Effect of Transition Metal Ions on the TiO<sub>2</sub>-Assisted Photodegradation of Dyes under Visible Irradiation: A Probe for the Interfacial Electron Transfer Process and Reaction Mechanism
Bibliographic record
Abstract
The effect of metal ions (Cu 2+, Fe 3+, Zn 2+, Al 3+, and Cd 2+ ) on the photodegradation of several dyes: sulfo-rhodamine B (SRB), alizarin red (AR), and malachite green (MG) has been investigated in aqueous TiO 2 dispersions under visible irradiation (λ > 420 nm). Trace quantities of transition metal ions such as Cu 2+ and Fe 3+ having suitable redox potentials alter the electron-transfer pathway involving the dye, O 2 and TiO 2 particles, and markedly depress the photodegradation of all three dyes under visible irradiation. Other metal ions, such as Zn 2+, Cd 2+, and Al 3+, have only a slight influence on the photoreaction by altering the adsorption of dyes. Photogeneration of H 2 O 2 and reactive radicals, and the changes in fluorescence emission of SRB in TiO 2 aqueous dispersions were examined to elucidate the role of the metal ions. Addition of Cu 2+ or Fe 3+ decreases the reduction of O 2 by the conduction electrons, subsequently blocks the formation of reactive oxygen species (O -•, • OH), and depresses the degradation of dyes under visible irradiation. We deduce that the reduction of O 2 is essential for the photodegradation of dyes under visible irradiation.
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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) | 0.001 | 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".