Дисертації з теми "Oxygen Electrochemistry"
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Bardini, Luca <1985>. "Oxygen: problems and solutions in electrochemistry." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5618/1/tesiDoc.pdf.
Повний текст джерелаBardini, Luca <1985>. "Oxygen: problems and solutions in electrochemistry." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5618/.
Повний текст джерелаSönmez, Turgut. "Studies of oxygen electrochemistry on spinel oxides." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/415516/.
Повний текст джерелаBikkarolla, Santosh Kumar. "Oxygen electrochemistry on inorganic/graphene hybrid materials for energy applications." Thesis, Ulster University, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.673823.
Повний текст джерелаKnoche, Krysti Lynn. "Density gradient films, lanthanide electrochemistry, and magnetic field effects on hydrogen evolution, oxygen reduction, and lanthanide electrochemistry." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/3124.
Повний текст джерелаTurner, Steven Christopher. "Electrochemical release of oxygen from metal complexes." Thesis, Heriot-Watt University, 1991. http://hdl.handle.net/10399/867.
Повний текст джерелаSiriwatcharapiboon, Wilai. "The electrochemistry of metal nanoparticles for oxygen reduction and nitrate/nitrite reduction." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4475/.
Повний текст джерелаYu, Kyle Kai-Hung. "Interfacial Electrochemistry of Copper and Spectro-Electrochemical Characterization of Oxygen Reduction Reaction." Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc103416/.
Повний текст джерелаSu, Yuhlong Oliver. "Electrochemistry of metalloporphyrins and their catalytic reduction of oxygen at carbon electrodes /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487260135354882.
Повний текст джерелаJorgensen, Mette Juhl. "Lanthanum manganate based cathodes for solid oxide fuel cells." Thesis, Keele University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343243.
Повний текст джерелаXiao, Neng. "Investigating Growth Mechanism of Potassium Superoxide in K-O2 Batteries and Improvements of Performance and Anode Stability upon Cycling." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1462890425.
Повний текст джерелаLi, Qian. "Electrochemical reduction of oxygen." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:2f37a1ae-dab0-4581-a8fd-e01ce59246c4.
Повний текст джерелаTrotochaud, Lena. "Structure-Composition-Activity Relationships in Transition-Metal Oxide and Oxyhydroxide Oxygen-Evolution Electrocatalysts." Thesis, University of Oregon, 2014. http://hdl.handle.net/1794/18312.
Повний текст джерела2015-03-29
Yin, Zhewen. "Non-precious Metal Catalysts for Oxygen Reduction Reaction in Alkaline Solutions." Scholar Commons, 2018. http://scholarcommons.usf.edu/etd/7250.
Повний текст джерелаSayeed, Md Abu. "Electrochemical fabrication of nanostructured metal oxides for the oxygen evolution reaction." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/116769/1/Md%20Abu_Sayeed_Thesis.pdf.
Повний текст джерелаSt, John Samuel. "Hierarchical Electrocatalyst Structure Control to Study Cathodic and Anodic Overpotential in Proton Exchange Membrane Fuel Cells." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384334674.
Повний текст джерелаStevens, Michaela. "Fundamentals and Industrial Applications: Understanding First Row Transition Metal (Oxy)Hydroxides as Oxygen Evolution Reaction Catalysts." Thesis, University of Oregon, 2017. http://hdl.handle.net/1794/22633.
Повний текст джерела10000-01-01
Singh, Deepika. "Non-Precious Metal Electrocatalysts for the Oxygen Reduction Reaction in Proton Exchange Membrane (PEM) Fuel Cells." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397727211.
Повний текст джерелаMOTOKI, YOSHIDA. "Synthesis of Ruthenium-based Water Oxidation Catalysts and Mechanistic Study." Thesis, KTH, Skolan för kemivetenskap (CHE), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-173843.
Повний текст джерелаKashyap, V. "High-performance Pt-free oxygen reduction reaction electrocatalysts derived from carbon supported spinel cobalt ferrite and Co/Fe-nitrogen coordinated active centers for advanced energy applications." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2019. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/4595.
Повний текст джерелаV.K acknowledges University Grant Commission (UGC), New Delhi, India, for research fellowship and K.S acknowledges Council of Scientific and Industrial Research (CSIR), New Delhi, India, for research funding (TLP003526).
