O<sub>2</sub> Reduction in PEM Fuel Cells: Activity and Active Site Structural Information for Catalysts Obtained by the Pyrolysis at High Temperature of Fe Precursors
Bibliographic record
Abstract
Catalytic activity for O 2 electroreduction in acidic medium has been studied. Catalysts have been produced by pyrolyzing perylene tetracarboxylic dianhydride (PTCDA) combined with Fe and N precursors. The Fe precursors used in this work are either Fe II acetate or Cl−Fe III Tetramethoxyphenyl porphyrin (Cl−FeTMPP). The N precursors are NH 3 and/or Cl−FeTMPP. To be able to vary the catalytic activity, two synthesis procedures have been used, varying either the heat-treatment temperature or the Fe content of the pyrolyzed materials. All the catalysts have been studied by Time-of-Flight Secondary Ion Mass Spectrometry (ToF SIMS) in order to find out if the relative intensity of one or several secondary ions was following the changes observed in the catalytic activity. Only one ion, FeN 2 C 4 +, may be considered as the signature of the catalytic site generated in this work. It has been detected in all prepared catalysts, whatever the Fe precursor or the synthesis procedure was used. It is proposed that this ion is produced under ToF SIMS analysis from part of a 1,10 phenanthrolinic-type structure, which is itself part of the catalytic site. This catalytic site is probably the same as the one obtained by the pyrolysis at high temperature (≥ 800 °C) of N 4 −Fe macrocycles adsorbed on carbon black. RDE and PEM fuel cell tests demonstrate that the most performing catalysts are those containing 2 wt % Fe as Cl−FeTMPP and 0.2 wt % Fe as Fe acetate. Increasing the Fe content beyond these limits mainly generates catalytically inactive Fe clusters and interferes with the characterization of the high-temperature active site.
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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 | 0.000 | 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 | 0.001 |
| 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".