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Innovations in nanomaterials for proton exchange membrane fuel cells
Umeå University, Faculty of Science and Technology, Department of Physics.ORCID iD: 0000-0002-6830-2174
2019 (English)Doctoral thesis, comprehensive summary (Other academic)Alternative title
Utveckling av nanomaterial för polymerelektrolytbränsleceller (Swedish)
Abstract [en]

Hydrogen technologies are rapidly receiving increased attention as it offers a renewable energy alternative to the current petroleum-based fuel infrastructure, considering that continued large-scale use of such fossil fuels will lead to disastrous impacts on our environment. The proton exchange membrane fuel cell should play a significant role in a hydrogen economy since it enables convenient and direct conversion of hydrogen into electricity, thus allowing the use of hydrogen in applications particularly suited for the transportation industry. To fully realize this, multiple engineering challenges as well as development of advanced nanomaterials must however be addressed.

In this thesis, we present discoveries of new innovative nanomaterials for proton exchange membrane fuel cells by targeting the entire membrane electrode assembly. Conceptually, we first propose new fabrication techniques of gas diffusion electrodes based on helical carbon nanofibers, where an enhanced three-phase boundary was noted in particular for hierarchical structures. The cathode catalyst, responsible for facilitating the sluggish oxygen reduction reaction, was further improved by the synthesis of platinum-based nanoparticles with an incorporated secondary metal (iron, yttrium and cobalt). Here, both solvothermal and high-temperature microwave syntheses were employed. Catalytic activities were improved compared to pure platinum and could be attributed to favorably shifted oxygen adsorption energies as a result of successful incorporation of the non-precious metal. As best exemplified by platinum-iron nanoparticles, the oxygen reduction reaction was highly sensitive to both metal composition and the type of crystal structure. Finally, a proton exchange membrane based on fluorine and sulfonic acid functionalized graphene oxide was prepared and tested in hydrogen fuel cell conditions, showing improvements such as lowered hydrogen permeation and better structural stability. Consequently, we have demonstrated that there is room for improvement of multiple components, suggesting that more powerful fuel cells can likely be anticipated in the future.

Place, publisher, year, edition, pages
Umeå: Umeå University , 2019. , p. 88
Keywords [en]
Fuel Cells, Membrane Electrode Assembly, Oxygen Reduction Reaction, Platinum alloy catalyst, Nanoparticles, Gas Diffusion Electrode, Proton Exchange Membrane
National Category
Energy Systems Nano Technology Other Materials Engineering Other Chemical Engineering Condensed Matter Physics
Research subject
Materials Science; Solid State Physics
Identifiers
URN: urn:nbn:se:umu:diva-158501ISBN: 978-91-7855-044-9 (print)OAI: oai:DiVA.org:umu-158501DiVA, id: diva2:1307843
Public defence
2019-05-28, N460, Naturvetarhuset, Umeå, 10:15 (English)
Opponent
Supervisors
Available from: 2019-05-07 Created: 2019-04-29 Last updated: 2019-05-06Bibliographically approved
List of papers
1. Direct support mixture painting, using Pd(0) organo-metallic compounds - an easy and environmentally sound approach to combine decoration and electrode preparation for fuel cells
Open this publication in new window or tab >>Direct support mixture painting, using Pd(0) organo-metallic compounds - an easy and environmentally sound approach to combine decoration and electrode preparation for fuel cells
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2014 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, no 48, p. 20973-20979Article in journal (Refereed) Published
Abstract [en]

An inventive, fast and straight-forward approach for the direct preparation of fuel cell electrodes has been developed and tested. Our approach avoids long catalyst preparation and post-synthesis treatment. It reduces the use of chemicals and thereby concomitantly lowers the environmental impact and improves cost efficiency. It combines decoration of the support by palladium nanoparticles with electrode preparation through a simple one-step ink-painting and annealing process. Composites have been investigated by high resolution transmission electron microscopy, scanning electron microscopy, and Xray diffraction. Crystalline particles are well-attached and well-distributed on the support. Particles are of few nanometers in size and spherical for decorated Vulcan whereas they are larger and irregularly shaped for decorated helical carbon nanofibers (HCNFs). Electrodes with a metal loading of 0.8 mg cm(-2) have been tested in a direct formic acid fuel cell. Both the Vulcan and the HCNF electrodes show a similar and high power output of up to 120 mW mg(-1). They also show similar performances in deactivation experiments conducted at 200 mA cm(-2) even when using only high purity grade formic acid. After deactivation the electrodes show no structural damage, making them superior to most commercial catalysts. The electrodes can be completely regenerated to initial activity by simple treatment with water. The easy regeneration process indicates that CO-adsorption on the fuel cell anode catalyst is not the main poisoning mechanism responsible for electrode degeneration.

