Tunable Composition Aqueous-Synthesized Mixed-Phase TiO2 Nanocrystals for Photo-Assisted Water Decontamination: Comparison of Anatase, Brookite and Rutile Photocatalysts
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Bibliographic record
Abstract
Mixed-phase nanoTiO2 materials attract a lot of attention as advanced photocatalysts for water decontamination due to their intrinsic structure that allows better photo-excited e−cb-h+vb charge separation, hence improved photocatalytic efficiency. Currently, the best-known mixed-phase TiO2 photocatalyst is P25 with approximate composition 80% Anatase/20% Rutile (A/r). Apart from Anatase (A) and Rutile (R) phases, there is Brookite (B) which has been evaluated less as photocatalyst in mixed-phase nanoTiO2 systems. In this work we present a sustainable solution process to synthesize tunable composition mixed-phase nanotitania photocatalysts in a continuously stirred tank reactor (CSTR) by modulating conditions like pH, CTiCl4 and time. In particular three mixed-phase TiO2 nanomaterials were produced, namely one predominantly anatase with brookite as minor component (A/b), one predominantly brookite with minor component rutile (B/r), and one predominantly rutile with minor component brookite (R/b) and evaluated as photocatalysts in the degradation of methyl orange. The three semiconducting nanomaterials were characterized by XRD and Raman spectroscopy to quantify the phase ratios and subjected to nano-morphological characterization by FE-SEM and TEM/HR-TEM. The new mixed-phase nanoTiO2 materials are shown to be endowed with large specific surface area, ranging from 90–125 m2 g−1, double of that of P25, to be mesoporous and be surface-rich in Ti–OH molecular groups varying from 12%–20% versus 4% for P25. These properties though impact the adsorptive capacity with R/b and B/r removing > 50% of MO but not photocatalytic activity. The latter depends on nanograined mixed-phase structure and not mere assembly of different phase nanoparticles. First-order rate constants reveal essentially equivalent photocatalytic activity for anatase nanocrystals with either rutile (P25) or brookite (this work) domains.
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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) | 0.001 | 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 it