Does power ultrasound affect Nafion® dispersions?

Adamski, Michael; Peressin, Nicolas; Holdcroft, Steven; Pollet, Bruno G.

doi:10.1016/j.ultsonch.2019.104758

“…Similar results have previously been reported using Nafion® dispersions of differing concentrations (10, 5, and 2.5 wt%) [17] . Whereas ultrasonication in an ultrasonication bath for 60 min reduced the viscosity of Nafion® dispersions by up to 10.4 ± 1.8%, prolonged rapid stirring (1,000 RPM for 24 h) yielded negligible changes – a maximum decrease in viscosity of 2.3 ± 1.0% [17] . These data suggest that the use of rapid stirring, instead of ultrasound, is a viable means of dispersing the polymer solutions without inducing reductions in solution viscosity.…”

Section: Resultssupporting

confidence: 90%

“…Researchers in a typical academic research laboratory investigating the fabrication of MEAs for fuel cell and water electrolyzer applications often employ ultrasound during catalyst ink preparation (dispersion), yet, the effect of ultrasound on components of the ink, particularly the ionomer, is largely unknown [15] , [16] , [17] . This is surprising given the effects of power ultrasound (20 kHz – 2 MHz) in polymerization and depolymerization has been the subject of study for many years [18] , [19] , [20] , [21] , [22] , [23] .…”

Section: Introductionmentioning

confidence: 99%

“… [17] investigated the effect of power ultrasound on Nafion® dispersions, from which catalyst inks are typically prepared. The viscosity of Nafion® dispersions decreased with increasing ultrasonication time, potentially due to gradual, stepwise depolymerisation (degradation) of the ionomer [17] . Similar observations were previously described by Momand [37] , of the Pollet research group (University of Birmingham, UK) in 2013.…”

Section: Introductionmentioning

confidence: 99%

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Does power ultrasound affect hydrocarbon Ionomers?

Adamski

¹

,

Peressin

²

,

Balogun

³

et al. 2021

Ultrasonics Sonochemistry

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“…Similar observations have been reported by several research groups. For example, Adamski et al [71] systematically studied the effects of power ultrasound on Nafion® dispersion properties. The results showed a significant reduction in the viscosity of Nafion® on ultrasonication.…”

Section: Handling Properties Using Rheological Characterizationmentioning

confidence: 99%

On the State and Stability of Fuel Cell Catalyst Inks

Bapat

¹

,

Giehl²,

Kohsakowski³

et al. 2021

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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.

show abstract

“…Similar observations have been discussed in a few reports. For example, Adamski et al [70] systematically studied the effects of power ultrasound on Nafion® dispersion properties.…”

Section: Handling Properties Using Rheological Characterizationmentioning

confidence: 99%

On the State and Stability of Fuel Cell Catalyst Inks

Bapat¹,

Giehl²,

Kohsakowski³

et al. 2020

Preprint

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

Does power ultrasound affect Nafion® dispersions?

Cited by 29 publications

References 29 publications

Does power ultrasound affect hydrocarbon Ionomers?

Does power ultrasound affect hydrocarbon Ionomers?

On the State and Stability of Fuel Cell Catalyst Inks

On the State and Stability of Fuel Cell Catalyst Inks

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