National Category
Energy Systems
Identifiers
urn:nbn:se:umu:diva-98461 (URN)10.1039/c4ta04273e (DOI)000345531200070 ()2-s2.0-84911864610 (Scopus ID)
Available from: 2015-02-02 Created: 2015-01-22 Last updated: 2019-04-29Bibliographically approved
2. Fabrication of microporous layer - free hierarchical gas diffusion electrode as a low Pt-loading PEMFC cathode by direct growth of helical carbon nanofibers
Open this publication in new window or tab >>Fabrication of microporous layer - free hierarchical gas diffusion electrode as a low Pt-loading PEMFC cathode by direct growth of helical carbon nanofibers
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2018 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 72, p. 41566-41574Article in journal (Refereed) Published
Abstract [en]

Improving interfacial contact between each component in the proton exchange membrane fuel cell (PEMFC) can lead to a significant increase in power density and Pt utilization. In this work, the junction between the catalyst layer and gas diffusion layer (GDL) is greatly enhanced through direct attachment of helical carbon nanofibers, giving rise to a hierarchical structure within the electrical interconnections. The alternative novel GDL is produced by spraying a thin layer of Pd2C60 precursor on commercial carbon paper, followed by chemical vapor deposition growth resulting in a surface morphology of well-attached nanofibers surrounding the microfibers present in the commercial carbon paper. Subsequent solvothermal deposition of platinum nanoparticles allowed evaluation of its suitability as gas diffusion electrode in cathodic H-2/O-2 PEMFC environment. A combination of lowered charge transfer resistance and enhanced Pt-utilization is attributed to its unique wire-like appearance and its robust properties. The fabricated microporous layer - free GDL is suitable for relatively aggressive membrane electrode assembly fabrication procedures and is produced by industrially favorable techniques, rendering it capable of efficiently supporting small amounts of precious metal catalyst nanoparticles in various PEM applications.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2018
National Category
Materials Chemistry
Identifiers
urn:nbn:se:umu:diva-155124 (URN)10.1039/c8ra07569g (DOI)000453914300053 ()
Funder
The Kempe FoundationsSwedish Energy AgencySwedish Research Council
Available from: 2019-01-08 Created: 2019-01-08 Last updated: 2019-04-29Bibliographically approved
3. Compositional Evaluation of Coreduced Fe-Pt Metal Acetylacetonates as PEM Fuel Cell Cathode Catalyst
Open this publication in new window or tab >>Compositional Evaluation of Coreduced Fe-Pt Metal Acetylacetonates as PEM Fuel Cell Cathode Catalyst
2018 (English)In: ACS Applied Energy Materials, ISSN 2574-0962, Vol. 1, no 12, p. 7106-7115Article in journal (Refereed) Published
Abstract [en]

Platinum iron nanoparticles were produced by solvothermal coreduction of organic Fe and Pt precursor compounds and supported on conventional Vulcan XC 72. Evaluation of oxygen reduction performance reveals a highly active surface with up to 5 times the specific activity of commercial Pt Vulcan measured in O-2-saturated 0.1 M HClO4. A particle size of 5.5 nm for the best performing sample, produced from an initial metal ratio of 1:1, provided 28% higher mass activity than the commercial reference. Membrane electrode assemblies, optimized for both H-2/O-2 and direct formic acid fuel cells, were produced, and the PEM fuel cell cathodic performance displayed results with similar enhancements as its ex situ measured mass activity, although a delamination of the catalyst layer from the membrane could be observed even when employing a hot-pressing procedure during MEA fabrication. Physical characterizations including X-ray photoelectron spectroscopy and in situ X-ray diffraction reveal oxidized states of Fe incorporated into the disordered face-centered cubic Pt nanoparticles, supported by composition-dependent morphological changes as observed by transmission electron microscopy. The provided insight into fuel cell performance as well as CO-oxidation attributes are expected to assist in selecting suitable applications and operating conditions for such FePt type nanoparticles.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
platinum iron nanoparticles, proton exchange membrane fuel cell, oxygen reduction reaction, solvothermal coreduction, membrane electrode assembly, hydrogen energy
National Category
Materials Chemistry Inorganic Chemistry
Identifiers
urn:nbn:se:umu:diva-156900 (URN)10.1021/acsaem.8b01536 (DOI)000458706800053 ()
Funder
Swedish Research Council, 2017-04862Swedish Energy Agency, 45419-1
Available from: 2019-03-09 Created: 2019-03-09 Last updated: 2019-04-29Bibliographically approved
4. Yttria stabilized and surface activated platinum (PtxYOy) nanoparticles through rapid microwave assisted synthesis for oxygen reduction reaction
Open this publication in new window or tab >>Yttria stabilized and surface activated platinum (PtxYOy) nanoparticles through rapid microwave assisted synthesis for oxygen reduction reaction
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2018 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 46, p. 141-149Article in journal (Refereed) Published
Abstract [en]