AcSIR
Zhu, Huanfeng. "Experimental and Theoretical Aspects of Electrode Electrolyte Interfaces." Cleveland, Ohio : Case Western Reserve University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1259680393.
Повний текст джерелаTitle from PDF (viewed on 2009-12-30) Department of Chemistry Includes abstract Includes bibliographical references and appendices Available online via the OhioLINK ETD Center
Enman, Lisa. "Structure-Property Relationships in Mixed-Metal Oxides and (Oxy)Hydroxides for Energy Applications." Thesis, University of Oregon, 2019. http://hdl.handle.net/1794/24227.
Повний текст джерела2020-01-11
Devoille, Aline M. J. "New cofacial binuclear complexes for the oxygen reduction reaction and selective anion binding." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/9963.
Повний текст джерелаHedman, Jonas. "Characterization of reaction products in sodium-oxygen batteries : An electrolyte concentration study." Thesis, Uppsala universitet, Strukturkemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-317969.
Повний текст джерелаLiu, Zheng. "Synthesis and battery application of nanomaterials and the mechanism of O2 reduction in aprotic Li-O2 batteries." Thesis, University of St Andrews, 2016. http://hdl.handle.net/10023/15694.
Повний текст джерелаStrobl, Jonathan R. "ELECTROCATALYTIC STUDIES OF SUPEROXIDE AS AN INTERMEDIATE FOR THE OXYGEN REDUCTION REACTION IN BASIC ELECTROLYTES & THE REDUCTION OF SELENATE ON UNDERPOTENTIAL DEPOSITED Cu ON Au." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1595623881870564.
Повний текст джерелаHeidary, Nina [Verfasser], Anna [Akademischer Betreuer] Fischer, Anna [Gutachter] Fischer, Peter [Gutachter] Hildebrandt, and Ulla [Gutachter] Wollenberger. "IR spectro-electrochemistry of an adsorbed oxygen-tolerant [NiFe] hydrogenase on conductive surfaces / Nina Heidary ; Gutachter: Anna Fischer, Peter Hildebrandt, Ulla Wollenberger ; Betreuer: Anna Fischer." Berlin : Technische Universität Berlin, 2017. http://d-nb.info/1156013992/34.
Повний текст джерелаCrawford, Jessica F. "Using room-temperature liquid metals as a new reaction environment." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/232783/1/Jessica_Crawford_Thesis.pdf.
Повний текст джерелаWulff, Philip. "Principles of hydrogen catalysis in the presence of oxygen by a [NiFe] hydrogenase from E. coli." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:9e434467-d50b-484a-a17e-ef3091636269.
Повний текст джерелаvon, Deak Dieter G. "Heteroatom-containing Carbon Nanostructures as Oxygen Reduction Electrocatalysts for PEM and Direct Methanol Fuel Cells." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313085489.
Повний текст джерелаHeath, Rachel Sarah. "Studies of a 'blue' copper oxidase electrocatalyst." Thesis, University of Oxford, 2008. http://ora.ox.ac.uk/objects/uuid:e8359408-d3d4-4fe3-910a-cc69265a1546.
Повний текст джерелаShen, Xiaochen. "Exploiting Electrocatalyst for Energy Conversion: From Structure to Property." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1564492661618332.
Повний текст джерелаZhang, Yibin. "Study of Ruthenium and Ruthenium Oxide's Electrochemical Properties and Application as a Copper Diffusion Barrier." Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc4825/.
Повний текст джерелаSultana, Ummul Khair. "Electrochemical synthesis of water splitting nanomaterials." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/126972/1/Ummul%20Khair_Sultana_Thesis.pdf.
Повний текст джерелаLuo, Jin. "The Development and Biocompatibility of Low Temperature Co-Fired Ceramic (LTCC) for Microfluidic and Biosensor Applications." UKnowledge, 2014. http://uknowledge.uky.edu/cme_etds/30.
Повний текст джерелаHagelin, Alexander. "ZnO nanoparticles : synthesis of Ga-doped ZnO, oxygen gas sensing and quantum chemical investigation." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-64730.
Повний текст джерелаXiong, Linhongjia. "Amperometric gas sensing." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:a8dcbf36-14b6-4627-b380-3b81e83d446c.
