Made available in DSpace on 2014-10-09T12:26:36Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:22Z (GMT). No. of bitstreams: 0 / Os eletrocatalisadores Pt/C e Pt-Terras Raras/C (terras raras = La, Ce, Pr, Nd, Sm, Tb, Dy, Ho, Er, Tm, and Lu) foram preparados (20% em massa e razão atômica Pt-TR de 50:50) pelo método de redução por álcool, usando H2PtCl6.6H2O (Aldrich) e Terras Raras Cl3.xH2O (Aldrich) como fonte de metais, etileno glicol como solvente e agente redutor e, o carbono Vulcan XC72, como suporte. Os catalisadores foram caracterizados por espectroscopia de energia dispersiva de raios X (EDX), análises de difração de raios X (DRX) e microscopia de transmissão eletrônica (TEM). As análises por EDX mostraram que as razões atômicas dos diferentes eletrocatalisadores Pt-TR/C preparados foram similares às composições nominais de partida. Em todos os difratogramas, observa-se um pico largo em aproximadamente 2 = 25o o qual foi associado ao suporte de carbono Vulcan XC72 e quatro outros picos de difração em aproximadamente 2 = 40o, 47o, 67o e 82o os quais são associados aos planos (111), (200), (220) e (311), respectivamente, da estrutura cúbica de face centrada (CFC) de platina e suas ligas. Para os eletrocatalisadores Pt-TR/C também foram observadas fases nos difratogramas de raios X referentes aos óxidos de terras raras. Foram preparados eletrocatalisadores Pt-La/C com diferentes razões atômicas. Micrografias de transmissão eletrônica apresentaram uma razoável distribuição das partículas de Pt no suporte de carbono com algumas aglomerações, o que está de acordo com os resultados de difração de raios X. O desempenho para a oxidação de CO, metanol e etanol foi investigada através de voltametria cíclica, cronoamperometria e espectroscopia no infravermelho com transformada de Fourier. A atividade eletrocatalítica dos eletrocatalisadores Pt-TR/C, em especial PtLa/C, foram maiores que do Pt/C. A investigação por espectroscopia no infravermelho com transformada de Fourier para a oxidação de etanol com os eletrocatalisadores PtLa/C mostrou que o acetoaldeído e o ácido acético foram os principais produtos formados. O eletrocatalisador PtLa/C (30:70) apresentou melhores resultados para a reação de redução de oxigênio, oxidação de metanol e etanol, e a temperaturas superiores a 30°C para oxidação de monóxido de carbono. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-11-11T12:52:46Z No. of bitstreams: 0 / Made available in DSpace on 2016-11-11T12:52:46Z (GMT). No. of bitstreams: 0 / Os eletrocatalisadores Pd/C, Pd/C-15%ATO, PdAu/C-15%ATO (90:10, 70:30 e 50:50), PdIr/C-15%ATO (90:10, 70:30 e 50:50) e PdAuIr/C-15%ATO (90:5:5, 70:20:10 e 50:45:5) foram preparados pelo método de redução por borohidreto de sódio. Esses eletrocatalisadores foram caracterizados por espectroscopia de energia dispersiva de raios X (EDX), difração de raios X (DRX) e microscopia eletrônica de transmissão (MET), enquanto que as atividades eletrocatalíticas para a oxidação eletroquímica do ácido fórmico em meios ácido e alcalino foram investigadas por voltametria cíclica, cronoamperometria e experimentos em células a combustível de ácido fórmico direto (DFAFC) em meios ácido e alcalino a 100 ºC e 60 ºC, respectivamente. Os difratogramas de raios X dos eletrocatalisadores PdAu/C-15%ATO, PdIr/C-15%ATO e PdAuIr/C-15%ATO mostraram a presença de fase de estrutura cúbica de Pd (cfc), ligas de Pd-Au, Pd-Ir e Pd-Au-Ir, fases de carbono e SnO2. As micrografias eletrônicas de transmissão indicaram que as nanopartículas foram bem distribuídas sobre o suporte C-ATO e apresentaram alguns aglomerados. Os