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Sandström, R., Annamalai, A., Boulanger, N., Ekspong, J., Talyzin, A., Mühlbacher, I. & Wågberg, T. (2019). Evaluation of Fluorine and Sulfonic Acid Co-functionalized Graphene Oxide Membranes in Hydrogen Proton Exchange Membrane Fuel Cell Conditions. Sustainable Energy & Fuels, 3(7), 1790-1798
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
Sandström, R. (2019). Innovations in nanomaterials for proton exchange membrane fuel cells. (Doctoral dissertation). Umeå: Umeå University
Open this publication in new window or tab >>Innovations in nanomaterials for proton exchange membrane fuel cells
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Utveckling av nanomaterial för polymerelektrolytbränsleceller
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
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:nbn:se:umu:diva-158501 (URN)978-91-7855-044-9 (ISBN)
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
Sandström, R., Ekspong, J., Gracia-Espino, E. & Wågberg, T. (2019). Oxidatively Induced Exposure of Active Surface Area during Microwave Assisted Formation of Pt3Co Nanoparticles for Oxygen Reduction Reaction. RSC Advances, 9(31), 17979-17987
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
Sandström, R., Hu, G. & Wågberg, T. (2018). Compositional Evaluation of Coreduced Fe-Pt Metal Acetylacetonates as PEM Fuel Cell Cathode Catalyst. ACS Applied Energy Materials, 1(12), 7106-7115
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
Annamalai, A., Sandström, R., Gracia-Espino, E., Boulanger, N., Boily, J.-F., Muehlbacher, I. & Wågberg, T. (2018). Double donor Sb5+doped hematite (Fe3+) photoanodes for surface-enhanced PEC water splitting. Paper presented at 256th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nanoscience, Nanotechnology and Beyond, AUG 19-23, 2018, Boston, MA. Abstract of Papers of the American Chemical Society, 256
Open this publication in new window or tab >>Double donor Sb5+doped hematite (Fe3+) photoanodes for surface-enhanced PEC water splitting
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2018 (English)In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 256Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Physical Chemistry
Identifiers
urn:nbn:se:umu:diva-153144 (URN)000447600002312 ()
Conference
256th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nanoscience, Nanotechnology and Beyond, AUG 19-23, 2018, Boston, MA
Available from: 2018-11-07 Created: 2018-11-07 Last updated: 2018-11-07Bibliographically approved
Sandström, R., Ekspong, J., Annamalai, A., Sharifi, T., Klechikov, A. & Wågberg, T. (2018). Fabrication of microporous layer - free hierarchical gas diffusion electrode as a low Pt-loading PEMFC cathode by direct growth of helical carbon nanofibers. RSC Advances, 8(72), 41566-41574
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
Annamalai, A., Sandström, R., Gracia-Espino, E., Boulanger, N., Boily, J.-F., Mühlbacher, I., . . . Wågberg, T. (2018). Influence of Sb5+ as a Double Donor on Hematite (Fe3+) Photoanodes for Surface-Enhanced Photoelectrochemical Water Oxidation. ACS Applied Materials and Interfaces, 10(19), 16467-16473
Open this publication in new window or tab >>Influence of Sb5+ as a Double Donor on Hematite (Fe3+) Photoanodes for Surface-Enhanced Photoelectrochemical Water Oxidation
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2018 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 19, p. 16467-16473Article in journal (Refereed) Published
Abstract [en]

To exploit the full potential of hematite (α-Fe2O3) as an efficient photoanode for water oxidation, the redox processes occurring at the Fe2O3/electrolyte interface need to be studied in greater detail. Ex situ doping is an excellent technique to introduce dopants onto the photoanode surface and to modify the photoanode/electrolyte interface. In this context, we selected antimony (Sb5+) as the ex situ dopant because it is an effective electron donor and reduces recombination effects and concurrently utilize the possibility to tuning the surface charge and wettability. In the presence of Sb5+ states in Sb-doped Fe2O3 photoanodes, as confirmed by X-ray photoelectron spectroscopy, we observed a 10-fold increase in carrier concentration (1.1 × 1020 vs 1.3 × 1019 cm–3) and decreased photoanode/electrolyte charge transfer resistance (∼990 vs ∼3700 Ω). Furthermore, a broad range of surface characterization techniques such as Fourier-transform infrared spectroscopy, ζ-potential, and contact angle measurements reveal that changes in the surface hydroxyl groups following the ex situ doping also have an effect on the water splitting capability. Theoretical calculations suggest that Sb5+ can activate multiple Fe3+ ions simultaneously, in addition to increasing the surface charge and enhancing the electron/hole transport properties. To a greater extent, the Sb5+- surface-doped determines the interfacial properties of electrochemical charge transfer, leading to an efficient water oxidation mechanism.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
hematite, ex situ doping, Fe2O3-Sb, water splitting, Sb5+, Fe3+, surface charge, double donors
National Category
Materials Chemistry
Identifiers
urn:nbn:se:umu:diva-148990 (URN)10.1021/acsami.8b02147 (DOI)000432753800027 ()29663796 (PubMedID)2-s2.0-85046257587 (Scopus ID)
Funder
Swedish Research Council, 2017-04862Carl Tryggers foundation , CTS-16-161Swedish Energy Agency, 45419-1
Available from: 2018-06-14 Created: 2018-06-14 Last updated: 2018-06-19Bibliographically approved
Ekspong, J., Sandström, R., Rajukumar, L. P., Terrones, M., Wågberg, T. & Gracia-Espino, E. (2018). Stable Sulfur‐Intercalated 1T′ MoS2 on Graphitic Nanoribbons as Hydrogen Evolution Electrocatalyst. Advanced Functional Materials, 28(46), Article ID 1802744.
Open this publication in new window or tab >>Stable Sulfur‐Intercalated 1T′ MoS2 on Graphitic Nanoribbons as Hydrogen Evolution Electrocatalyst
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2018 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 28, no 46, article id 1802744Article in journal (Refereed) Published
Abstract [en]