The enhancement of platinum (Pt) based catalysts for the oxygen reduction reaction (ORR) by addition of rare earth metals represents a promising strategy to achieve high activity yet low content of the precious metal and concurrently addresses stability issues experienced by traditional late transition metal doping. Improvement in Pt utilization is essential for vehicular applications where material cost and abundancy is a great concern. Here we report a fast and efficient production route of yttria-stabilized platinum nanoparticles (PtxYOy) using a conventional household microwave oven. ORR performance showed a significant improvement and an optimum activity at a 3:1 Pt:Y ratio outperforming that of commercial Pt-Vulcan with a doubled specific activity. Incorporation of Y is evidenced by extended X-ray absorption fine structure and energy dispersive X-ray analysis, while significant amounts of integrated Y2O3 species are detected by X-ray photoelectron spectroscopy. Density functional theory calculations suggest surface migration and oxidation of Y, forming stable superficial yttrium oxide species with low negative enthalpies of formation. The robustness of PtxYOy is shown experimentally and through theoretical arguments demonstrating that surface yttria acts as a stabilizing agent and promoter of highly active ORR sites on the remaining Pt surface, surpassing even the Pt3Y alloy configuration.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Yttrium, Platinum, Nanoparticles, Catalysis, Hydrogen fuel cells, Oxygen reduction
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:umu:diva-144503 (URN)10.1016/j.nanoen.2018.01.038 (DOI)000427924000017 ()
Available from: 2018-02-05 Created: 2018-02-05 Last updated: 2019-04-29Bibliographically approved
5. Oxidatively Induced Exposure of Active Surface Area during Microwave Assisted Formation of Pt3Co Nanoparticles for Oxygen Reduction Reaction
Open this publication in new window or tab >>Oxidatively Induced Exposure of Active Surface Area during Microwave Assisted Formation of Pt3Co Nanoparticles for Oxygen Reduction Reaction
2019 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 31, p. 17979-17987Article in journal (Refereed) Published
Abstract [en]

The oxygen reduction reaction (ORR), the rate-limiting reaction in proton exchange membrane fuel cells, can efficiently be facilitated by properly manufactured platinum catalysts alloyed with late 3d transition metals. Herein we synthesize a platinum:cobalt nanoparticulate catalyst with a 3:1 atomic ratio by reduction of a dry organometallic precursor blend within a commercial household microwave oven. The formed nanoparticles are simultaneously anchored to a carbon black support that enables large Pt surface area. Two separate microwave treatment steps were employed, where step one constitutes a fast oxidative treatment for revealing active surface area while a reductive secondary annealing treatment promotes a Pt rich surface. The resulting Pt3Co/C catalyst (~3.4 nm) demonstrate an enhanced ORR activity directly attributed to incorporated Co with a specific and mass activity of 704 μA cm-2Pt and 352 A g-1Pt corresponding to an increase by 279 % and 66 % respectively compared to a commercial Pt/C (~1.8 nm) catalyst measured under identical conditions. The method´s simplicity, scalability and novelty is expected to further assist in Pt-Co development and bring the catalyst one step closer toward commercialization and utility in fuel cells.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
Keywords
Proton exchange membrane fuel cell, platinum cobalt, Oxygen reduction reaction, Microwave synthesis
National Category
Nano Technology Other Materials Engineering
Research subject
nanomaterials; nanoparticles; Materials Science
Identifiers
urn:nbn:se:umu:diva-158492 (URN)10.1039/c9ra02095k (DOI)000471914300054 ()
Funder
Swedish Research Council, 2017-04862ÅForsk (Ångpanneföreningen's Foundation for Research and Development), 15-483Swedish Energy Agency, 45419-1Swedish Research Council, 2018-03937Stiftelsen Olle Engkvist Byggmästare, 186-0637
Note

