Sulfuric Acid Electrolyte Impacts Palladium Chemistry at Reductive Potentials
Bibliographic record
Abstract
We report herein that sulfuric acid electrolyte affects the kinetics of hydrogen sorption and desorption, the amount of absorbed hydrogen, and the electrocatalytic activity of palladium using X-ray photoelectron spectroscopy (XPS) and in situ temperature-programmed desorption (TPD). This study utilized a custom TPD instrument tailored to the in situ characterization of palladium films electrochemically saturated with absorbed hydrogen (PdH x for x > 0.6), and we present the first experimental data for the formation of sulfates on palladium hydride at E < 0 V (vs RHE). The surface adsorption of sulfates leads to a retardation of hydrogen sorption and desorption kinetics by increasing the desorption energy of absorbed hydrogen by 92 kJ mol –1 relative to a clean palladium surface. Although previous studies have reported that the SO 4 2– anions of H 2 SO 4 only adsorb on palladium under oxidative potentials E > 0.5 V (vs RHE), the differing chemistry of hydrogen-free and hydrided palladium was not considered. The sulfate adsorbates affect the reaction chemistry through both a competitive binding of surface sites and by altering the electronic structure of surface atoms. The influence of the electrolyte is evidenced by a sluggish kinetics of H absorption and desorption in H 2 SO 4 electrolyte relative to HCl, concomitant with a lower hydrogen uptake in H 2 SO 4 ( x = 0.64 ± 0.01) versus HCl ( x = 0.697 ± 0.007). The findings of this study emphasize the critical and often overlooked role of the electrolyte utilized in electrochemical studies of the palladium–hydrogen system.
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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 | 0.000 | 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.
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