Surfaces, Interfaces, and Applications
- Siddharth Rajupet
Siddharth Rajupet
Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States
Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
More by Siddharth Rajupet
- Adam Z. Weber*
Adam Z. Weber
Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
*E-mail: [emailprotected]
More by Adam Z. Weber
- Clayton J. Radke*
Clayton J. Radke
Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States
*E-mail: [emailprotected]
More by Clayton J. Radke
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ACS Applied Materials & Interfaces
Cite this: ACS Appl. Mater. Interfaces 2025, XXXX, XXX, XXX-XXX
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https://pubs.acs.org/doi/10.1021/acsami.5c00211
Published April 28, 2025
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Catalyst inks used to make fuel-cell electrodes consist of Pt/C catalyst particles and a perfluorosulfonic acid (PFSA) ionomer dispersed in water/alcohol solvent mixtures. PFSA ionomer in the ink adsorbs to the surface of the catalyst particles, dictating the dispersion colloid properties. Following adsorption, the subsequent distribution of excess nonadsorbed ionomer in the ink then governs the final structure of the electrode. Here, we characterize the adsorption of the PFSA ionomer onto Pt/C catalyst particles. PFSA adsorption is largely irreversible. Adsorbed sulfonic-acid moieties impart a negative charge on the catalyst surface, causing electrostatic repulsion between the free ionomer in solution and the ionomer-covered Pt/C particle surface. The amount of adsorption is limited by the resulting electrostatic charge that grows as more ionomer adsorbs, and the catalyst surface becomes more negatively charged. Attenuating electrostatic repulsion by increasing the ink ionic strength promotes ionomer adsorption. Electrostatically limited adsorption is observed, irrespective of the solvent water/n-propanol ratio or the catalyst particle porosity and Pt loading. Experimentally measured ionomer adsorption isotherms are well predicted by a Smoluchowski-based kinetic adsorption model, in which the electrostatic energy barrier for adsorption is predicted from DLVO theory. These findings help to unravel the complex phenomena within these colloidal dispersions, allowing for subsequent tailoring of inks to optimize fuel-cell electrode structure and performance.
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© 2025 American Chemical Society
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- Adsorption
- Catalysts
- Electrostatics
- Ionomers
- Solvents
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ACS Applied Materials & Interfaces
Cite this: ACS Appl. Mater. Interfaces 2025, XXXX, XXX, XXX-XXX
Click to copy citationCitation copied!
Published April 28, 2025
Publication History
Received
Accepted
Revised
Published
online
© 2025 American Chemical Society
Request reuse permissions
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