Visualizing 4D Pore-Scale Gas Transport in Operating PEM Electrolyzers Using X-Ray Computed Tomography
Bibliographic record
Abstract
Mass transport losses in polymer electrolyte membrane (PEM) electrolyzers are predominantly caused by the accumulation of oxygen gas within the pores of the porous transport layer (PTL), hindering reactant water delivery to reaction sites (1). To enhance mass transport and optimize electrolyzer performance, a comprehensive understanding of the mechanisms driving oxygen gas transport in the PTL is required. Numerous studies have utilized various imaging techniques - including optical, neutron, and X-ray radiography to elucidate the evolution and transport of oxygen gas in the multiphase flow regime during PEM electrolyzer operation (2). However, these techniques only capture two-dimensional (2D) images, resolving average gas distributions rather than a holistic pore-scale quantification. Few studies have used three-dimensional (3D) imaging to resolve the dynamic microscale distributions of oxygen gas in the PTL. Understanding the impact of key parameters affecting 3D oxygen gas transport, such as PTL morphology, will allow for tailored pore-scale material optimization for enhanced gas transport and improved performance of PEM electrolyzers. This study presents a non-destructive operando imaging approach using X-ray computed tomography (CT), enabling the visualization of transient 3D oxygen gas evolution and transport in the PTL of a PEM electrolyzer. Using state-of-the-art synchrotron X-rays, high temporal and spatial resolutions were achieved to capture the pore-scale formation and growth of oxygen gas pathways within the PTL at various operating conditions. Electrochemical performance of an in-house designed electrolyzer cell was also characterized while acquiring tomographic images to investigate the impact of observed transport mechanisms on performance. The methodology presented in this work showcases the capability of using X-ray CT to visualize the complex interfacial multiphase flow in PTLs. Findings from this study will provide valuable insight towards pore-scale material optimization of clean energy porous materials aimed at curtailing the costs of green hydrogen production. References 1. M. Suermann, T. J. Schmidt, and F.N. Büchi, ECS Trans., 69(17), 1141-1148 (2015). 2. M. Maier, K. Smith, J. Dodwell, G. Hinds, P. R. Shearing, and D. J. L. Brett, Int. J. Hydrog. Energy., 47(1), 30-56 (2022).
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".