Overcoming the Challenges of Beam-sensitivity in Fuel Cell Electrodes

Cullen, David A.; Sneed, Brian T.; More, Karren L.

doi:10.1017/s1431927617011771

Cited by 2 publications

(2 citation statements)

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“…The location of the nanosized metallic catalysts on the carbon supports was previously successfully imaged using electron tomography in a transmission electron microscopy (TEM) or scanning TEM (STEM) mode [4][5][6][7] . Electron tomography is an inherently dose-intensive technique and thus these studies omitted information on the extremely electron-beam-sensitive ionomer phase [8][9][10] . The poor contrast between the ionomer and carbon support 11,12 also makes quantitative analysis a challenging computer vision problem.…”

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confidence: 99%

Three-dimensional nanoimaging of fuel cell catalyst layers

et al. 2023

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Catalyst layers in proton exchange membrane fuel cells consist of platinum-group-metal nanocatalysts supported on carbon aggregates, forming a porous structure through which an ionomer network percolates. The local structural character of these heterogeneous assemblies is directly linked to the mass-transport resistances and subsequent cell performance losses; its three-dimensional visualization is therefore of interest. Herein we implement deep-learning-aided cryogenic transmission electron tomography for image restoration, and we quantitatively investigate the full morphology of various catalyst layers at the local-reaction-site scale. The analysis enables computation of metrics such as the ionomer morphology, coverage and homogeneity, location of platinum on the carbon supports, and platinum accessibility to the ionomer network, with the results directly compared and validated with experimental measurements. We expect that our findings and methodology for evaluating catalyst layer architectures will contribute towards linking the morphology to transport properties and overall fuel cell performance.

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confidence: 99%

Three-dimensional nanoimaging of fuel cell catalyst layers

et al. 2023

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“…Additional control experiments were performed to ensure that the modified chemistry at the Pt/PFSA interface was not an artifact of the X-ray beam. PFSA has been shown to be extremely sensitive to electron beam and X-ray damage. , The methodology used here has been optimized to minimize this damage, including low-dose collection strategies, quantitative dosimetry, and appropriate data processing . These precautions allow for STXM imaging of catalyst layer samples at high spatial resolution, near the limits of current instrumentation.…”

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confidence: 99%

Imaging Reactivity of the Pt–Ionomer Interface in Fuel-Cell Catalyst Layers

et al. 2020

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The interface between perfluorosulfonic acid polymer electrolytes and Pt nanoparticles in a model hydrogen fuel-cell catalyst layer was analyzed using high-resolution scanning transmission X-ray microscopy. After electrochemical cycling, thin films of damaged ionomer, enriched in CC bonds, are observed near the Pt surface. This local degradation of the Pt–ionomer interface triggered by electrochemical oxidation contrasts with that from peroxide radical exposure. Peroxide damage is catalyzed by Pt and leads instead to thin films containing carboxylic acids. Direct mapping of the degradation at these nanoscale interfaces inside hydrogen fuel-cell catalyst layers exposes a previously unknown electrochemical reactivity of perfluorinated ionomers.

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Overcoming the Challenges of Beam-sensitivity in Fuel Cell Electrodes

Cited by 2 publications

References 5 publications

Three-dimensional nanoimaging of fuel cell catalyst layers

Three-dimensional nanoimaging of fuel cell catalyst layers

Imaging Reactivity of the Pt–Ionomer Interface in Fuel-Cell Catalyst Layers

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