Preparation procedure for the electrode slurries of polymer electrolyte fuel cells utilizing the irreversibility of ionomer adsorption onto Pt–C particles

Kishi, Michito; Tanaka, Masaki; Mori, Takamasa

doi:10.2109/jcersj2.19152

Cited by 11 publications

(4 citation statements)

References 31 publications

(26 reference statements)

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“…Recently, a few groups intensively attempted to control the microstructure of CLs by adding alcohols in catalyst inks. − Takahashi et al investigated the influence of the microstructure of CLs tuned by using mixed solutions of 1-propanol and water on the cell performance through the structural observation by cryo-SEM and laser diffraction coupled with qualitative electrochemical analysis . They found that catalyst inks prepared in three different solutions with different water/1-propanol ratios result in the formation of differently sized agglomerates of the Pt/C electrocatalysts interconnected by ionomers; cross-sectional cryo-SEM images indicated that larger agglomerates and pores were formed in CLs prepared from a water-rich solution, than those from an alcohol-rich solution.…”

Section: Introductionmentioning

confidence: 61%

Solvent-Dependent Adsorption of Perfluorosulfonated Ionomers on a Pt(111) Surface Using Atomic Force Microscopy

Devivaraprasad

Masuda

2020

Langmuir

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The adsorption behavior of perfluorosulfonated ionomers (PFSIs) on a Pt(111) surface in various solvents is investigated by in situ atomic force microscopy (AFM) and discussed on the basis of aggregation of PFSIs in the liquid phase. The AFM images show that, in an aqueous solution of PFSI (0.1 wt % Nafion + 99.9 wt % water), PFSI aggregates with a lateral size of 20−200 nm adsorb on the Pt(111) surface. In a PFSI solution containing a small amount of 1-propanol (0.1 wt % Nafion + 99.5 wt % water + 0.4 wt % 1-propanol), however, slightly smaller aggregates adsorb on the Pt(111) surface. Such solvent-dependent sizes of adsorbed aggregates are in reasonable agreement with apparent hydrodynamic radii of PFSIs in the corresponding solutions determined by dynamic light scattering (DLS) while assuming the formation of spherical aggregation. Interestingly, a step-terrace structure characteristic to a clean Pt(111) surface is observed in a propanol-rich PFSI solution (0.1 wt % Nafion + 44.45 wt % water + 55.45 wt % 1-propanol) but X-ray photoelectron spectroscopy clearly indicates the existence of fluorocarbon species at the Pt(111) surface, suggesting the formation of a smooth adsorbed layer of PFSIs in a lying down configuration. Absence of any features assignable to aggregates in DLS data suggests well-dispersion of PFSIs in such propanol-rich solution without aggregations. Thus, the adsorbed structure of PFSIs at Pt surfaces can be controlled by tuning the composition of mixed solvent, which affects the aggregation of PFSI in the liquid phase.

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Section: Introductionmentioning

confidence: 61%

Solvent-Dependent Adsorption of Perfluorosulfonated Ionomers on a Pt(111) Surface Using Atomic Force Microscopy

Devivaraprasad

Masuda

2020

Langmuir

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“…15 Thus, the investigation of the ink sedimentation dynamics provides additional information for understanding the solvent-dependent ink structure dynamics. In this study, the AC approach using a 29 700 EW PFSA ionomer in NPA/Water (half blue triangle, 0.32 mg ml −1 ), 6 Nafion DE1021 in EtOH/Water (half green diamond, 50-53 mg ml −1 ), 30 Nafion D521 in DPG/Water (open pink diamond, ∼10 mg ml −1 ), 7 Aquivion PW79S in DPG/Water (half orange star, ∼10 mg ml −1 ). 31 (e) Comparison of the PSDs of catalyst dispersions: Pt/C in NPA/Water (black circle, 9.24 wt%, this work), Vulcan carbon in NPA (red square cross, 0.1 wt%), 16 Vulcan carbon in NPA/Water (blue triangle cross, 0.1 wt%), 32 and Fe-N-C PGM-free in NPA/Water (open orange pentagon, 5 wt%).…”

Section: Resultsmentioning

confidence: 99%

Characterization of Solvent-Dependent Ink Structure and Catalyst Layer Morphology Based on Ink Sedimentation Dynamics and Catalyst-Ionomer Cast Films

