Metastable Au<sub><i>x</i></sub>Rh<sub>100–<i>x</i></sub> Thin Films Prepared by Pulsed Laser Deposition for the Electrooxidation of Methanol
Bibliographic record
Abstract
Metastable Au x Rh 100– x thin films were prepared by crossed beam pulsed laser deposition on two different substrates. High kinetic-energy deposition conditions were used (0.1 Torr He, 5.5 cm target-to-substrate distance). The films were characterized by X-ray diffraction and X-ray photoelectron spectroscopy, and their electrocatalytic activities for the electrooxidation of methanol were assessed by linear sweep voltammetry in 1 M NaOH. All films are made of a single fcc phase compound. For 40 < x < 85 at %, the lattice parameter deviates slightly from that expected from Vegard’s law. The XRD patterns of Au x Rh 100– x /C and Au x Rh 100– x /Si did not evolve over a period of 1 year, indicating that the solid solution is kinetically stable. However, as expected from the Au–Rh binary phase diagram, heat treatment of Au 50 Rh 50 /C at 500 °C in Ar during 24 h leads to decomposition of the metastable fcc phase and the formation of Rh and Au. X-ray photoelectron spectroscopy revealed that the Au surface composition closely follows the Au bulk content. The binding energy difference between the Rh 3d 5/2 and Au 4f 7/2 core level peaks shifts from 223.3 to 222.4 eV as x is increased from 5 to 95, indicating that a surface alloy is formed between Au and Rh. In the presence of methanol, Au x Rh 100– x /C with x = 25, 50, and 75 shows a methanol oxidation peak (a 2 ) in a potential region (ca. −0.12 V vs Hg/HgO), where pure Au and Rh do not exhibit any electrocatalytic activity for methanol oxidation. The current of peak a 2 increases with the methanol concentration. The formation of a surface alloy significantly improves the electrocatalytic activity for methanol oxidation by providing OH – species at lower potential (by 400 mV) compared with pure Au.
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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".