In Situ X-ray Spectroscopy Unveils Charge-Driven CO Oxidation over Cu-TiO <sub>2</sub> Mesospheres
Bibliographic record
Abstract
Carbon monoxide (CO), a hazardous byproduct of incomplete hydrocarbon combustion, poses significant environmental and health concerns. Efficient and low-temperature catalytic oxidation of CO to CO 2 remains a key challenge. In this study, Cu-doped TiO 2 nanostructures with varying Cu contents (0–20 wt %) were synthesized via a one-step aerosol-assisted self-assembly (AASA) method. X-ray diffraction confirmed the anatase TiO 2 phase, and Brunauer–Emmett–Teller (BET) analysis revealed an increased pore size at higher Cu loadings. The 20 wt % Cu-TiO 2 (20CTO) sample exhibited superior CO oxidation performance, initiating conversion at ∼90 °C. Synchrotron X-ray fluorescence mapping showed more uniform Cu dispersion in 20CTO than in 10CTO. Site-dependent charge dynamics of Cu observed at lower dopings (5CTO, 10CTO) diminished in 20CTO. X-ray absorption near edge structure (XANES) revealed a higher Cu oxidation state (>2+) and a reduced unoccupied density of Ti states in 20CTO, indicating charge transfer from Cu to Ti. Extended X-ray absorption fine structure (EXAFS) analyses showed altered Cu–O and Ti–O coordination at higher Cu loading. In site XANES revealed that Cu’s unoccupied states decreased with increasing temperature, while Ti exhibited increased octahedral symmetry and unoccupied states. Spectromicroscopic analysis confirmed spatially heterogeneous distributions of Ti 4+ and Cu 2+ states in 20CTO. These findings underscore the role of Cu doping in modulating the local electronic structure and promoting low-temperature CO oxidation.
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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".