The metastable 1T′ polymorph of molybdenum disulfide (MoS2) has shown excellent catalytic activity toward the hydrogen evolution reaction (HER) in water‐splitting applications. Its basal plane exhibits high catalytic activity comparable to the edges in 2H MoS2 and noble metal platinum. However, the production and application of this polymorph are limited by its lower energetic stability compared to the semiconducting 2H MoS2 phase. Here, the production of stable intercalated 1T′ MoS2 nanosheets attached on graphitic nanoribbons is reported. The intercalated 1T′ MoS2 exhibits a stoichiometric S:Mo ratio of 2.3 (±0.1):1 with an expanded interlayer distance of 10 Å caused by a sulfur‐rich intercalation agent and is stable at room temperature for several months even after drying. The composition, structure, and catalytic activity toward HER are investigated both experimentally and theoretically. It is concluded that the 1T′ MoS2 phase is stabilized by the intercalated agents, which further improves the basal planes′ catalytic activity toward HER.

Place, publisher, year, edition, pages
WILEY-VCH VERLAG GMBH, 2018
Keywords
DFT calculations, hydrogen evolution reaction, intercalation, MoS2, transition metal chalcogenides
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:umu:diva-154948 (URN)10.1002/adfm.201802744 (DOI)000449887300019 ()
Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2019-01-07Bibliographically approved
Sandström, R., Gracia-Espino, E., Hu, G., Shchukarev, A., Ma, J. & Wågberg, T. (2018). Yttria stabilized and surface activated platinum (PtxYOy) nanoparticles through rapid microwave assisted synthesis for oxygen reduction reaction. Nano Energy, 46, 141-149
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
Kwong, W. L., Gracia-Espino, E., Lee, C. C., Sandström, R., Wågberg, T. & Messinger, J. (2017). Cationic Vacancy Defects in Iron Phosphide: A Promising Route toward Efficient and Stable Hydrogen Evolution by Electrochemical Water Splitting. ChemSusChem, 10(22), 4544-4551
Open this publication in new window or tab >>Cationic Vacancy Defects in Iron Phosphide: A Promising Route toward Efficient and Stable Hydrogen Evolution by Electrochemical Water Splitting
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2017 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, no 22, p. 4544-4551Article in journal (Refereed) Published
Abstract [en]

Engineering the electronic properties of transition metal phosphides has shown great effectiveness in improving their intrinsic catalytic activity for the hydrogen evolution reaction (HER) in water splitting applications. Herein, we report for the first time, the creation of Fe vacancies as an approach to modulate the electronic structure of iron phosphide (FeP). The Fe vacancies were produced by chemical leaching of Mg that was introduced into FeP as "sacrificial dopant". The obtained Fe-vacancy-rich FeP nanoparticulate films, which were deposited on Ti foil, show excellent HER activity compared to pristine FeP and Mg-doped FeP, achieving a current density of 10 mAcm(-2) at overpotentials of 108 mV in 1 m KOH and 65 mV in 0.5 m H2SO4, with a near-100% Faradaic efficiency. Our theoretical and experimental analyses reveal that the improved HER activity originates from the presence of Fe vacancies, which lead to a synergistic modulation of the structural and electronic properties that result in a near-optimal hydrogen adsorption free energy and enhanced proton trapping. The success in catalytic improvement through the introduction of cationic vacancy defects has not only demonstrated the potential of Fe-vacancy-rich FeP as highly efficient, earth abundant HER catalyst, but also opens up an exciting pathway for activating other promising catalysts for electrochemical water splitting.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2017
Keywords
artificial photosynthesis, cation vacancy, iron phosphide, sacrificial dopant, solar fuels
National Category
Physical Chemistry
Identifiers
urn:nbn:se:umu:diva-143610 (URN)10.1002/cssc.201701565 (DOI)000416158500031 ()28980427 (PubMedID)
Available from: 2018-01-04 Created: 2018-01-04 Last updated: 2018-06-09Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-6830-2174

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