Повний текст джерелаStelter, Michael. "Elektrokatalytische Sauerstoffreduktion an übergangsmetallporphyrinmodifizierten Graphitelektroden." Doctoral thesis, Universitätsbibliothek Chemnitz, 2001. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200100652.
Повний текст джерелаAceta, Yara. "Optimization of the interfacial electron transfer by nanostructuring and surface modification." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1S113.
Повний текст джерелаIt is the surface, not the bulk material that interacts with the surrounding environment; hence by altering the surface in a controlled manner we can modulate the properties of the material towards its environment. Aryldiazonium salts are suitable to tailor the surface properties since their structural diversity and their electrochemically-assisted bonding ability to modified conducting surfaces. This thesis focuses on the study of the electron transfer through different aryl layers by aryldiazonium electro-reduction at three different thickness levels, monolayer, near-monolayer, and multilayer, when the electroactive molecule is attached to the surface or in solution. Three different electrochemical methods have been used throughout this thesis, CV, EIS and SECM. The first study of this thesis focused on the investigation of the electrochemical properties of alkyl-ferrocene on-carbon monolayers in different solvents and its evaluation for improving the global charge density of carbon materials for energy storage applications. The second study used a bottom-up approach for the fabrication of well-organized surfaces. Carbon and gold substrates were modified by electro-reduction of a tetrahedral-shape preorganized aryldiazonium salt resulting in an ultrathin organic film that showed molecular sieving and current rectification properties towards redox probes in solution. The third study then focused on the oxygen reduction reaction and its intermediates, which are of general importance in natural and industrial processes. Detection of intermediates was achieved by SECM in a foot-printing strategy based on the use of different sensitive aryl multilayers. The role of the applied potential and electrolytes was investigated. Here we have demonstrated that the electrochemical properties of redox probes attached to a surface or in solution can be modulated by introducing aryl layers allowing fundamental research investigations of interest in fields such as energy storage and catalysis
Tang, Yongan. "SYNTHESIS AND ELECTROCATALYSIS OF METAL NANOMATERIALS." Miami University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=miami1402313477.
Повний текст джерелаNylén, Linda. "Influence of the electrolyte on the electrode reactions in the chlorate process." Doctoral thesis, KTH, Tillämpad elektrokemi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4681.
Повний текст джерелаFramställning av klorat är mycket energiintensiv och kräver stora mängder elenergi. Stigande elpriser, som dessutom ofta varierar under dygnet eller säsongsvis, gör att man vill reducera onödiga förluster samt ibland försöka anpassa produktionen så att man när elpriset är högt minskar den, för att sedan öka produktionen igen då elpriset sjunker. Denna flexibla drift kräver ny kunskap om hur elektroderna beter sig i ett större strömintervall än vad som tidigare varit av intresse. Målet med detta arbete var att, med fokus på elektrolytens betydelse, identifiera möjliga förbättringar för kloratprocessen och därmed minska energiförbrukningen. Studierna har i huvudsak varit experimentella men även matematisk modellering har använts. Ett brett strömintervall har undersökts för att bättre förstå fenomenen och för att även kunna använda resultaten då höga elpriser gör att man vill köra processen vid lägre laster än normalt. För att driften av anoden ska vara så energieffektiv som möjligt bör anodpotentialen inte överskrida den kritiska potentialen (Ecr), där den anodiska polarisationskurvan får en högre lutning (troligtvis pga Ru(VIII)-bildning) och bireaktionen syrgasutveckling ökar. I detta arbete har påverkan av olika elektrolytparametrar på Ecr undersökts. Det visade sig att en ökad kloridkoncentration och ökad temperatur sänkte Ecr. Trots att detta borde göra att Ecr lättare överskrids, blev inte detta fallet eftersom kloridoxidationen samtidigt gynnades. Slutsatsen blir därför att elektrolytparametrarna bör optimeras så att lägsta möjliga anodpotential uppnås, vilket då även gör att strömtätheten kan ökas utan att Ecr överskrids. Slutsatsen är vidare att polarisationskurvans högre lutning vid Ecr kan ha att göra med att rutenium oxiderat till rutenium(VIII) har lägre aktivitet för kloridoxidation. Vid full last visade sig katodens potential vara relativt