studies have demonstrated a realistic practical use of these catalysts in fuel cells, and furthermore, the reported performances are inferior to the performance obtained in this chapter. The fabrication method and remarkable performance of the single cell in this chapter are progresses toward realistic applications of metal-free materials in commercialized fuel cells.Abstract i Contents v List of Tables viii List of Figures ix Chapter 1. General Introduction 1 1.1 Fundamental of Fuel Cells 1 1.1.1 Principle 1 1.1.2 History 3 1.1.3 Types of Fuel Cells 5 1.2.4 Challenges of PEMFC 8 1.2 Polymer Electrolyte Membrane Fuel Cells 11 1.2.1 Cell Components 21 1.2.2 Electrode Reactions 16 1.2.3 Challenges of PEMFC 18 1.3 PEMFC as silent power source for underwater platforms 21 1.3.1 Fuel cell as air-independent propulsion (AIP) power system 21 1.3.2 Realization of PEMFC technology to submarines 24 1.4 References 31 Chapter 2. Ordered Macroporous Pt Electrode and Enhanced Mass Transfer in Fuel Cells Using Inverse Opal Structure 40 2.1 Abstract 40 2.2 Introduction 42 2.3 Experimental Section 48 2.4 Result and Discussion 54 2.5 Conclusions 85 2.6 References 86 Chapter 3. Realistic Applications of Metal-Free Hybrid Materials as Fuel Cells Electrodes: both Acidic and Alkaline Polymer Electrolytes 95 3.1 Abstract 95 3.2 Introduction 97 3.3 Experimental Section 101 3.4 Result and Discussion 110 3.5 Conclusions 137 3.6 References 138 Korean Abstract 144 List of Publications 148Docto

Experimental and numerical analysis of fuel cells

Fuel Cells are attractive power source for use in electronic applications. Physical phenomena (water generation, saturation effect in fuel cell, poisoning, and thermal stress) are studied that governs the operation of a Proton Exchange Membrane Fuel Cell (PEMFC) and Solid Oxide Fuel cell (SOFC). Additionally, experimental studies and numerical simulations on PEMFC gas flow channel, the determination of the impact of the single channel fuel cell are presented. Furthermore, preliminary study is done for the application of APS (Air Plasma Spray) to SOFC and adhesion of anode and cathode with electrolytes for the determination of parameters involved in manufacturing the components of fuel cell. The new aspects on physical phenomena are significantly different from the currently popular relationships used in fuel cells as they are simplified from simulation and experimental results. In prior work, the physical phenomena such as water generation, saturation effect in fuel cell, poisoning, and thermal stress etc. are either assumed or used as adjustment parameters to simplify them or to achieve best fits with polarization data. In this work, physical phenomena are not assumed but determined via newly developed experimental and numerical techniques. The experimental fixtures and procedures were used to find better ways to control parameters of gas flow channel configurations for optimizing gas flow rates and performance, and gas flow channel pressure swing for CO poisoning recovery. The experimental results reveal controlling parameters for the mentioned cases and innovative design for Fuel cells. Numerical modeling were used to 2D and later 3D for simplification of single channel fuel cell model, transient localized heating to the catalyst layer for CO recovery, thermal stress that developed during SOFC fabrication by High Temperature vacuum Tube Furnace (HTVTF), and Gas Diffusion Layer and Gas Flow Channel (GDL-GFC) interfacial conditions with results based on commonly used relationships from the PEMFC literature. The modeling works reveal substantial impact on predicted GDL saturation, and consequently cause a significant impact on cell performance. Computational parametric relations and polarization curve results are compared to experimental polarization behavior which achieved a comparable relation

Pt Nanophase supported catalysts and electrode systems for water electrolysis

Doctor Scientiae - DScIn this study novel composite electrodes were developed, in which the catalytic components were deposited in nanoparticulate form. The efficiency of the nanophase catalysts and membrane electrodes were tested in an important electrocatalytic process, namely hydrogen production by water electrolysis, for renewable energy systems. The activity of electrocatalytic nanostructured electrodes for hydrogen production by water electrolysis were compared with that of more conventional electrodes. Development of the methodology of preparing nanophase materials in a rapid, efficient and simple manner was investigated for potential application at industrial scale. Comparisons with industry standards were performed and electrodes with incorporated nanophases were characterized and evaluated for activity and durability.South Afric

Simulation study on PEM fuel cell gas diffusion layers using x-ray tomography based Lattice Boltzmann method

