Kinetics and Mechanism of Turanite Reduction by Hydrogen
Bibliographic record
Abstract
Turanite, Cu₅(VO₄)₂(OH)₄, is a naturally occurring mineral whose physical and chemical properties are of interest for magnetic data storage, battery applications, and catalysis. In this study, the reduction of nanostructured Cu₅(VO₄)₂(OH)₄ by H₂ is investigated using a combination of scanning transmission electron microscopy–electron energy-loss spectroscopy, X-ray photoelectron spectroscopy, in situ diffuse reflectance infrared Fourier transform spectroscopy, in situ X-ray absorption spectroscopy, first-principles calculations, and kinetic analysis based on thermogravimetry. A two-step mechanism is proposed, in which Cu₅(VO₄)₂(OH)₄ is first reduced, following exponential growth kinetics, to form a stable intermediate consisting of a mix of Cu₃VO₄, Cu₂O, and CuV₂O₅. The intermediate phase is then subsequently reduced in a 3-D diffusion-limited process to form two segregated phases consisting of Cu metal and V₂O₃ particles. The apparent energy barriers for these two steps, obtained from the kinetic analysis, were found to be 52.5 and 71.2 kJ mol–¹ for Stages 1 and 2 of the reduction, respectively. These results highlight the importance of developing a rigorous understanding of the reduction processes involved in metal oxide catalyst preparation.
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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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".