Taning

Lee

Woo

et al. 2021

J. Electrochem. Soc.

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Ink structure is of great research interest because it influences the catalyst layer microstructure and ultimately determines fuel cell performance. To improve understanding of the ink structure, particle size distribution and ink sedimentation dynamics were characterized in this study by performing acoustic spectroscopy (AS) and analytical centrifugation (AC) analyses, respectively, using actual concentrations of Pt/C inks (10.4 wt% of solid content) without dilution. For the catalyst inks prepared with 1-propanol-water bi-solvents of different compositions, the particle size distributions of the inks were similar when a small amount of ionomer (I/C 0.2) was included in the ink. However, the ink sedimentation dynamics showed significantly different results depending on the solvent composition. The different ink dynamics can be explained in terms of the ink structure, and these solventdependent ink structures were further studied through the fabrication of catalyst-ionomer cast films. The catalyst agglomeration size and the catalyst-ionomer interfacial structure were effectively observed using scanning electron microscopy (SEM) images obtained from the cast films. The present study reveals the effects of the solvent properties on the structures of ink and catalyst agglomerates. It also demonstrates that the AS and AC techniques can be useful for ink studies.

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“…Numerous research groups have explored the impact of solvents with varying dielectric constants such as npropanol, [9c] dipropylene glycol, [44] water/propanol, [45] and water/ethanol. [46] Variations in solvent dielectric constants can induce distinct ionomer morphologies in solutions, consequently affecting ionomer microstructures within the electrode. These structures can manifest in three forms based on the dielectric constant: precipitation (for dielectric constants < 3), colloidal dispersion (for dielectric constants between 3 and 10), and dissolution (for dielectric constants > 10).…”

Section: Electrode Ink Formulationmentioning

confidence: 99%

“…The state of ionomers in inks is closely linked to the interactions between ionomers and solvents. Numerous research groups have explored the impact of solvents with varying dielectric constants such as n‐propanol, [9c] dipropylene glycol, [44] water/propanol, [45] and water/ethanol [46] . Variations in solvent dielectric constants can induce distinct ionomer morphologies in solutions, consequently affecting ionomer microstructures within the electrode.…”

Section: Meso/macro Scale Analysismentioning

confidence: 99%

Investigating Electrode‐Ionomer Interface Phenomena for Electrochemical Energy Applications

Jo,

Kim,

Park

et al. 2024

Chemistry An Asian Journal

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The endeavor to develop high‐performance electrochemical energy applications has underscored the growing importance of comprehending the intricate dynamics within an electrode's structure and their influence on overall performance. This review investigates the complexities of electrode‐ionomer interactions, which play a critical role in optimizing electrochemical reactions. Our examination encompasses both microscopic and meso/macro scale functions of ionomers at the electrode‐ionomer interface, providing a thorough analysis of how these interactions can either enhance or impede surface reactions. Furthermore, this review explores the broader‐scale implications of ionomer distribution within porous electrodes, taking into account factors like ionomer types, electrode ink formulation, and carbon support interactions. We also present and evaluate state‐of‐the‐art techniques for investigating ionomer distribution, including electrochemical methods, imaging, modeling, and analytical techniques. Finally, the performance implications of these phenomena are discussed in the context of energy conversion devices. Through this comprehensive exploration of intricate interactions, this review contributes to the ongoing advancements in the field of energy research, ultimately facilitating the design and development of more efficient and sustainable energy devices.

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Preparation procedure for the electrode slurries of polymer electrolyte fuel cells utilizing the irreversibility of ionomer adsorption onto Pt–C particles

Cited by 11 publications

References 31 publications

Solvent-Dependent Adsorption of Perfluorosulfonated Ionomers on a Pt(111) Surface Using Atomic Force Microscopy

Solvent-Dependent Adsorption of Perfluorosulfonated Ionomers on a Pt(111) Surface Using Atomic Force Microscopy

Characterization of Solvent-Dependent Ink Structure and Catalyst Layer Morphology Based on Ink Sedimentation Dynamics and Catalyst-Ionomer Cast Films

Investigating Electrode‐Ionomer Interface Phenomena for Electrochemical Energy Applications

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