Pit Formation Mechanism of Monolayer MoS<sub>2</sub> By Thermal Oxidation
Bibliographic record
Abstract
Generating pits and thereby active edge sites of molybdenum disulfide (MoS2) monolayers is desirable for many electrochemical catalytic reactions including hydrogen evolution reaction (HER). Thermal oxidation is one of the potentially scalable and facile methods to effectively create the pits on MoS2 monolayers. Therefore understanding the thermal oxidation mechanism is very important to precisely control the generation of active edge sites of MoS2-based electrocatalysts. To date, pits are assumed to be favorably formed on MoS2 at undercoordinated sites such as sulfur (S) vacancies at high temperatures. However, the thermal oxidation studies have not considered the existence of adventitious carbon (C) that exists almost everywhere and interact with oxygen at elevated temperatures. Herein, we investigated the influence of adventitious C on the thermal oxidation of MoS2 monolayers. We employed in situ environmental transmission electron microscopy (ETEM) to demonstrate the pit formation mechanism with the presence of adventitious C at the oxidation temperature of 300 °C. The in situ ETEM results show that the adventitious C is agglomerated at high temperatures. Then, the interfaces between monolayer MoS2 and C nanoparticle provide preferred sites for thermal oxidation of MoS2 and thus pit formation while the individual S vacancies exist intact. Density functional theory (DFT) calculations show the interfaces between MoS2 and C nanoparticle make the sequential adsorption of oxygen atoms thermodynamically favorable, unlike only S vacancy sites. We also tested the electrochemical performance of MoS2 with pits for HER and it reduced the overpotential by ~ 130 mV. These results demonstrate the combination between ETEM experiment and DFT calculation can be effectively used to study the chemical reaction mechanism between 2-dimensional materials such as MoS2 and gaseous species. Furthermore, we provide the potential to control the active edge site of MoS2-based electrocatalyst by understanding the fundamental pit formation mechanism by thermal oxidation.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".