Adsorption and Decomposition of a Lignin β-O-4 Linkage Model, 2-Phenoxyethanol, on Pt(111): Combination of Experiments and First-Principles Calculations
Bibliographic record
Abstract
To sustain the current attempts in valorizing lignin-based derivatives, this study focuses on the decomposition upon a temperature ramp of 2-phenoxyethanol, a model for the β-O-4 linkage in lignin, on a Pt(111) surface. Under ultrahigh-vacuum conditions, benzene, hydrogen, and carbon monoxide are the main desorbing products. Although benzene is the only aromatic desorbed product at low initial molecular coverages, very small amounts of phenol can be detected at higher initial coverage. Combining X-ray photoelectron spectroscopy and temperature-programmed desorption experiments together with density functional theory calculations, a reaction mechanism is suggested, starting with the OH bond scission. Phenoxy, PhO, is proposed as a key surface intermediate that preferentially deoxygenates rather than desorbs as phenol, similarly to the case of anisole. This behavior, typical of ultrahigh-vacuum conditions, is attributed to the reducing properties of carbonaceous surface species that efficiently deoxygenate phenoxy and afford the formation of the very stable carbon monoxide.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".