X-ray transparent proton-exchange membrane fuel cell design for in situ wide and small angle scattering tomography

Martens, Isaac; Vamvakeros, Antonis; Chattot, Raphaël; Blanco, María Valeria; Rasola, Miika; Pusa, Janne; Jacques, Simon D. M.; Bizzotto, Dan; Wilkinson, David P.; Ruffmann, B.; Heidemann, Stefan; Honkimäki, V.; Drnec, Jakub

doi:10.1016/j.jpowsour.2019.226906

Cited by 45 publications

(43 citation statements)

References 41 publications

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“…lattice parameter, peak widths). 35 Here we disclose a new tomographic algorithm called Direct Least-Squares Reconstruction (DLSR) which provides a generalized solution to this problem, and corrects for parallax distortion in arbitrarily large samples. Therefore, the practical maximum sample size for XRD-CT is limited only by penetration of the X-ray beam.…”

Section: Degradation After a Potentiostatic Hold At 1 Vmentioning

confidence: 99%

Imaging Heterogeneous Electrocatalyst Stability and Decoupling Degradation Mechanisms in Operating Hydrogen Fuel Cells

et al. 2021

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Proliferation of hydrogen fuel cell systems is hindered by degradation of the platinum catalyst.Here, we provide a device level assessment of the catalyst degradation phenomena and its coupling to nanoscale hydration gradients, using advanced operando X-ray scattering tomography tailored for device-scale imaging. Gradients formed inside the fuel cell produce heterogeneous degradation of the catalyst nanostructure, which can be linked to the flow field design and water distribution in the cell. Striking differences in catalyst degradation are observed between operating fuel cell devices and the liquid cell routinely used for catalyst stability studies, highlighting the crucial impact of the complex operating environment on the catalyst degradation phenomena. This degradation knowledge gap accentuates the necessity of multimodal, in situ characterization of real devices when assessing the performance and durability of electrocatalysts, and more generally, electrochemically active phases used in energy conversion and storage technologies.

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Section: Degradation After a Potentiostatic Hold At 1 Vmentioning

confidence: 99%

Imaging Heterogeneous Electrocatalyst Stability and Decoupling Degradation Mechanisms in Operating Hydrogen Fuel Cells

et al. 2021

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“…From an angular range of six 2θ onwards, the platinum reflections are virtually free of background and can readily be analyzed by Rietveld refinement. 45 Simultaneously varying both the fraction and crystallite size of the two populations of Pt NPs in the Rietveld refinement of WAXS data was not feasible due to the intertwining of these variables, as only one population with an average coherent domain size was obtained. Therefore, we used the mean particle size of the two populations derived by the SAXS fitting as pre-defined input values in the Rietveld refinement of the WAXS data.…”

Section: Resultsmentioning

confidence: 99%

“…To induce and uncover electrochemical Ostwald ripening, i.e., the growth of larger NPs at the expense of smaller ones, a bimodal Pt/C catalyst obtained by mixing two different commercial Pt/C catalysts with distinguishable size populations, was studied, see Figure 1. The here applied grazing-incidence mode allows a straightforward selection not only of different spots at the same depth (same x-y planes) in the catalyst layer, but additionally z-scans can be performed 45 to investigate if the degradation depends on the distance of the NPs to the electrolyte-catalyst interface, see Figure S1 for a scheme of the x-, y-, z-directions relative to the electrolyte-catalyst interface.…”

Section: Wide-angle X-ray Scattering (Waxs)mentioning

confidence: 99%

Tracking the Catalyst Layer Depth-Dependent Electrochemical Degradation of a Bimodal Pt/C Fuel Cell Catalyst: A Combined Operando Small- and Wide-Angle X-Ray Scattering Study

Schröder

Pittkowski

Martens

et al. 2021

Preprint

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The combination of operando small- and wide-angle X-ray scattering (SAXS, WAXS) in grazing incidence configuration is presented as a new approach to provide depth-dependent insights into the changes in mean particle sizes and phase fractions occurring for fuel cell catalysts during accelerated stress tests (ASTs). As fuel cell catalyst, a bimodal Pt/C catalyst was chosen that consists of two distinguishable particle size populations. The presence of the two different sizes should favor and uncover electrochemical Ostwald ripening as the major degradation mechanism, i.e., it is expected that the size of the larger particles in the Pt/C catalyst grows at the expense of the smaller particles. The grazing incidence mode performed at the European Synchrotron Radiation Facility (ESRF) at the ID31 beamline revealed an intertwinement of the depth dependent degradation. While the larger particles show the same particle size changes close to the electrolyte-catalyst interface and within the catalyst layer, for the smaller Pt nanoparticles a different degradation scenario is observed. At the electrolyte-catalyst interface, the smaller particles increase in size while their phase fraction decreases during the AST. However, in the inner catalyst layer the phase fraction of smaller particles increases instead of decreases. The results of a depth-dependent degradation strongly suggest to employ a depth-dependent catalyst design for future improvement of the catalyst stability.

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“…X-ray diffraction computed tomography (XRD-CT) is a powerful characterisation technique which has been lately applied to study a variety of functional materials and devices including operating solid catalysts, fuel cells and batteries. [53][54][55][56][57][58][59][60][61][62][63][64] The radial distribution of the various crystalline catalyst components under operating conditions was investigated with the 3D-XRD-CT technique. In addition, the fast solidstate changes occurring along the catalyst bed were followed with X-ray diffraction mapping.…”

Section: Introductionmentioning

confidence: 99%

Multi-length scale 5D diffraction imaging of Ni–Pd/CeO₂–ZrO₂/Al₂O₃ catalyst during partial oxidation of methane

Matras

Vamvakeros

Jacques³

et al. 2021

J. Mater. Chem. A

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X-ray transparent proton-exchange membrane fuel cell design for in situ wide and small angle scattering tomography

Cited by 45 publications

References 41 publications

Imaging Heterogeneous Electrocatalyst Stability and Decoupling Degradation Mechanisms in Operating Hydrogen Fuel Cells

Imaging Heterogeneous Electrocatalyst Stability and Decoupling Degradation Mechanisms in Operating Hydrogen Fuel Cells

Tracking the Catalyst Layer Depth-Dependent Electrochemical Degradation of a Bimodal Pt/C Fuel Cell Catalyst: A Combined Operando Small- and Wide-Angle X-Ray Scattering Study

Multi-length scale 5D diffraction imaging of Ni–Pd/CeO₂–ZrO₂/Al₂O₃ catalyst during partial oxidation of methane

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X-ray transparent proton-exchange membrane fuel cell design for in situ wide and small angle scattering tomography

Cited by 45 publications

References 41 publications

Imaging Heterogeneous Electrocatalyst Stability and Decoupling Degradation Mechanisms in Operating Hydrogen Fuel Cells

Imaging Heterogeneous Electrocatalyst Stability and Decoupling Degradation Mechanisms in Operating Hydrogen Fuel Cells

Tracking the Catalyst Layer Depth-Dependent Electrochemical Degradation of a Bimodal Pt/C Fuel Cell Catalyst: A Combined Operando Small- and Wide-Angle X-Ray Scattering Study

Multi-length scale 5D diffraction imaging of Ni–Pd/CeO2–ZrO2/Al2O3 catalyst during partial oxidation of methane

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Multi-length scale 5D diffraction imaging of Ni–Pd/CeO₂–ZrO₂/Al₂O₃ catalyst during partial oxidation of methane