<i>In Situ</i>Raman Studies of Carbon Removal from High Temperature Ni–YSZ Cermet Anodes by Gas Phase Reforming Agents
Bibliographic record
Abstract
In situ vibrational Raman scattering has been employed to examine rates of carbon formation and removal from Ni/YSZ cermet anodes in functioning, electrolyte-supported solid oxide fuel cells (SOFCs). Specifically, Raman scattering characterized the ability of different gas phase species commonly used as reforming agents to remove carbon that had accumulated on Ni/YSZ cermet anodes at 730 °C. Anodes held at open circuit voltage (OCV) were exposed first to a dry methane feed and then to an inert carrier gas containing either H 2 O (g), CO 2, or O 2 . Carbon deposits began to form within 5 s of methane exposure. Vibrational Raman spectra showed that the carbon deposits consisted of highly ordered graphite as evidenced by a single pronounced feature in the spectra at 1556 cm –1 . Changing the incident gas phase environment over the anode to Ar containing either H 2 O (2%), CO 2 (6%), or O 2 (6%) led to quantitative removal of the carbon and partial or complete oxidation of the Ni as evidenced by the growth of a NiO vibrational band (at 1080 cm –1 ) in the Raman spectra. Carbon removal rates from the Ni/YSZ anode were fastest with vapor phase H 2 O, then O 2, and finally slowest with CO 2 . The extent of Ni oxidation was much more pronounced with O 2 than with either H 2 O or CO 2 . These chemical processes observed directly in the Raman spectra were reflected in the device’s open circuit voltage (OCV). Correlating findings from these two methods— in situ Raman spectroscopy and voltage measurements—provided a direct connection between the chemical composition of SOFC anodes and the electrochemical condition of the device. These results inspire confidence that any of the reforming agents used—H 2 O, O 2, and CO 2 —will remove carbon from Ni anodes quantitatively on a time scale of ∼10 to ∼125 s. However, H 2 O and CO 2 appear less likely to damage the cell following carbon removal, as H 2 O and CO 2 do not quantitatively oxidize the Ni in the cermet anode. In contrast, exposure to O 2 leads to much more extensive Ni oxidation and an OCV that approaches 0.0 V, implying that the Ni/NiO equilibrium sustained by H 2 O and CO 2 is driven completely to NiO by O 2 .
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".