Sedimentation Dynamics of Colloidal Formulations through Direct Visualization: Implications for Fuel Cell Catalyst Inks

Bapat, Shalmali; Segets, Doris

doi:10.1021/acsanm.0c01467

“…In our previous work, as shown in Figure 1C, we demonstrated how the raw data acquired by AC can be transformed into intuitive visual formats called transmittograms [48]. Such an image is The ability to visualize the entire centrifugation experiment, while tracking several colloidal features, can be a powerful tool in the study of complex dispersions.…”

Section: Transmittogram Analysismentioning

confidence: 99%

“…They employed AC to study different I/C ratios, but final ink dispersions were prepared sans Pt. We have also begun to address the challenges in investigating inks and fill the gaps using AC by proposing a novel technique to evaluate the dispersion state using spatio-temporal maps, called transmittograms [48]. However, systematic evaluation of process-structure relations through a time-resolved assesment of ink behavior and stability, has not been explored to the best of our knowledge.…”

Section: Introductionmentioning

confidence: 99%

On the State and Stability of Fuel Cell Catalyst Inks

Bapat¹,

Giehl²,

Kohsakowski³

et al. 2020

Preprint

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Catalyst layers (CL) as an active component of the catalyst coated membrane (CCM) form the heart of proton electrolyte membrane fuel cells (PEMFC). For optimum performance of the fuel cell, obtaining suitable structural and functional characteristics for the CL is crucial. Direct tuning of the microstructure and morphology of the CL is non-trivial; hence catalyst inks as catalyst layer precursors need to be modulated, which are then applied onto a membrane, to form the CCM. Obtaining favorable dispersion characteristics forms an important prerequisite in engineering catalyst inks for large scale manufacturing. In order to facilitate a knowledge-based approach for developing fuel cell inks, this work introduces new tools and methods to study both the dispersion state and stability characteristics, simultaneously. Catalyst inks were prepared using different processing methods which include stirring and ultrasonication. The proposed tools are used to characterize and elucidate the effects of the processing method. Structural characterization of the dispersed particles and their assemblages was carried out by means of transmission electron microscopy. Analytical centrifugation (AC) was used to study the state and stability of inks. Herein, we introduce new concepts, S score and stability trajectory, for a time-resolved assessment of inks in their native state using AC. The findings were validated and rationalized using transmittograms as a direct visualization technique. The flowability of inks was investigated by rheological measurements. It was found that probe sonication only up to an optimum amplitude leads to a highly stable colloidal ink.

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“…In our previous work, as shown in Figure 1C, we demonstrate how the raw data acquired by AC can be transformed into intuitive visual formats called transmittograms [49]. Such an image is constructed by plotting a heatmap from all captured instantaneous transmission values over space across the sample cell and time.…”

Section: Transmittogram Analysismentioning

confidence: 99%

“…They employed AC to study different I/C ratios, but final ink dispersions were prepared sans Pt. We have also begun to address the challenges in investigating inks and fill the gaps using AC by proposing a novel technique to evaluate the dispersion state using spatio-temporal maps, called transmittograms [49]. However, systematic evaluation of process-structure relations through a time-resolved assesment of ink behavior and stability, has not been explored to the best of our knowledge.…”

Section: Introductionmentioning

confidence: 99%

On the State and Stability of Fuel Cell Catalyst Inks

Bapat

¹

,

Giehl²,

Kohsakowski³

et al. 2021

Preprint

Self Cite

0

View full text Add to dashboard Cite

Catalyst layers (CL) as an active component of the catalyst coated membrane (CCM) form the heart of proton electrolyte membrane fuel cells (PEMFC). For optimum performance of the fuel cell, obtaining suitable structural and functional characteristics for the CL is crucial. Direct tuning of the microstructure and morphology of the CL is non-trivial; hence catalyst inks as catalyst layer precursors need to be modulated, which are then applied onto a membrane, to form the CCM. Obtaining favorable dispersion characteristics forms an important prerequisite in engineering catalyst inks for large scale manufacturing. In order to facilitate a knowledge-based approach for developing fuel cell inks, this work introduces new tools and methods to study both the dispersion state and stability characteristics, simultaneously. Catalyst inks were prepared using different processing methods which include stirring and ultrasonication. The proposed tools are used to characterize and elucidate the effects of the processing method. Structural characterization of the dispersed particles and their assemblages was carried out by means of transmission electron microscopy. Analytical centrifugation (AC) was used to study the state and stability of inks. Herein, we introduce new concepts, S score and stability trajectory, for a time-resolved assessment of inks in their native state using AC. The findings were validated and rationalized using transmittograms as a direct visualization technique. The flowability of inks was investigated by rheological measurements. It was found that probe sonication only up to an optimum amplitude leads to a highly stable colloidal ink.

show abstract

“…In our previous work, as shown in Figure 1C, we demonstrated how the raw data acquired by AC can be transformed into intuitive visual formats called transmittograms [48]. Such an image is constructed by plotting a heatmap from all captured instantaneous transmission values over space across the sample cell and time.…”

Section: Transmittogram Analysismentioning

confidence: 99%

On the State and Stability of Fuel Cell Catalyst Inks

Bapat

¹

,

Giehl²,

Kohsakowski³

et al. 2021

Preprint

Self Cite

0

View full text Add to dashboard Cite

Catalyst layers (CL), as an active component of the catalyst coated membrane (CCM), form the heart of the proton electrolyte membrane fuel cell (PEMFC). For optimum performance of the fuel cell, obtaining suitable structural and functional characteristics for the CL is crucial. Direct tuning of the microstructure and morphology of the CL is non-trivial; hence catalyst inks as CL precursors need to be modulated, which are then applied onto a membrane to form the CCM. Obtaining favorable dispersion characteristics forms an important prerequisite in engineering catalyst inks for large scale manufacturing. In order to facilitate a knowledge-based approach for developing fuel cell inks, this work introduces new tools and methods to study both the dispersion state and stability characteristics, simultaneously. Catalyst inks were prepared using different processing methods, which include stirring and ultrasonication. The proposed tools are used to characterize and elucidate the effects of the processing method. Structural characterization of the dispersed particles and their assemblages was carried out by means of transmission electron microscopy. Analytical centrifugation (AC) was used to study the state and stability of the inks. Herein, we introduce new concepts, S score, and stability trajectory, for a time-resolved assessment of inks in their native state using AC. The findings were validated and rationalized using transmittograms as a direct visualization technique. The flowability of inks was investigated by rheological measurements. It was found that probe sonication only up to an optimum amplitude leads to a highly stable colloidal ink.

show abstract

Sedimentation Dynamics of Colloidal Formulations through Direct Visualization: Implications for Fuel Cell Catalyst Inks

Cited by 25 publications

References 31 publications

On the State and Stability of Fuel Cell Catalyst Inks

On the State and Stability of Fuel Cell Catalyst Inks

On the State and Stability of Fuel Cell Catalyst Inks

On the State and Stability of Fuel Cell Catalyst Inks

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