estudos eletroquímicos para oxidação de ácido fórmico foram realizados utilizando a técnica de camada fina porosa. Todos os eletrocatalisadores preparados foram testados em células a combustível unitárias alimentadas diretamente por ácido fórmico. Nos estudos comparativos entre os melhores eletrocatalisadores, o eletrocatalisador PdAuIr/C-15%ATO (50:45:5) em meios ácido e alcalino apresentou uma atividade eletrocatalítica superior para a oxidação eletroquímica do ácido fórmico em temperatura ambiente em comparação com o eletrocatalisador Pd/C-15%ATO e os outros eletrocatalisadores binários e ternários preparados. Os experimentos em uma DFAFC unitária ácida e alcalina, também, indicaram que o eletrocatalisador PdAuIr/C-15%ATO (90:5:5) apresentou melhor desempenho para oxidação eletroquímica do ácido fórmico a 100 ºC (meio ácido) e a 60 ºC (meio alcalino), respectivamente, em comparação com os demais eletrocatalisadores sintetizados. Esses resultados indicaram que a adição de Au e Ir ao Pd favorece a oxidação eletroquímica do ácido fórmico, esse efeito pode ser atribuído ao mecanismo bifuncional (a presença de ATO (Sb2O5·SnO2), óxidos de Au e Ir) associados ao efeito eletrônico (ligas de Pd-Au-Ir (cfc)). / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Indiana University-Purdue University Indianapolis (IUPUI) / The innovation and investigation of catalysts in proton exchange membrane fuel cells are included in this thesis. In the first part of this work, stability of the catalyst support of PEMFC catalyst is investigated. Nanoscale platinum particles were loaded on two different kinds of carbon supports, nano graphene sheets and functionalized carbon black/graphene hybrid were developed by the liquid phase reaction. The crystal structure of two kinds of catalysts was characterized by X-ray diffractometer (XRD). The morphology and particle size were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). Pt loading was measured by thermal gravimetric analysis (TGA). The Brunauer, Emmett and Teller (BET) method was applied to test the surface area of the catalysts. The electrochemical surface area (ECSA) and mass activity during oxygen reduction reaction (ORR) process for two kinds of catalyst were tested by cyclic voltammetry method under different conditions. The stability of the catalysts were tested by accelerated durability test (ADT). The results show that although the mass activity of Pt/graphene is much lower, the stability of it is much better than that of the commercial catalyst. After adding functionalized carbon black (FCB) as spacer, the stability of the catalyst is preserved and at the meantime, the mass activity becomes higher than 20% Pt/XC72 catalyst. The lower mass activity of both catalysts are due to the limitation of the electrolyte diffusion into the carbon support because of the aggregation nature of graphene nano-sheets. After introducing functional carbon black as spacer, the mass activity and ECSA increased dramatically which proved that FCB can be applied to prevent the restacking of graphene and hence solved the diffusion problem. In the meantime, the durability was still keeping the same as Pt/graphene catalyst. In the second part of the work, the restacking problem was solved by introducing FCB as spacers between functionalized graphene nanosheets. The same measurement was applied to test the electrochemical performance of Pt/FCB/FG catalyst. The new catalyst showed a higher mass activity compared to Pt/graphene catalyst which meant the restacking problem was partially solved. The durability of the Pt/FCB/FG catalyst was still excellent.

