Tuning the Basal Plane Functionalization of Two-Dimensional Metal Carbides (MXenes) To Control Hydrogen Evolution Activity
Bibliographic record
Abstract
Hydrogen evolution reaction (HER) via electrocatalysis is one method of enabling sustainable production of molecular hydrogen as a clean and promising energy carrier. Previous theoretical and experimental results have shown that some two-dimensional (2D) transition metal carbides (MXenes) can be effective electrocatalysts for the HER, based on the assumption that they are functionalized entirely with oxygen or hydroxyl groups on the basal plane. However, it is known that MXenes can contain other basal plane functionalities, e.g., fluorine, due to the synthesis process, yet the influence of fluorine termination on their HER activity remains unexplored. In this paper, we investigate the role and effect of basal plane functionalization (T x ) on the HER activity of 5 different MXenes using a combination of experimental and theoretical approaches. We first studied Ti 3 C 2 T x produced by different fluorine-containing etchants and found that those with higher fluorine coverage on the basal plane exhibited lower HER activity. We then controllably prepared Mo 2 CT x with very low basal plane fluorine coverage, achieving a geometric current density of −10 mA cm –2 at 189 mV overpotential in acid. More importantly, our results indicate that the oxygen groups on the basal planes of Mo 2 CT x are catalytically active toward the HER, unlike in the case of widely studied 2H-phase transition metal dichalcogenides such as MoS 2, in which only the edge sites are active. These results pave the way for the rational design of 2D materials for either the HER, when minimal overpotential is desired, or for energy storage, when maximum voltage window is needed.
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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.
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".