Originally included in thesis in manuscript form 

Available from: 2019-04-29 Created: 2019-04-29 Last updated: 2019-07-11Bibliographically approved
6. Microwave-Induced Structural Ordering of Resilient Nanostructured L10-FePt Catalysts for Oxygen Reduction Reaction
Open this publication in new window or tab >>Microwave-Induced Structural Ordering of Resilient Nanostructured L10-FePt Catalysts for Oxygen Reduction Reaction
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

We show how structurally ordered L10 face-centered tetragonal (fct) FePt nanoparticles are produced by a solid-state microwave-assisted synthesis method. The structural phase as well as the incorporated Fe into the nanoparticles is confirmed by X-ray diffraction and high resolution high-angle annular dark field scanning transmission electron microscopy experiments. The prepared particles exhibit a remarkable resilience toward crystallite growth at high temperatures. Directly correlated to the L10 phase, the best oxygen reduction reaction (ORR) characteristics are achieved for particles with a 1:1 Fe:Pt atomic ratio and an average size of ~2.9 nm where Pt-specific evaluation provided a high mass and specific activity of ~570 A/gPt and ~600 μA/cm2Pt respectively. Our results demonstrate that well-structured catalysts possessing activities vastly exceeding Pt/C (~210 A/gPt & ~250 μA/cm2Pt), can be synthesized through a fast and highly eco-friendly method. We note that the achieved mass activity represent a significant leap toward the theoretical maximum for fully ordered FePt nanoparticles.

Keywords
Proton exchange membrane fuel cell, platinum iron, Oxygen reduction reaction, microwave synthesis
National Category
Nano Technology Other Materials Engineering
Research subject
Materials Science; nanomaterials; nanoparticles; Solid State Physics
Identifiers
urn:nbn:se:umu:diva-158495 (URN)
Funder
Swedish Research Council, 2017-04862Swedish Energy Agency, 45419-1Interreg NordÅForsk (Ångpanneföreningen's Foundation for Research and Development), 15-483Swedish Research Council, 2016‐04412Swedish Foundation for Strategic Research , RIF 14‐0074Swedish Research Council, 2018-03937Stiftelsen Olle Engkvist Byggmästare, 186-0637
Available from: 2019-04-29 Created: 2019-04-29 Last updated: 2019-04-29
7. Evaluation of Fluorine and Sulfonic Acid Co-functionalized Graphene Oxide Membranes in Hydrogen Proton Exchange Membrane Fuel Cell Conditions
Open this publication in new window or tab >>Evaluation of Fluorine and Sulfonic Acid Co-functionalized Graphene Oxide Membranes in Hydrogen Proton Exchange Membrane Fuel Cell Conditions
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2019 (English)In: Sustainable Energy & Fuels, ISSN 2398-4902, Vol. 3, no 7, p. 1790-1798Article in journal (Refereed) Published
Abstract [en]

The use of graphene oxide (GO) based membranes consisting of self-assembled flakes with a lamellar structure represents an intriguing strategy to spatially separate reactants while facilitating proton transport in proton exchange membranes (PEM). Here we chemically modify GO to evaluate the role of fluorine and sulfonic acid groups on the performance of H2/O2 based PEM fuel cells. Mild fluorination is achieved by the presence of hydrogen fluoride during oxidation and subsequent sulfonation resulted in fluorine and SO3- co-functionalized GO. Membrane electrode assembly performance in low temperature and moderate humidity conditions suggested that both functional groups contribute to reduced H2 crossover compared to appropriate reference membranes. Moreover, fluorine groups promoted an enhanced hydrolytic stability while contributing to prevent structural degradation after constant potential experiments whereas sulfonic acid demonstrated a stabilizing effect by preserving proton conductivity.

Place, publisher, year, edition, pages
Royal Society of Medicine Press, 2019
Keywords
Proton exchange membrane, Fuel Cell, Graphene oxide, Hydrogen, Fluorine, Sulfonic acid
National Category
Nano Technology Other Chemical Engineering Other Materials Engineering Energy Systems
Research subject
nanomaterials
Identifiers
urn:nbn:se:umu:diva-158496 (URN)10.1039/C9SE00126C (DOI)000472980200014 ()
Funder
Swedish Research Council, 2017-04862Swedish Energy Agency, 45419-1ÅForsk (Ångpanneföreningen's Foundation for Research and Development), 15-483Interreg Nord
Note

Originally included in thesis in manuscript form

Available from: 2019-04-29 Created: 2019-04-29 Last updated: 2019-08-05Bibliographically approved

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