Στην παρούσα διατριβή αναπτύχθηκε ένα μοντέλο βασιζόμενο σε πρώτες αρχές με σκοπό την περιγραφή και την πρόβλεψη της πρωτονιακής αγωγιμότητας των πλήρως ενυδατωμένων μεμβρανών Nafion (το κυριότερο υλικό που χρησιμοποιείται ως ηλεκτρολύτης στις κυψέλες καυσίμου τύπου PEM) και των ιδιαίτερων χαρακτηριστικών αυτής, όπως τη γραμμική εξάρτηση από το πάχος της μεμβράνης, το δυναμικό του κελιού και τη μερική πίεση του υδρογόνου. Το μοντέλο εστιάζει στη μετανάστευση των πρωτονίων που είναι συνδεδεμένα στις σουλφονομάδες και χρησιμοποιεί την κατανομή φορτίου Poisson-Boltzmann γύρω από κάθε πρωτόνιο, σε συνδυασμό με την εξίσωση Gamow, που δίνει την πιθανότητα να συμβεί το φαινόμενο σήραγγος σε παραβολικό φράγμα δυναμικού. Προτείνεται ότι το μήκος που διανύεται κατά την πραγματοποίηση του φαινομένου σήραγγος ισούται με το μήκος κύματος του πρωτονίου και ότι κάθε πρωτόνιο περιβάλλεται από το νέφος Debye-Hückel. Το μοντέλο, που δεν εμπεριέχει προσαρμόσιμες παραμέτρους, λύνεται αναλυτικά και οι προβλέψεις του είναι σε ημιποσοτική συμφωνία με το πείραμα. Στις προβλέψεις αυτές συμπεριλαμβάνεται η τάξη μεγέθους της αγωγιμότητας, η γραμμική εξάρτηση της αγωγιμότητας με το πάχος της μεμβράνης, η εκθετική εξάρτηση από το δυναμικό και η ισχυρή εξάρτηση με τη μερική πίεση του υδρογόνου. Μελετήθηκε η κινητική, οι ταλαντώσεις και η ηλεκτροχημική ενίσχυση της οξείδωσης του CO σε καταλυτικό υμένιο Pt εναποτεθειμένο σε YSZ, χρησιμοποιώντας ως βάση την απόλυτη κλίμακα του ηλεκτροδίου του οξυγόνου. Βρέθηκε ότι η ηλεκτροχημική ενίσχυση είναι μικρή (ρ<3, Λ~300) όταν οι τιμές του δυναμικού του καταλύτη, UWR, είναι ανάμεσα σε 0.2 και 0.4 V και πολύ σημαντική (ρ~9, Λ~1500) όταν το UWR υπερβαίνει την τιμή 0.4 V. Η απότομη αλλαγή που παρατηρείται κατά την μετάβαση στην έντονη ηλεκτροχημική ενίσχυση συνοδεύεται και από απότομη αλλαγή στην κινητική της αντίδρασης και στο δυναμικό του καταλύτη. Μέσω της σύγκρισης των πειραματικών αποτελεσμάτων του κεφαλαίου και ανεξάρτητων μετρήσεων του έργου εξόδου μεταβάλλοντας το δυναμικό του καταλύτη για το ίδιο σύστημα, βρέθηκε ότι η μετάβαση οφείλεται στην έντονη μετανάστευση προωθητικών ειδών, Ο2-, από τη YSZ στην επιφάνεια του καταλύτη και την συνεπαγόμενη δημιουργία μιας πυκνής αποτελεσματικής διπλοστιβάδας στη διεπιφάνεια του καταλύτη με τα αέρια αντιδρώντα. Τέλος εξετάστηκε μια τροποποιημένη κυψέλη καυσίμου τύπου PEM η οποία λειτουργεί σε συνθήκες δηλητηρίασης από CO κατά την τριοδική λειτουργία. Στο τριοδικό κελί καυσίμου τύπου PEM εκτός της ανόδου και της καθόδου εισάγεται ένα τρίτο ηλεκτρόδιο το οποίο δημιουργεί ένα επιπλέον βοηθητικό κύκλωμα το οποίο λειτουργεί με ηλεκτρολυτικά ρεύματα και επιτρέπει τη λειτουργία της κυψέλης σε δυναμικά μεταξύ της ανόδου και της καθόδου ανέφικτα κατά τη συμβατική λειτουργία. Βρέθηκε ότι είναι δυνατό να ενισχυθεί η συνολική θερμοδυναμική ενεργειακή απόδοση όταν χρησιμοποιείται ως καύσιμο μίγμα αναμόρφωσης μεθανόλης που αντιστοιχεί σε συνθήκες έντονης δηλητηρίασης από CO. / In the present work a first principles model was developed to describe and predict the protonic conductivity of fully hydrated Nafion membranes and its peculiar non-linear dependence on membrane thickness, potential and PH2. The model focuses on the surface migration of protons between adjacent sulfonate groups and utilizes the Poisson-Boltzmann charge distribution around each proton combined with the basic Gamow equation of quantum mechanics for proton tunneling, for parabolic potential barrier. It was shown that the proton tunneling distance equals the proton wavelength and that each proton surrounded by its Debye-Hückel cloud behaves as a leaking nanobattery. The model, which contains no adjustable parameters, is solved analytically and its predictions are in semiquantitative agreement with experiment, including the magnitude of the conductivity, its linear increase with membrane thickness, its exponential increase with potential and its strong dependence on partial pressure of hydrogen. Moreover it was investigated the kinetics, rate oscillations and electrochemical promotion of CO oxidation on Pt deposited on YSZ using a standard oxygen reference electrode. It was