Grazing-incident neutron scattering to access catalyst for polymer electrolyte fuel cell

Ueda, Shigenori; Koizumi, Satoshi; Ohira, Akihiro; Kuroda, Seiichi; Frielinghaus, Henrich

doi:10.1016/j.physb.2017.12.061

Cited by 15 publications

(25 citation statements)

References 4 publications

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“…The reflectivity is especially sensitive to the mass distribution (db/ dz) along the normal vector of the surface. For that purpose, in a previous study we simulated local structures of the catalyst on an Si substrate, by sputtering and spin-coating methods, and then performed GISANS and reflectivity measurements (Ueda et al, 2018).…”

Section: Further Informationmentioning

confidence: 99%

“…By comparing with results obtained by the GISANS and reflectivity methods, we discuss the microphase structure and water distribution in the ionomer thin layer. Ueda et al (2018) performed GISANS and neutron reflectivity measurements on a model catalyst, i.e. the Nafion ionomer was spread by the spin-coating method on platinum and silicon substrates with thickness 10 nm.…”

Section: Further Informationmentioning

confidence: 99%

“…As a result of observations by contrast variation SANS and SEM, we find for the fully humidified catalyst that (i) the thickness of the ionomer thin layer is about 5 nm, (ii) the average water content is about 17 wt%, and (iii) the layer is surrounded by air (void). Further information, such as the water distribution on the surface of the Pt or carbon or the microphase separation in the thin layer, can be achieved by grazing-incidence SANS (GISANS) including reflectivity, as reported by Ueda et al (2018).…”

Section: Introductionmentioning

confidence: 99%

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Microstructure and water distribution in catalysts for polymer electrolyte fuel cells, elucidated by contrast variation small-angle neutron scattering

Koizumi¹,

Ueda²,

Inada³

et al. 2019

J Appl Cryst

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By using small-angle neutron scattering (SANS) reinforced by scanning electron microscopy, the fine structure of catalysts for polymer electrolyte fuel cells has been investigated. The experimental data resulting from contrast variation with mixed light and heavy water (H 2 O/D 2 O) are well described by a core-shell model with fluctuations in concentration between water and Nafion. In particular, SANS obtained with the mixed water ratio 30/70, which corresponds to a matching point between mixed water and Nafion, shows a broad scattering maximum, which is attributed to a 5 nm-thick Nafion shell on the surface of the larger carbon particles. After swelling by water, the ionomer layer absorbs water at the 17 wt% level. By changing the H 2 O/D 2 O ratio, it was further confirmed that the catalyst with the ionomer exhibits water repellence, whereas the bare catalyst without the ionomer is wetted by water. Because it is very difficult to extract more information, for instance regarding the Pt-Nafion interactions, by means of small-angle scattering, reflectometry and grazing-incidence scattering experiments with neutrons should be attempted on a model catalyst prepared on a flat substrate. research papers J. Appl. Cryst. (2019). 52, 791-799 Satoshi Koizumi et al. SANS study of polymer electrolyte fuel cell catalysts 797

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Section: Further Informationmentioning

confidence: 99%

Section: Further Informationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Microstructure and water distribution in catalysts for polymer electrolyte fuel cells, elucidated by contrast variation small-angle neutron scattering

Koizumi¹,

Ueda²,

Inada³

et al. 2019

J Appl Cryst

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“…This advanced scattering technique is a nondestructive method, which probes structures in a range from nanometer to micrometer with a high statistical relevance since the neutron beam has a macroscopic footprint on the probed samples. [35,[39][40][41] In more detail, both films are first measured in air to see the difference of the inner morphology. Subsequent GISANS measurements during exposure to D 2 O vapor (after stabilization at 50 °C for 2 h) are used to compare the deformation of the nanostructures caused by water infiltration.…”

Section: Structure Deformationmentioning

confidence: 99%

“…To probe the inner morphology of the titania nanostructures annealed in the two different atmospheres, GISANS measurements are performed. This advanced scattering technique is a nondestructive method, which probes structures in a range from nanometer to micrometer with a high statistical relevance since the neutron beam has a macroscopic footprint on the probed samples . In more detail, both films are first measured in air to see the difference of the inner morphology.…”

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Deformation of Mesoporous Titania Nanostructures in Contact with D₂O Vapor

Song

Rawolle

Hohn

et al. 2018

Small

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For many applications, mesoporous titania nanostructures are exposed to water or need to be backfilled via infiltration with an aqueous solution, which can cause deformations of the nanostructure by capillary forces. In this work, the degree of deformation caused by water infiltration in two types of mesoporous, nanostructured titania films exposed to water vapor is compared. The different types of nanostructured titania films are prepared via a polymer template assisted sol-gel synthesis in conjunction with a polymer-template removal at high-temperatures under ambient conditions versus nitrogen atmosphere. Information about surface and inner morphology is extracted by scanning electron microscopy and grazing incidence small-angle neutron scattering (GISANS) measurements, respectively. Furthermore, complementary information on thin film composition and porosity are probed via X-ray reflectivity. The backfilling induced deformation of near surface structures and structures inside the mesoporous titania films is determined by GISANS before and after D O infiltration. The respective atmosphere used for template removal influences the details of the titania nanostructure and strongly impacts the degree of water induced deformation. Drying of the films shows reversibility of the deformation.

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Small Angle Scattering Techniques for the Study of Catalysts and Catalytic Processes

et al. 2023

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Small‐Angle Scattering (SAS) techniques are essential tools for the characterization of catalysts before, during and after catalytic reactions. Either based on X‐Rays (SAXS) or neutrons (SANS), they provide unique structural information that helps to understand catalytic processes at the nanoscale level, allowing a rational improvement of the catalysts design. In this review, we present the key aspects involved in the use of these techniques in the catalysis field. Firstly, we introduce some of the fundamentals of the techniques and describe their main features and their impact in the catalyst design. Then, we analyze key examples of the use of SAS to study catalysts’ structure through ex situ analysis, focusing on examples involving different porous materials and metallic nanoparticles. Afterwards, we discuss in situ and operando approaches for studying catalytical processes monitored using SAS. Finally, we present perspectives and challenges for the future use of SAS in the catalysis field.

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Grazing-incident neutron scattering to access catalyst for polymer electrolyte fuel cell

Cited by 15 publications

References 4 publications

Microstructure and water distribution in catalysts for polymer electrolyte fuel cells, elucidated by contrast variation small-angle neutron scattering

Microstructure and water distribution in catalysts for polymer electrolyte fuel cells, elucidated by contrast variation small-angle neutron scattering

Deformation of Mesoporous Titania Nanostructures in Contact with D₂O Vapor

Small Angle Scattering Techniques for the Study of Catalysts and Catalytic Processes

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Grazing-incident neutron scattering to access catalyst for polymer electrolyte fuel cell

Cited by 15 publications

References 4 publications

Microstructure and water distribution in catalysts for polymer electrolyte fuel cells, elucidated by contrast variation small-angle neutron scattering

Microstructure and water distribution in catalysts for polymer electrolyte fuel cells, elucidated by contrast variation small-angle neutron scattering

Deformation of Mesoporous Titania Nanostructures in Contact with D2O Vapor

Small Angle Scattering Techniques for the Study of Catalysts and Catalytic Processes

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Product

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Deformation of Mesoporous Titania Nanostructures in Contact with D₂O Vapor