The Polymer Electrolyte Membrane (PEM) fuel cell has a great potential in leading the future energy generation due to its advantages of zero emissions, higher power density and efficiency. For a PEM fuel cell, the Membrane-Electrode Assembly (MEA) is the key component which consists of a membrane, two catalyst layers and two gas diffusion layers (GDL). The success of optimum PEM fuel cell power output relies on the mass transport to the electrode especially on the cathode side. The carbon based GDL is one of the most important components in the fuel cell since it has one of the basic roles of providing path ways for reactant gases transport to the catalyst layer as well as excess water removal. A detailed understanding and visualization of the GDL from micro-scale level is limited by traditional numerical tool such as CFD and experimental methods due to the complex geometry of the porous GDL structural. In order to take the actual geometry information of the porous GDL into consideration, the x-ray tomography technique is employed which is able to reconstructed the actual structure of the carbon paper or carbon cloth GDLs to three-dimensional digital binary image which can be read directly by the LB model to carry out the simulation. This research work contributes to develop the combined methodology of x-ray tomography based the three-dimensional single phase Lattice Boltzmann (LB) simulation. This newly developed methodology demonstrates its capacity of simulating the flow characteristics and transport phenomena in the porous media by dealing with collision of the particles at pore-scale. The results reveal the heterogeneous nature of the GDL structures which influence the transportation of the reactants in terms of physical parameters of the GDLs such as porosity, permeability and tortuosity. The compression effects on the carbon cloth GDLs have been investigated. The results show that the c applied compression pressure on the GDLs will have negative effects on average pore size, porosity as well as through-plane permeability. A compression pressure range is suggested by the results which gives optimum in-plane permeability to through-plane permeability. The compression effects on one-dimensional water and oxygen partial pressures in the main flow direction have been studied at low, medium and high current densities. It s been observed that the water and oxygen pressure drop across the GDL increase with increasing the compression pressure. Key Words: PEM fuel cell, GDL, LB simulation, SPSC, SPMC, x-ray tomography, carbon paper, carbon cloth, porosity, permeability, degree of anisotropy, tortuosity, flow transport

SYNTHESE ET CARACTERISATION DE NANOCOMPOSITES PLATINE/NANOFIBRES POUR ELECTRODES DE PILES A COMBUSTIBLE A ELECTROLYTE POLYMERE

The objective of this thesis is to develop corrosion resistant catalyst support materials that can potentially replace carbon in Polymer electrolyte fuel cells. Therefore, Nb doped TiO 2 and SnO 2 nanofibres and nanotubes were prepared by electrospinning and characterised by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, N 2 adsorption/desorption analysis and electronic conductivity measurements. The obtained Nb doped TiO 2 and SnO 2 one dimensional structures demonstrated higher conductivity and surface area than non-doped oxides. Pt nanoparticles were prepared using a modified microwave-assisted polyol method and deposited on the electrospun supports. Electrochemical characterisation of the obtained electrocatalysts was performed ex situ using a rotating disc electrode, and compared with a commercial carbon support (Vulcan XC-72R). Pt supported on Nb doped SnO 2 provided higher electrochemical stability in comparison to Pt on carbon. Thus, a cathode of Pt/Nb-SnO 2 prepared by spray-coating was integrated into Membrane Electrode Assembly (MEA) and characterised in situ in a single polymer electrolyte fuel cell. The MEA exhibited higher durability though lower power density compared to MEA with Pt/C based cathode. Sb doped SnO 2 nanotubes have higher conductivity than Nb doped material and when integrated into a cathode, provided enhanced power density in comparison to Nb-SnO 2 based cathode.Cette thèse s’inscrit dans le contexte général des efforts de recherche pour développer des supports de catalyseur résistant à la corrosion qui peuvent potentiellement remplacer le carbone dans les piles à combustible à électrolyte polymère. Des nanofibres et des nanotubes à base de TiO 2 et SnO 2 dopés par Nb ont été préparés par filage électrostatique et caractérisés par diffraction des rayons X, spectroscopie des photoélectrons de rayons X, spectroscopie Raman, mesures de surface spécifique et de conductivité électronique. Les nanofibres de TiO 2 et SnO 2 dopées par Nb présentent une conductivité et une surface spécifique supérieure à celle des oxydes non dopés. Des nanoparticules de platine ont été préparées en utilisant une méthode polyol modifié par micro-ondes, et déposées sur les supports fibreux. La caractérisation électrochimique des électrocatalyseurs ainsi obtenus a été réalisée ex situ par voltampérométrie en utilisant une électrode à disque tournant. Le catalyseur supporté, Pt sur SnO 2 dopé par Nb a présenté une stabilité électrochimique supérieure à celle d’un catalyseur Pt sur carbone commercial (Vulcan XC-72R). Une cathode Pt/Nb-SnO 2 préparée par pulvérisation a pu être intégrée dans un assemblage membrane-électrode (AME) et caractérisée in situ dans une cellule de pile à combustible à électrolyte polymère. L’AME a présenté une durée de vie plus élevée mais une densité de puissance plus faible qu’un AME contenant Pt/C. Les nanotubes de SnO 2 dopés par Sb ont une conductivité plus élevée que celle des matériaux dopés par Nb et lorsqu'ils sont intégrés dans une cathode, fournissent une densité de puissance accrue par rapport à une cathode à base de Nb-SnO 2