Electronic structure study of H3BXH3 (X-B, N and P) as hydrogen storage materials using calculated NMR and XPS spectra
Bibliographic record
Abstract
Boron-based materials have been used for hydrogen storage applications owing to their high volumetric and gravimetric hydrogen density. The present study quantum mechanically investigates the electronic structures of three compounds: diborane (DB, B2H6), ammonia borane (AB, H3BNH3) and phosphine borane (PB, H3BPH3). The exploration is facilitated using calculated nuclear magnetic resonance (NMR) chemical shifts, together with outer valence ionisation potentials (IP) and core electron binding energy (CEBE). The findings show a distinct electronic structure for diborane, differing notably from AB and PB, which exhibit certain similarities. Noteworthy dissimilarities are observed in the chemical environments of the bridge hydrogens and terminal hydrogens in diborane, resulting in a substantial chemical shift difference of up to 5.31 ppm. Conversely, in AB and PB, two distinct sets of hydrogens emerge: protic hydrogens (Hp–N and Hp–P) and hydridic hydrogens (Hh–B). This leads to chemical shifts as small as 0.42 ppm in AB and as significant as 3.0 ppm in PB. The absolute isotropic NMR shielding constant (sB) of 11B in DB is 85.40 ppm, in contrast to 126.21 ppm in AB and 151.46 ppm in PB. This discrepancy indicates that boron in PB has the most robust chemical environment among the boranes. This assertion finds support in the calculated CEBE for B 1s of 196.53, 194.01 and 193.93 eV for DB, AB and PB respectively. It is clear that boron in PB is the most reactive atom. Ultimately, understanding the chemical environment of the boranes is pivotal in the context of dehydrogenation processes for boron-based hydrogen storage materials.
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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) | 0.002 | 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".