Tuning the photocatalytic activity of titanium dioxide by encapsulation inside zeolites exemplified by the cases of thianthrene photooxygenation and horseradish peroxidase photodeactivation
Bibliographic record
Abstract
A series of Y, Beta, mordenite and ZSM-5 zeolites containing different amounts of nanosized TiO2 clusters have been prepared by TiO2+ exchange followed by condensation. The presence of TiO2+ and its subsequent oligomerization can be followed in Raman spectroscopy by the appearance of the band at ca. 530 cm−1 and its replacement by others at 394, 460 and 637 nm. X-ray diffractograms of the solids show a considerable intensity decrease as the amount of TiO2 present increases. High-resolution transmission electron microscopy (HRTEM) shows that no isolated TiO2 particles are present in the case of zeolite Y, while the sample of mordenite at the highest Ti loading contains isolated TiO2 particles distinguishable by HRTEM. Diffuse reflectance UV-Vis spectroscopy indicates that the bandgap and the apparent extinction coefficient depend remarkably on the Ti content as well as on the zeolite crystal structure. Quantum chemical calculations at the semiempirical level also predict large variations in the HOMO–LUMO energies as a function of the number of Ti atoms. It has been found that the photoactivity of TiO2@Y and TiO2@mordenite is higher than that of commercial anatase for the photooxygenation of thianthrene to thianthrene oxide (λex > 200 nm), but smaller for the hoseradish peroxidase photodeactivation in aqueous buffer (λex = 350 nm). These variations in the photocatalytic activity of TiO2 illustrate the potential that inclusion of TiO2 nanoclusters within zeolites has to modulate its photoactivity.
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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".