Spectral Dependencies of the Quantum Yield of Photochemical Processes on the Surface of Nano/Micro-Particulates of Wide-Band-Gap Metal Oxides. IV. Theoretical Modeling of the Activity and Selectivity of Semiconductor Photocatalysts with Inclusion of a Subsurface Electric Field in the Space Charge Region
Bibliographic record
Abstract
In an earlier study (Emeline, A. V.; Ryabchuk, V. K.; Serpone, N. J. Phys. Chem. B 1999, 103, 1316) we reported the solution to the continuity equation in which we neglected electric field effects and obtained expressions for the concentrations of the charge carriers at the surface ( n s ), for the quantum yield (Φ) of a photochemical surface redox reaction, together with an expression for the selectivity of the photocatalyst. Various considerations led us to infer and predict wavelength-dependent phenomena (quantum yields and selectivity), which were later confirmed by experimental results (Emeline, A. V.; Serpone, N. J. Phys. Chem. B 2002, 106, 12221). In this article we revisit the continuity equation but include a subsurface electric field ( E ) in the space charge region of the semiconductor (or dielectric) photocatalyst to assess the effect that the electric field has on the activity and selectivity of the photocatalyst. The solution to the continuity equation yields very complex expressions for n s and for Φ. Nonetheless, several cases are considered which simplify the expressions. Taking E = 0, the expression for the quantum yield transforms into the identical equation obtained earlier. Some of the predictions from the expressions obtained herein also find experimental verification from considerations, for example, of the quantum yields of photoadsorption of dioxygen and dihydrogen on TiO 2 particles. The agreement between the predicted spectral behavior of the ratio γ = [e s ]/[h s ] against wavelength with the spectral dependence of Φ O 2 /Φ H 2 is remarkable. Another no less significant conclusion from the theoretical modeling results is that a mismatch between the experimental spectral dependence of the quantum yield and the corresponding absorption band may be an indicator of the existence of a space charge region in the solid photocatalyst.
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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 | 0.001 |
| 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 | 0.001 |
| 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".