Supported Vanadium Oxide Clusters in Partial Oxidation Processes: Catalytic Consequences of Size and Electronic Structure
Bibliographic record
Abstract
Abstract The catalytic activity for ethanol partial oxidation of vanadium oxide (VOx) anchored on titanium oxide was correlated to their electronic structure. In situ Raman spectroscopy and temperature‐programmed desorption (TPD) experiments indicate that the presence of catalytically active VOx moieties is very sensitive to vanadia loading: highly dispersed VOx predominantly exists at low VOx contents whereas larger vanadia clusters coexist at higher VOx loadings. In situ UV/Vis spectroscopy revealed that a significant fraction of these larger clusters remain reduced during catalysis, and thus do not fully participate in catalytic turnovers. The electronic structures of model VOx nanoclusters of different sizes (monomer, dimer, trimer, and one‐dimensional polymers) were investigated by using periodic density functional theoretical calculations. Results indicate that their electronic structures are significantly affected by their size. Our analysis also revealed that the formation of reduced VOx species (V4+) during catalysis is concomitant to the reduction of adjacent Ti cations (Ti3+). Theoretically calculated optical absorption spectra matched the experimental spectroscopic results obtained under in situ reaction conditions. Furthermore, the determination of defect formation enthalpies reported previously as the main descriptor for catalytic activity of vanadia nanoclusters, predicted that isolated monomeric VOx clusters predominantly take part in catalytic turnovers.
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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 | 0.000 | 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".