Catalytic Activity of BaTiO<sub>3</sub> Nanoparticles for Wastewater Treatment: Piezo- or Sono-Driven?
Bibliographic record
Abstract
Piezocatalytic reactions are generally excited by ultrasonication and, as such, should occur simultaneously with other catalytic reactions caused by different mechanisms such as sonocatalysis or tribocatalysis. One of the main challenges is how to discriminate between these effects in a catalysis experiment and quantify each contribution. In order to distinguish these effects, we use nano- and micro-particles of piezoelectric barium titanate (BaTiO 3 ) and then compare their catalytic properties below and close to the piezoelectric to non-piezoelectric phase transition temperature at which the crystalline structure changes from the low-temperature tetragonal, piezoelectric phase to the higher-temperature cubic, non-piezoelectric phase. All other parameters, such as particle size, surface termination, etc., remain unaltered. The phase transition in bulk occurs at about 120 °C, but the transition temperature decreases as a function of particle size and reaches room temperature for particle sizes of about 20 nm. Transmission electron microscopy and X-ray diffraction were used to characterize the morphology and crystalline phase of the nanoparticles, respectively. Since the piezoelectric properties and the lattice dynamics are closely related, temperature-dependent Raman spectroscopy provides an even better insight into the nano- and micro-structural properties, allowing the ferroelectric phase transition temperature to be estimated. The catalytic activities of the BaTiO 3 nanoparticles were determined by monitoring the optical absorption of a solution containing the model pollutant methyl orange, after ultrasonication of the solution to which were added the dispersed piezoelectric BaTiO 3 particles as catalysts. An exponential-like correlation has been found between the catalytic reaction rates and the tetragonal distortion of the crystal structure of the BaTiO 3 particles. Our study has also established that while 10% of the catalytic reaction of BaTiO 3 is related to either sonocatalysis or tribocatalysis, the remaining 90% of the overall catalytic activity is ascribed to the piezocatalytic contribution.
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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".