oberoende av elektrolytsammansättningen trots att denna varierades kraftigt. Katodens sammansättning verkar vara viktigare att ta hänsyn till än elektrolytens för kunna åstadkomma en större energibesparing. Ett alternativ till att öka katodens aktivitet skulle vara att in-situ belägga elektrodytan med en katalytisk film. Försök gjordes att sätta till Y(III) till kloridelektrolyt för att under vätgasutveckling fälla ut en yttriumhydroxidfilm på den alkaliska katodytan. Yttriumhydroxidfilmen aktiverade vattenreduktion (vätgasutveckling) och inhiberade hypokloritreduktion, protonreduktion och nitratreduktion. De inhiberande egenskaperna är viktiga för att förhindra bireaktioner, vilka idag hindras av att Cr(VI) i elektrolyten reduceras på katoden och bildar en hindrande kromhydroxidfilm. Försöken med Y(III) visar att det finns goda möjligheter att hitta alternativ till det miljöfarliga Cr(VI). Kromattillsatsen i kloratelektrolyt ger förutom ett högt katodiskt strömutbyte även en buffrande effekt till elektrolyten. Effekten av buffert har undersökts för en av de anodiska bireaktionerna, syrgasutveckling ur vatten, samt för vätgasutvecklingen på katoden. Dessa system har modellerats för att bättre förstå samspelet mellan buffert, elektrodreaktioner och materietransport och resultaten har verifierats experimentellt. Kromatbufferten ökade gränsströmmen för katodisk H+-reduktion betydligt och katodöverpotentialen sjönk kraftigt vid lägre strömmar än gränsströmmen. Detta kan vara ett problem om överpotentialen sjunker så lågt att elektroden inte är katodiskt skyddad. För syrgasutvecklingen ökade närvaron av kromatbuffert gränsströmmen för syrgasutveckling ur OH-. Modellering av dessa system visar att de homogena reaktioner som var kopplade till elektrodreaktionerna inte var i jämvikt vid elektrodytan. Vidare visade det sig vara mycket viktigt med en bra upplösning av gränsskiktet vid elektrodytan, då den buffring som är viktig för elektrodreaktionerna sker i ett mycket tunt reaktionsskikt (nanometertjockt).
QC 20100901
PEZZOLATO, LORENZO. "Fe-N-C non-noble catalysts for applications in Fuel Cells and Metal Air Batteries." Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2809320.
Повний текст джерелаMa, Xiaoli. "Syntheses, structures, electrochemical and oxygen atom transfer properties of molybdenum and tungsten complexes with sulfur and selenium containing ligands." Doctoral thesis, [S.l.] : [s.n.], 2007. http://webdoc.sub.gwdg.de/diss/2007/ma.
Повний текст джерелаBlanes, Guàrdia Mireia. "Contribució al desenvolupament, optimització i regeneració de sensors d’oxigen per al control d’humitat en entorns d’alta temperatura." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/673223.
Повний текст джерелаThe work carried out in this doctoral thesis has been directed towards the development, optimization, and regeneration of oxygen sensors for the detection of humidity in high temperature environments to fulfill a specific goal: to implement a planar YSZ-based oxygen sensor inside an industrial furnace for quantifying the moisture present inside the chamber. A detailed study of the diffusive properties of the sensors has been undergone so that a geometry of the diffuser zone was determined to guarantee an adequate response of the sensors in the different measurement conditions. An electrochemical study of sensors in humid environments is presented. This study is based on the impedance spectroscopy (EIS) characterization of complete sensors. Three RC contributions have been characterized with clearly differentiated transition frequencies. The correlations between the obtained responses with different operating conditions of temperature and atmospheres, have allowed to assign the transition observed to high frequencies (ArcAF) with the triple phase boundaries (TPBs), the transition that appears to intermediate frequencies (ArcFM) has been related to the outer electrode and the observed transition to low frequencies (ArcBF) has been associated with the inner electrode. Studies carried out with different configurations of the sensors have allowed to evaluate the overlap of the different contributions and justify the different forms of the responses obtained in the measurements made at 2 electrodes. From these results, it has been possible to determine the effects of the degradation of the sensors, concentrated mainly on the deactivation of the TPBs generated by the adsorption of H2O molecules and the formation of platinum oxides. Finally, it has been possible to determine the degree of reversibility of the degradation of the sensors and to define a regenerative cycle. Regeneration by applying a cathodic potential has been shown to be much more effective and has longer-lasting effects.