found that electropromotion is small (ρ<3) when the catalyst potential UWR, is between 0.2 and 0.4V and very pronounced (ρ~9, Λ~1500) when UWR exceeds 0.4V. This sharp transition in the electropromotion behavior is accompanied by an abrupt change in reaction kinetics and in catalyst potential. It was shown via comparison with independent catalyst potential–catalyst work function measurements that the transition corresponds to the onset of extensive O2- spillover from YSZ onto the catalyst surface, and concomitant establishment of an effective double layer at the catalyst-gas interface, which is the cause of the highly active electropromoted state Furthermore it was studied a modified PEM fuel cell running in CO poisoning conditions by the triode operation. In addition to the anode and cathode, the triode PEM fuel cell introduces a third electrode together with an auxiliary circuit which is run in the electrolytic mode and permits fuel cell operation under previously inaccessible anode-cathode potential differences. It was found that it is possible to enhance the overall thermodynamic efficiency when it is used a methanol reformate mixture as a fuel, which corresponds to intense CO poisoning conditions.

Ce travail de thèse a concerné l’étude du comportement de nanoparticules d’électrocatalyseurs à base de Pt et Co déposées sur carbone de grande aire développée (Pt/C, PtCo/C et Pt3Co/C) en conditions représentative d’un fonctionnement à la cathode d’une pile à combustible à membrane échangeuse de protons. Dans une première phase, des électrodes modèles de ces matériaux ont été préparées sur des embouts de carbone vitreux compatibles avec une utilisation en montage d’électrode à disque tournant en milieu acide sulfurique, pour étudier l’évolution des performances électrochimiques (adsorption/désorption de l’hydrogène, Hupd, électrooxydation d’une monocouche de CO adsorbée à la surface du catalyseur : « CO-stripping », cinétique d’électroréduction de l’oxygène) après cyclage accéléré de potentiel (0,1 à 0,9 V vs. RHE et 0,6 à 0,9 V vs. RHE par créneaux d’une minute à chaque potentiel). Ces mesures électrochimiques ont été complétées par des observations statistiques par microscopie électronique en transmission (TEM) et fluorescence X (X-EDS) avant/après ces vieillissements sur des prélèvements représentatifs des couches actives. Les résultats montrent que le cobalt est irréversiblement oxydé/dissous des alliages Pt-Co et que la maturation d’Ostwald advient (pour le Pt) spécialement lorsque la borne inférieure de potentiel est fixée à 0,1 V vs. RHE. Ces mesures statistiques ont été confirmées par des expériences de MET en localisation identique (ILTEM), dans lesquelles les mêmes nanoparticules sont physiquement observées avant/après électrochimie réalisée sur la grille de microscopie[1]. Dans un second temps, des vieillissements identiques ont été mis en œuvre sur les mêmes matériaux électrocatalytiques en électrolyte polymère (Nafion), plus représentatif des conditions PEMFC, par utilisation d’une ultramicroélectrode à cavité et d’une « cellule sèche » dans laquelle le seul électrolyte est le Nafion (il n’y a donc pas d’électrolyte liquide). Dans ces conditions, plus proches des conditions réelles de fonctionnement d’une PEMFC, les mécanismes de dégradations sont différents de ceux observés en présence (d’excès) d’électrolyte liquide, parce que (entre autre), les ions Pt2+ formés à haut potentiel sont piégés dans le ionomère et donc plus faciles à redéposer sur les nanoparticules restantes. Le changement de morphologie (et composition) des nanoparticules de Pt/C (et Pt-Co/C) n’est donc pas identique en milieu H2SO4 et en milieu Nafion, ce qui montre que les tests réalisés en condition de laboratoire (en électrolyte liquide) ne sont pas forcément représentatifs de ce qui advient en PEMFC. Par extension, cette cellule sèche a été mise en œuvre pour mesurer les propriétés électrocatalytiques des différents électrocatalyseurs et, une fois encore, le milieu électrolyte liquide ne rend pas compte des performances observées en milieu « polymère ». Ces mesures ont été complétées par des