(Invited) Nanogap Voltammetry of Clean Surface of Electron-Beam-Deposited Carbon
Bibliographic record
Abstract
Clean surfaces of conducting carbon materials are highly demanded for fundamental and applied electrochemistry to mechanistically understand and practically utilize their intrinsic reactivity. In this presentation, we will discuss about the nanoelectrochemical characterization of clean carbon surfaces to gain novel insights into heterogeneous electron-transfer (ET) mechanism with broad implications beyond carbon electrochemistry. Electron-beam deposited carbon (eC) is formed in high vacuum (<6 µtorr) and protected from adventitious contamination by a washable KCl layer deposited without breaking vacuum. Fast ET kinetics of exceedingly flat, clean eC surfaces is reliably measured in ultrapure water using nanogap voltammetry based on scanning electrochemical microscopy and compared quantitatively with Marcus and Frumkin theories. An outer-sphere ET mechanism, which is typically only presumed, is evidenced experimentally for (ferrocenylmethyl)trimethylammonium and tris(1,10-phenanthroline)cobalt(II) (Co(phen)3 2+) by excluding an inner-sphere mechanism. Indeed, the oxidation of Co(phen)3 2+ agrees unprecedentedly well with Marcus theory of adiabatic outer-sphere kinetics in comparison to any redox couple on carbon or metal electrodes reported previously. The coupled reduction of Co(phen)3 3+ deviates from Marcus theory to reveal a unique double-layer effect caused by the adsorption of a redox molecule itself, i.e. Co(phen)3 2+, which contrasts to the Frumkin effect based on the adsorption of inert electrolytes. Remarkably, the Ru(NH3)6 3+/2+ couple exceeds adiabatic limits not only at eC, but also at other carbons and metals, which we attribute to faster inner-sphere ET of adsorbed forms of this couple. In contrast, an inner-sphere pathway is not mediated by the adsorbed Fe(CN)6 3–/4– couple, which dramatically self-decelerates the outer-sphere pathway through a double-layer effect.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 0.001 |
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".