Oxidation of H<sub>2</sub>, CH<sub>4</sub>, and CO Molecules at the Interface between Nickel and Yttria-Stabilized Zirconia: A Theoretical Study Based on DFT
Bibliographic record
Abstract
Activation of fuel molecules (H 2, CH 4, CO) at the anode triple phase boundary (TPB) of a solid oxide fuel cell, modeled by a Ni (nickel)/YSZ (yttria-stabilized zirconia)/fuel interface is investigated using density functional theory. We demonstrate that, by employing ab initio calculations, it is possible to elucidate the mechanisms of electronic charge transfer and current generation as a result of electrochemical oxidation of fuel in the anode TPB. Moreover, we show that an oxygen-enriched YSZ surface (YSZ+O) of the Ni/YSZ cermet is significantly less active toward oxidation of fuel molecules than an oxygen-enriched YSZ surface in the absence of Ni, which is explained by partial saturation of the valence of an extra oxygen atom of the Ni/YSZ cermet. On the other hand, the chemical activity of the Ni part of the cermet is close to that of the infinite Ni surface, even in the proximity to the YSZ. The YSZ+O surface of the cermet is found generally inert, as adsorption of H 2 and CH 4 is associated with high kinetic barriers, whereas CO adsorption is a more favorable, although endothermic reaction. The oxidation of H 2 and CO on Ni after oxygen spillover from the oxide is exothermic, and CH 4 oxidation is mildly endothermic. It is also shown that transfer of hydrogen atoms from Ni to YSZ (hydrogen spillover reactions) with subsequent water formation is another possible scenario of hydrogen oxidation on the YSZ+O surface.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".