observations statistiques en MET. Enfin, et il s’agit d’une innovation conséquente propre à ce travail, la méthode ILTEM a été employée pour des grilles de microscopie (supportant les électrocatalyseurs) n’ayant été utilisées qu’en interface avec un électrolyte polymère. Cela a permis de confirmer de manière quantitative et sur les mêmes grains de carbone / nanoparticules de Pt (ou Pt-Co) que les dégradations observées en milieu électrolyte liquide ne rendent pas compte de celles advenant en milieu polymère, la présence d’eau liquide jouant un rôle déterminant dans le premier cas (dissolution des espèces Pt2+/Co2+, oxydation du carbone, etc.). / In this study the oxygen reduction reaction (ORR) activity of Pt/C, Pt3Co/C and PtCo/C electrocatalysts supported on high surface area carbon (Vulcan XC-72) was correlated to their structural, morphological and compositional changes experienced after accelerated aging tests. The electrolytes were sulfuric acid at several concentrations and Nafion® ionomer membrane. These tests are based on different protocols that consisted of stepping the potential or keeping the electrode polarized at fixed potentials. The protocols which used steps consisted of stepping the potential during 1 minute for 15 hours overall successively between 0.9 and 0.1 V vs. ERH, 0.9 and 0.6 V vs. ERH, 1.05 and 0.10 V vs. ERH and 1.05 and 0.65 V vs. ERH. For the aging at fixed polarization (15 hours), the following potentials were used: 0.9, 0.6 and 0.1 V vs. ERH. After the 0.9 – 0.1 V vs. ERH aging in aqueous acidic solution, the Pt-Co/C catalysts showed no changes in the activity, while for Pt/C an improvement was seen. However for 1.05 – 0.10 V vs. ERH for Pt/C there was also an improvement while for the other catalysts there was a decrease of the activity. For all other protocols, a loss in activity was observed for all catalysts. Transmission electron microscopy (TEM) coupled with X-ray energy dispersive spectroscopy (X-EDS) analyses were used to characterize the as received and aged catalysts. A particularity of this work is the use of identical location transmission electron microscopy (ILTEM) technique, with the objective of analyzing the same electrode regions or particles before and after the accelerated ageing processes, so that it was possible to follow all the morphological, structural and compositional changes caused by the catalyst aging processes. The catalysts were compared before and after aging regarding the mean particle size, shape, particle density and composition and correlating these with the catalytic activity. Generally it was observed that the degradation correspond to carbon corrosion, coalescence, dissolution and re-precipitation of the catalyst particles for all aging protocols. The Pt/C catalyst, for example, for which an increase of particle mean size without any negative effect of agglomeration was observed, presented an improvement of the catalytic activity, while Pt-Co/C, in spite of the increase of the mean particle size and cobalt dissolution, presented worse or at most the same activity as that of the uncycled materials. Finally, the degradation mechanisms of the electrocatalysts aged in dry electrochemical environment using a Nafion® 115 membrane as polymer electrolyte were characterized by Identical Location Transmission Electron Microscopy, in conditions that perfectly mimic real PEMFC operation. The structural, morphological and compositional changes of the nanoparticles occurring during an accelerated stress test were bridged to changes of their intrinsic kinetics towards the oxygen reduction reaction in Nafion® 115 electrolyte, thanks to an ultramicroelectrode with cavity loaded with the catalyst. The unique setup used herein further enabled to compare the Nafion® environment with conventional liquid electrolyte in which accelerated stress tests are usually performed. Although the nanoparticles are modified upon ageing at Nafion® interface, the degradation processes are milder and different than those observed in liquid electrolyte, mostly following the absence of liquid water and the lack of ion mobility within the Nafion® membrane.