Sanches, Cassandra Degelo. "Desempenho eletrocatalítico de eletrodos recobertos com filmes de quitosana frente a reação de redução de oxigênio em meio alcalino." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/75/75131/tde-14012010-105132/.
Повний текст джерелаThe oxygen reduction reaction was studied on smooth platinum and silver electrodes recovered with chitosan films and on Pt/C, Ag/C, MnyOx/C e TiO2/C porous electrodes in the presence or absence of chitosan-based films in alkaline electrolyte. These studies were carried out using steady state polarization measurement, obtained in a rotating disc electrode (RDE) and in alkaline fuel cells (AFC) (single cell), from which the corresponding Tafel curves and Levich plots were built. The studies carried out using the RDE had allowed establishing a good understanding of the catalytic activity and of the involved RRO mechanisms. A reduction in the electrocatalytic activity of the metallic electrodes and a change in the reaction mechanism (Pt and Ag smooth and porous) were caused by the presence of the chitosan films Thus, the RDE experiments showed that at high current densities the rate determining step of the ORR is the oxygen adsorption, in contrast to the electrodes without the film for which the rate determining step is the oxygen diffusion. In these cases it was not possible to calculate the number of electrons involved in the reaction. In the cases of the MnyOx/C and TiO2/C electrodes no significant change in the electrocatalytic activity, as well as in the reaction mechanism were caused due to the presence of the films (also in the number of electrons involved in the reaction), although a small increase in the Tafel coefficient values was noted. Also, tests of some of the materials as cathodes in AFC single cells with hydrogen/oxygen were carried out. These results showed that the performance is promising, although inferior to those of acid membrane electrolyte fuel cells.
ANNAMALAI, ABINAYA. "Electrochemical Energy Conversion Catalysts for Water Oxidation and CO2 Reduction." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1086344.
Повний текст джерелаLepesant, Mathieu. "Catalyseurs multimétalliques nano-organisés pour pile à combustible PEM." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENI052/document.
Повний текст джерелаThe decrease in cost of catalysts is one of the conditions necessary to make economically viable PEMFC technology to the general public. These catalysts, usually composed of platinum nanoparticles, are limited by cost, performance and durability. Nanostructuring is one of the possible solutions for these catalysts because it greatly increases the surface area, reducing the platinum loading and increase performance for the reaction of oxygen reduction, the most limiting in PEMFC technology.The works presented in this thesis were performed on two types of nanostructured particles (core-shell particles, hollow particles) based on platinum or platinum alloy. These particles have been studied, characterize in electrochemistry to 3 electrodes (rotating ring-disk electrode and half-cell assembly) and then integrated in fuel cell systems. We observed performance improvements offered by this type of electro-catalytic particles towards the reduction reaction of oxygen and then we started studying and optimize their integration into fuel cells and actual conditions of operation
Phuakkong, Oranit. "Design of carbon based structures for electrochemical applications." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0305/document.
Повний текст джерелаIn this thesis, the design of advanced carbon materials via electrochemical techniques and for electrochemical applications have been studied. In the first part, the concept of bipolar electrochemistry, which allows carrying out electrochemical reactions on a free-standing conductive object in an electric field, was employed to generate Janus-type objects. These objects are modified with a thermoresponsive hydrogel of poly(N-isopropylacrylamide) (pNIPAM) on one side and an electrophoretic deposition paint (EDP) on the other side. The results show that the length and the thickness of the hydrogel can be controlled by varying the electric field and the time of the experiment. The concept can be further generalized to other micro- and nanometer-sized objects, thus opening up perspectives for various applications.In the second part, the design of porous carbon structures for electrochemical applications was studied. The direct carbonization of non-porous zinc containing polymers was used to synthesize micro/mesoporous carbons with high surface area, pore volume. Non-porous zinc containing polymers with various types of dicarboxylic acid ligands prepared by solvothermal method were used as templates and starting materials. After carbonization porous carbons with various characteristics and properties were obtained. The synthesized porous carbon samples showed good electrochemical performance with high capacitance values. In addition, the derived materials exhibit excellent electrocatalytic activity with respect to the oxygen reduction reaction (ORR)
Ekström, Henrik. "Evaluating Cathode Catalysts in the Polymer Electrolyte Fuel Cell." Doctoral thesis, KTH, Tillämpad elektrokemi, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4413.
