Unveiling hydrogen evolution dependence on KOH concentration for polycrystalline and nanostructured nickel-based catalysts
Bibliographic record
Abstract
Abstract Nickel-based hydrogen evolution reaction (HER) electrodes have been widely used in alkaline and anion exchange membrane water electrolysis. Therefore, understanding the activity dependence on the KOH concentration (pH) of alkaline electrolytes is essential for designing durable and active HER catalysts. In this work, the HER activity and kinetics of polycrystalline and nanostructured nickel-based catalysts are evaluated in various pH and KOH concentrations. The results for nanostructured NiMo catalyst indicate that both electrochemical active surface area and reaction order have a promoting region under various pH’s and KOH concentrations (0.01–1.0 M, pH 12–14) accompanied by better HER activity (a lower overpotential for achieving − 10 mA cm −2 ) and Tafel slope decreases from around 180 mV dec −1 to 60 mV dec −1 in the same pH and KOH concentration range. The change in the Tafel slope indicates that the HER rate-determining step for HER at NiMo/C changes with pH and KOH concentration. The polycrystalline Ni displays different behaviours where a promoting (0.01–0.10 M, pH 12–13), stabilizing (0.1–1.0 M, pH 13–14), and an inhibiting region (2 M, pH > 14) are present. However, Tafel slopes of around 120 mV/dec are obtained for polycrystalline Ni at all KOH concentrations. The HER characteristics are inhibited at 2.0 M KOH for both catalysts due to slower OH* transport kinetics. The results confirmed the importance of tuning catalyst-pH/KOH concentration for better HER activity and kinetics. Graphical abstract
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".