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Porous, conductive metallic nanostructures are required in several fields, such as energy conversion, low-cost sensors etc. This thesis reports on the development of an electrocatalytically active and conductive membrane for use in Polymer Electrolyte Membrane Fuel Cells (PEMFCs) and fabrication of low-cost substrates for Surface Enhanced Raman Spectroscopy (SERS). One of the main challenges facing large-scale deployment of PEMFCs currently is to fabricate a catalyst layer that minimizes platinum loading, maximizes eletrocatalytically active area, and maximizes tolerance to CO in the feed stream. Modeling the kinetics of platinum catalyzed half cell reactions occurring in a PEMFC using the kinetic theory of gases and incorporating appropriate sticking coefficients provides a revealing insight that there is scope for an order of magnitude increase in maximum current density achievable from PEMFCs. To accomplish this, losses due to concentration polarization in gas diffusion layers, which occur at high current densities, need to be eliminated. A novel catalyst design, based on a porous metallic nanostructure, which aims to overcome the limitations of concentration polarization as well as minimize the amount of platinum loading in PEMFCs is proposed. Fabrication steps involving controlled in-plane fusion of self-assembled arrays of core-shell gold-platinum nanoparticles (Au@Pt) is envisioned. The key steps involved being the development of a facile synthesis route to form Au@Pt nanoparticles with tunable platinum shell thicknesses in the 5 nm size range, the formation of large-scale 2D arrays of Au@Pt nanoparticles using guided self-assembly, and optimization of an RF plasma process to promote in-plane fusion of the nanoparticles to form porous, electrocatalytically active and electrically conductive membranes. This thesis consists of seven chapters. The first chapter provides an introduction into the topic of PEMFCs, some perspective on the current status of research and development of PEMFCs, and an outline of the thesis. The second chapter provides an overview on the methods used, characterization techniques employed and protocols followed for sample preparation. The third chapter describes the modelling of a PEMFC using the Kinetic theory of gases to arrive at an estimate of the maximum feasible current density, based on the kinetics of the electrocatalytic reactions. The fourth chapter presents the development of a simple protocol for synthesizing Au@Pt nanoparticles with control over platinum shell thicknesses from the sub monolayer coverage onwards. The results of spectroscopic and microscopic characterization establish the uniformity of coating and the absence of secondary nucleation. Chapter five describes the formation of a nanoporous, electrocatalytically active membrane by self-assembly to form bilayers of 2D arrays of Au@Pt nanoparticles and subsequent fusion using an RF plasma based process. The evolution of the electrocatalytic activity and electrical conductivity as a function of the duration of RF plasma treatment is monitored for Au@Pt nanoparticles with various extent of platinum coating. Spectroscopic, microscopic, electrical and cyclic voltammetry characterization of the samples at various stages were used to understand the structural evolution with RF plasma treatment duration and discussed. Next durability studies were carried out on the nanoporous, Au@Pt bilayer nanoparticle array with an optimum composition of Pt/Au atomic ratio of 0.88 treated to 16 minutes of argon plasma exposure. After this the novel catalyst membrane design of PEM fuel cell is revisited. Two different techniques are proposed so that the thin, nanoporous, metallic catalyst membrane achieves horizontal electronic resistance equivalent to that of the conventional gas diffusion layer with catalyst layer. The first technique proposes the introduction of gold coated polymeric mesh in between the thin, nanoporous, metallic catalyst membrane and bipolar plate and discusses the advantages. Later the gold coated polymeric mesh is introduced in a conventional membrane electrode assembly and efficiency of the polarization curves probed with and without the introduction of gold coated polymeric mesh. The second technique describes the results of fabrication of a nanoporous metallic membrane using multiple layers of 2D Au@Pt nanoparticle arrays at an optimum composition of Pt/Au atomic ratio of 0.88 to reduce the horizontal electronic resistance. Preliminary studies on the permeability of water through such membranes supported on a porous polycarbonate filter membrane are also presented. In chapter six, a simple reactive inkjet printing process for fabricating SERS active silver nanostructures on paper is presented. The process adapts a simple room temperature protocol, using tannic acid as the reducing agent, developed earlier in our group to fabricate porous silver nanostructures on paper using a commercial office inkjet printer. The results of SERS characterization, spectroscopic and microscopic characterizations of the samples and the comparison of the substrate’s long-term performance with respect to a substrate fabricated using sodium borohydride as the reducing agent is discussed. Preliminary findings on attempts to fabricate a conductive silver network using RF plasma induced fusion area also presented. Chapter seven provides a summary of the results, draws conclusions and a perspective on work required to accomplish the goals of incorporating the porous metallic nanostructures into PEMFCs.

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