Surface Analogues of Molecular Frustrated Lewis Pairs in Heterogeneous CO<sub>2</sub> Hydrogenation Catalysis
Bibliographic record
Abstract
The discovery of homogeneous, solution-based molecular frustrated Lewis pairs, denoted FLPs, comprising main-group elements that can activate H 2 heralded a paradigm shift in chemistry and catalysis. In FLPs, unquenched Lewis base and Lewis acid sites (B···A) are able to polarize and dissociate H 2 heterolytically to form adjacent proton and hydride sites (BH – ···AH + ), which can enable reactions such as CO 2 reduction. In this paper, we draw attention to a relationship between these well-known molecular FLPs and the surface active sites comprised of proximal Lewis base and Lewis acid pairs, which have been reported multiple times in the literature to be responsible for driving various heterogeneous catalytic reactions. From our recent studies that described one such surface site in a nanostructured defect laden indium oxide, capable of activating H 2 and enabling the hydrogenation of CO 2, it was conjectured that these sites are surface FLPs. Significantly, the conversion rate for this hydrogenation reaction is observed to be more rapid in the light than in the dark. Kinetic measurements and density functional theory simulations are consistent with a reaction that proceeds via a surface FLP. It is found that the higher Lewis acidity and Lewis basicity in the excited state, which originates from trapping of the photogenerated hole and electron at the FLP acid and base sites, respectively, is responsible for the higher reactivity in the light in comparison to the dark. With the emerging experimental and theoretical understanding of the chemical and physical principles that underpin the reactivity of FLPs in both homogeneous and heterogeneous systems, it is now possible to rationally conceive and synthetically target heterogeneous FLP materials that bear a compositional and structural connection to homogeneous FLP molecules, and vice versa. This synergistic relationship between FLP molecules and materials could prove beneficial in future efforts aimed at expanding the accrued scientific knowledge on photochemical versus thermochemical activation of CO 2 and thereupon to exploit the perceived technological attributes of both systems in the catalytic conversion of carbon dioxide to value-added chemicals and fuels.
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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 | 0.001 | 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".