Durability of hydrocarbon ionomer-based cathode catalyst layers for PEM fuel cells under voltage cycling
Bibliographic record
Abstract
Hydrocarbon (HC)-based proton-exchange membrane fuel cells have gained attention as a more sustainable alternative to conventional systems utilizing perfluorosulfonic acid (PFSA). While current optimizations have revealed performance parity of sulfo-phenylated poly(phenylene) ionomers in cathode catalyst layers (CLs), the long-term durability of CLs employing such HC ionomers remains insufficiently characterized. By applying a voltage cycling accelerated stress test (AST), this study finds a higher cathode CL degradation compared to a PFSA-based reference in a twofold sense: First, the CL's protonic resistance increases during the AST, which is not observed in the PFSA case. Second, the catalyst roughness factor decreases faster due to an accelerated Pt nanoparticle growth. While this decay of electrochemically active surface area scales expectedly with ionic conductivity (i.e., with ionomer volume fraction and relative humidity) within the same ionomer class, it is surprisingly found that even at a lower absolute number of sulfonic acid groups and lower ionic conductivity, the HC-based CL undergoes faster Pt agglomeration than the PFSA counterpart. As a speculative explanation, first evidence of a higher affinity of the utilized HC ionomer towards Pt ions is revealed, which may lead to an increased Pt content within the ionomer and hence to an enhanced ionic Pt transport.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".