A M-N<sub>3</sub>/C Active Site Prepared through Terpyridine Motifs (M= Fe, Co, Mn, Ni, Sn) for the Oxygen Reduction Reaction
Bibliographic record
Abstract
Non-noble catalysts for the oxygen reduction reaction (ORR) are in high demand for fuel cell technology due to their use of low cost and widely available starting materials. The development of these catalysts has been a constantly growing area. However, to the extent of our knowledge, there have only been a few literature reports that provide insights into the nature of the structure and geometry of the catalytically active sites formed in these materials. In the current literature, the most commonly proposed catalytically active site(s) for ORR are active sites that correspond to Fe-N2+2/C geometry. These active sites are typically produced through a high-temperature pyrolysis step to obtain this desired configuration[1]. However, the pyrolysis step is very disadvantageous due to the production of a variety of nitrogen functional groups on the surface which can negatively affect the activity of the catalyst, since only nitrogen functionalities with specified geometry are considered to be the most active for ORR[2,3]. In addition, high-temperature treatments drastically increases the overall cost of production and can be quite energy demanding. Thus, high-temperature treatment makes it difficult to design a surface rich in a specific active site for the desired application. We had previously developed a model of a catalyst rich in Fe-N3/C sites on a commercial Vulcan carbon. We showed that this site had high activity for the ORR reaction achieved by covalently functionalizing a carbon support with a nitrogen-rich terpyridine (tpy) ligand. The ligand geometry allowed for the formation of well-defined active sites on the carbon surface, leaving exposed N3 moities for the ORR. Metal-ligand coordination with Fe resulted in desired Fe-N3/C moieties on the surface. We demonstrated that this system can be prepared using mild reaction conditions and does not require high-temperature treatment for improved activity. On the contrary, the heat-treatment to this system was detrimental to the activity. Recently, we have been investigating the effect of other non-precious late transition metals for the activity of the novel N3/C sites. We present here the results of the M-N3/C site where M= Co, Sn, Ni, or Mn and show that these metals also show promising electrochemical activity in both acidic and basic media due to well-defined N3/C site for the ORR, showing generality of our initial results with iron and overall versatility and activity of an N3 site in combination with various non-precious metals for an ORR catalyst. [1] M. Lefèvre, E. Proietti, F. Jaouen, J.-P. Dodelet, Science 2009, 324, 71-74. [2] F. Charreteur, F. Jaouen, S. Ruggeri, J.-P. Dodelet, Electrochimica acta 2008, 53, 2925-2938. [3] H. M. Fruehwald, I. I. Ebralidze, O. V. Zenkina, E. B. Easton, ChemElectroChem 2019, 6, 1350. Figure 1
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".