Assessing Proton and Hydrogen Permeabilities for Nanoscopic Oxide Coatings Using a Rotating Disk Electrode
Bibliographic record
Abstract
The transport of protons and molecular hydrogen (H2) are of relevance to a wide range of electrochemical applications ranging from fuel cells and electrolyzers to sensors and photoelectrochemical cells. One way to modulate the flux of these species to improve device performance such as selectivity and efficiency is to encapsulate electrodes with semi-permeable oxide coatings. [1-3] Thus, knowing the permeabilities of these species within thin oxide layers is of great importance for guiding the design of electrodes and devices. Towards this end, we have employed a modified rotating disk electrode (RDE) set-up to quantify proton and hydrogen permeabilities through sub- 20 nm thick silicon oxide coatings and understand how these transport properties change as a function of the structural and compositional characteristics of the coatings. Oxide coatings were fabricated by both atomic layer deposition (ALD) and photochemical deposition, and their physical and chemical properties characterized by X-Ray Photoelectron spectroscopy and ellipsometry. Based on measurements of the mass transfer limited current density for the hydrogen evolution and hydrogen oxidation reactions, permeabilities were computed. Species permeabilities are furthermore correlated with membrane density and composition, revealing structure-property-performance relationships that can be used to guide the selection of oxide thickness and processing conditions that will optimize performance for an application of interest. References: [1] Labrador, N. Y., et al. Hydrogen evolution at the buried interface between Pt thin films and silicon oxide nanomembranes. ACS Catalysis 8, 1767-1778 (2018). [2] Beatty, M. E., Gillette, E. I., Haley, A. T. & Esposito, D. V. Controlling the Relative Fluxes of Protons and Oxygen to Electrocatalytic Buried Interfaces with Tunable Silicon Oxide Overlayers. ACS Applied Energy Materials 3, 12338-12350 (2020). [3] Bhardwaj, A. A., et al. Ultrathin silicon oxide overlayers enable selective oxygen evolution from acidic and unbuffered pH-neutral seawater. ACS Catalysis 11, 1316-1330 (2021).
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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 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".