Mesoporous Nickel−Yttria−Zirconia Fuel Cell Materials
Bibliographic record
Abstract
A novel synthesis method for mesoporous nickel−yttria−zirconia (meso-Ni−YZ) has been developed using a surfactant-templated co-assembly strategy, involving yttrium(III)−zirconium(IV) glycometalate and nickel(II) precursors. Nickel loading has been investigated over the range 0−45 Ni at. % and found to control the average pore size of the oxidized meso-NiO 1+ x −YZ and reduced meso-Ni−YZ products. Under the synthesis conditions utilized, the cationic surfactant glycometalate co-assembly is proposed to involve nickel in the form of Ni 4 (OH) 4 4+, which subsequently transforms to a co-assembly containing nanoscale Ni(OH) 2 . Upon thermal posttreatment in air, the nickel hydroxide species is converted to the nanocrystalline p-type nickel oxide, NiO 1+ x, located in the pores of meso-NiO 1+ x −YZ. The channel walls of meso-NiO 1+ x −YZ are composed of nanocrystalline yttria−zirconia, and the gas adsorption isotherm appears as type I. Thermal reduction of the NiO 1+ x component of the mesostructure in hydrogen creates nickel nanocrystals. A concomitant dramatic increase in average pore diameter is observed with concurrent evolution of an adsorption isotherm of type IV. This behavior is attributed to a structural transformation of meso-NiO 1+ x −YZ to meso-Ni−YZ involving a reduction in NiO 1+ x nanocrystal size on conversion to Ni with accompanying migration and aggregation of Ni nanocrystals. The outcome of these combined effects widens the pores within meso-Ni−YZ relative to meso-NiO 1+ x −YZ. Preliminary ac impedance spectroscopy of meso-Ni−YZ at a loading of less than 40 at. % Ni depicts an electrical response dominated by oxygen ion conductive nanocrystalline YZ channel walls of the meso-Ni−YZ mesostructure. By contrast, higher nickel loaded meso-Ni−YZ samples give a metallic response most likely due to a better connectivity of Ni nanocrystals within the mesostructure.
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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 | 0.001 |
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".