Nitrogen Doping Effects on Carbon Nanotubes and the Origin of the Enhanced Electrocatalytic Activity of Supported Pt for Proton-Exchange Membrane Fuel Cells
Bibliographic record
Abstract
Carbon nanotubes (CNTs) and nitrogen-doped carbon nanotubes (CNx) were synthesized by the floating catalyst chemical vapor deposition (FCCVD) method. Pt nanoparticles were deposited onto the two catalyst supports with the ethylene glycol reduction method. Different from CNTs that contain straight hollow tubes, CNx contain a bamboolike structure with kinks along the tubes and more surface defects. X-ray photoelectron spectroscopy (XPS) confirms the nitrogen atoms in the graphite matrix and reveals the chemical natures of the doped nitrogen atoms. Carbon K-edge near-edge X-ray absorption fine structure (NEXAFS) and Raman characterizations reveal higher defectiveness in CNx than CNTs. The unique structure and surface property of CNx leads to a better dispersion of Pt nanoparticles on CNx than on CNTs, as revealed by TEM images. Pt supported on CNx (Pt/CNx) exhibited a higher electrochemical surface area (ECSA) and higher catalytic activity toward oxygen reduction reaction (ORR), in comparison to Pt supported on CNTs (Pt/CNTs). Better performance of Pt/CNx than Pt/CNTs has been confirmed by single-cell fuel cell tests.
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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 | 0.001 |
| 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 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".