Повний текст джерелаI polymerelektrolytbränslecellen (PEMFC) omvandlas den kemiska energin hos vätgas och syrgas (luft) direkt till användbar elektrisk energi. På katoden (den positiva elektroden) krävs betydande mängder platina för att katalysera den tröga syrereduktionsreaktionen (ORR). Detta inverkar på kostnaden för högeffektsapplikationer, och för att göra en bred kommersialisering av PEMFC-teknologin möjlig skulle det vara önskvärt att minska den Pt-mängd som används för att katalysera ORR. I denna avhandling beskrivs ett antal tekniker som utvecklats för att undersöka katalytisk aktivitet på katoden i PEMFC. Metodiken liknar traditionella treelektrodexperiment i vätskeformig elektrolyt, med cyklisk voltammetri i inert gas, men med fördelen att försöken utförs i den riktiga PEMFC-miljön. I försök med porösa elektroder visades att det är möjligt att nå massaktiviteter nära 0.2 gPt/kW för potentialer över 0.65 V vid 60 ◦C, men massaktiviteterna kan bli betydligt lägre om temperaturen höjs till 80 ◦C, och om potentialsvepgränser och elektrodentillverkningsmetod ändras. Försök med modellelektroder resulterade i intressanta resultat rörande ORR i gränsskiktet Pt/Nafion. Genom att använda en ny metodik för att mäta på katalyserade plana elektroder av vitröst kol (glassy carbon), var det möjligt att se att gasernas fuktighet har en betydande inverkan på ORR-kinetiken hos Pt. Tafellutningarna blir brantare och aktiviteten minskar när inloppsgasernas fuktighetsgrad minskar. Eftersom den elektrokemiska arean hos Pt/Nafion-gränsskiktet inte ändrades, ansågs dessa kinetiska effekter bero på en lägre täckningsgrad av Ptoxider vid lägre fuktigheter, i kombination med lägre protonaktivitet. Genom att använda Nafionmembran belagda med nm-tjocka tvåskiktsmodellelektroder undersöktes hur Pt i kombination med TiO2 och andra metalloxider verkar i PEMFC-miljön. Kinetiskt sett hade tillsatsen av metalloxider ingen inre påverkan på aktiviteten, men vid jämförelse med porösa elektroder tycks den specifika ytaktiviteten vara högre hos en 3 nm film av Pt på Nafion än för en porös elektrod baserad på ∼4 nm Pt-korn belagda på ett kolbärarmaterial. Jämför man de cykliska voltammogrammen i N2, kan den högre aktiviteten tillskrivas en lägre grad av Pt-oxidbildning, vilket i sin tur kan bero på en storlekseffekt hos Pt-partiklarna. Försöken med dessa tvåskiktselektroder visade också att TiO2 kan verka som protonledande elektrolyt i PEMFC.
QC 20100706
Pearce, Paul-Emile. "AxIrO3 (A = Li, Na ou H) pour le stockage et la conversion électrochimique de l’énergie." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS313.
Повний текст джерелаThis thesis focuses on the study of the compound AxIrO3 as a versatile host for Li+, Na+ and H+. Its three-dimensional structure represents an interesting playing field for the fundamental study of the redox activity of the anionic network in oxides for Li+ and Na+ ion batteries. The lithiated phase can be obtained by high temperature ceramic synthesis in two stages whereas the sodiated phase could only be obtained electrochemically via IrO3. The protonated phase can be obtained by cation exchange of the lithiated phase or by reaction of water with IrO3. These last two phases had not been previously reported. The insertion processes were characterized by various techniques such as X-ray and neutron diffraction as well as X-ray absorption and photoemission spectroscopies to determine the structural changes associated with cationic and anionic oxidation processes. The results obtained allow us to deepen our understanding of a charge compensation mechanism that is still poorly understood. In addition, the study of the reactivity of IrO3 with an acidic aqueous media has made it possible to describe a mechanism for the electrocatalysis of the oxygen evolution reaction on the surface of iridium oxides and provides avenues for the development of new electrocatalysts based on iridium