Inherent Acidity of Perfluorosulfonic Acid Ionomer Dispersions and Implications for Ink Aggregation
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Perfluorosulfonic acid (PFSA) dispersions are used as components in a variety of electrochemical technologies, particularly in fuel-cell catalyst-layer inks. In this study, we characterize dispersions of a common PFSA, Nafion, as well as inks of Nafion and carbon. It is shown that solvent choice affects a dispersion's measured pH, which is found to scale linearly with Nafion loading. Dispersions in water-rich solvents are more acidic than those in propanol-rich solvents: a 90% water versus 30% water dispersion can have up to a 55% measured proton deviation. Furthermore, because electrostatic interactions are a function of pH, these differences affect how particles aggregate in solution. Despite having different water contents, all inks studied demonstrate the same particle size and surface charge trends as a function of pH, thus providing insights into the relative influence of solvent and pH effects on these properties.
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Because the main chain and side chain are incompatible, solvents with different dielectric constant and solubility parameter have different compatibility with the main chain and side chain, resulting in ionomer agglomerates with different morphology, size, and conformation.
“Since the main chain and side chain are incompatible, the solvents with different dielectric constant and solubility parameter have different compatibility with the main chain and side chain, resulting in the ionomer agglomerates with different morphology, size, and conformation [26,32,134].”
From Effect of Catalyst Ink and Formation Process on the Multiscale Structure of Catalyst Layers in PEM Fuel Cells (2022) · cites this paper as [32]
Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.
Experimental — accuracy not yet measuredIf the solvent has excellent compatibility with the main chain, e.g., dipropylene glycol, the main chains tend to be extended out, and the Nafion ionomer commonly appears well dispersed, e.g., decreased ionomer agglomerate size or approaching solution behavior.
“If the solvent has excellent compatibility with the main chain, e.g., dipropylene glycol [23], the main chains tend to be extended out, and the Nafion ionomer commonly appears to be well dispersed, e.g., the decreased ionomer agglomerate size or approaching solution behavior [32,128].”
From Effect of Catalyst Ink and Formation Process on the Multiscale Structure of Catalyst Layers in PEM Fuel Cells (2022) · cites this paper as [32]
Split into 2 atoms — 0 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 1 unverifiable. Expand the claim to see per-atom verdicts.
Experimental — accuracy not yet measuredIonomer agglomerate morphology, size, and conformation differ with water fraction or type of alcohol, altering CL structure and performance.
“The morphology, size, and conformation of the ionomer agglomerates dispersed will differ with the water fraction or the type of alcohol, altering the CLs' structure and their performance [25,30,32,49,57,131,137,140].”
From Effect of Catalyst Ink and Formation Process on the Multiscale Structure of Catalyst Layers in PEM Fuel Cells (2022) · cites this paper as [32]
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“Due to the high affinity with water molecules, the side chains of Nafion tend to be extended out in the waterrich solvent mixtures, which would increase the coulomb repulsion force between Nafion agglomerates, or between catalyst–Nafion agglomerates, or between both, enhancing the colloidal stability of the ink, where…”
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- Authors
- Berlinger, S. A., McCloskey, B. D., & Weber, A. Z.
- Affiliations
- Lawrence Berkeley National Laboratory (US)
- Corresponding author
- Weber, Adam Z.
- Venue
- The Journal of Physical Chemistry B
- Publisher
- American Chemical Society (ACS)
- Published
- 2018-07-18
- Volume
- 122
- Issue
- 31
- Pages
- 7790-7796
- ISSN
- 1520-5207 (ISSN-L)
- 1520-6106
- OpenAlex
- W2884104828
- Cited by
- 122
- References
- 50
- Citations by year
- 2026: 16 · 2025: 19 · 2024: 17 · 2023: 13 · 2022: 15 · 2021: 17 · 2020: 16 · 2019: 8 · 2018: 1
- FWCI
- 4.02
- Type
- journal article
- Language
- en
- Open access
- green
- www.osti.gov
- Locations
- The Journal of Physical Chemistry B (publishedVersion)
- PubMed (publishedVersion)
- OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) (submittedVersion)
- eScholarship (California Digital Library) (submittedVersion)
- Funders
- Division of Graduate Education (DGE 1106400)
- Fuel Cell Technologies Office (DE-AC02-05CH11231)
- Topics
- Physical Sciences › Engineering › Electrical and Electronic Engineering › Fuel Cells and Related Materials
- Physical Sciences › Chemistry › Physical and Theoretical Chemistry › Electrostatics and Colloid Interactions
- Physical Sciences › Energy › Renewable Energy, Sustainability and the Environment › Electrocatalysts for Energy Conversion
- Keywords
- perfluorosulfonic acid ionomer, Nafion, ionomer dispersion, pH measurement, solvent effects, carbon-based ink, fuel cell catalyst layers, electrostatic interactions, surface charge, particle size
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