Single cobalt atoms with unconventional dynamic coordination mechanism for selective ammonia sensor
Why this work is in the frame
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Bibliographic record
Abstract
ABSTRACT Developing gas sensors that can simultaneously achieve high sensitivity and selectivity for the detection of a single-type gas remains a significant challenge. Herein we demonstrate cobalt (Co) single atoms with an unconventional dynamically changing coordination structure that could be used as NH3-sensing material with superior sensitivity and selectivity. According to the steric effect of 2-methylimidazole (2MI) molecules and carbonyl groups on graphene, the Co single atom is evolved into a bidentate coordinated structure (Co-2MI-G). In-situ characterization and theoretical simulation reveal that the sensing mechanism of Co-2MI-G is the specific chemical adsorption between unsaturated coordinated Co single atoms and NH3 molecules, causing a reversible switching of coordination number from 2 to 4, a valence state transfer from Co2+ to Co3+ of Co single atoms, and a band-gap width from 0.14 eV to 0.50 eV. Consequently, the Co-2MI-G-based gas sensor presents a sensing response of 67.598% for 1 ppm NH3 and a limit of detection of 2.67 ppb, at least 1.8 times higher than that of state-of-the-art NH3 sensors, together with robust stability and reproducibility. This work provides an innovative perspective on utilizing single atoms for ultra-selective gas sensing by coordination regulation.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.000 | 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 it