Abstract
Chemical vapor deposition (CVD)-grown 2D transition metal dichalcogenides can adopt faceted edges. To investigate how sharp these sites can be, we utilize aberration-corrected annular dark-field scanning transmission electron microscopy (ADF-STEM) to resolve the atomic structure of two-dimensional (2D) WS2 domains that show jagged edges. Nanoscale triangular edge structures with S zigzag terminations are observed. Both the peak and valley regions exhibit near-atomic sharpness. The peaks are as sharp as two atoms in width. Highly ordered valley sites display a minimum width of three atoms, and prospective single-atom valleys appear as two-atom-wide sites in the ADF-STEM contrast. Regarding the kinetics, density-functional theory (DFT) calculations indicate that the 2-W-atom peak would not evolve into a single-W-atom peak even though the latter configuration is also stable with a high enough binding energy under the growth conditions. These results help deepen our understanding of the possible structuring at the nanoscale and the atomic-scale limits of peaks and valleys formed via intersection of two zigzag edges. The enriched edge sites lead to higher catalytic activities for the hydrogen evolution reaction (HER).
Original language | English |
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Article number | 100183 |
Journal | Materials Today Nano |
Volume | 18 |
DOIs | |
State | Published - Jun 2022 |
Externally published | Yes |
Funding
The authors thank Diamond Light Source for the use of the electron Physical Science Imaging Center and Si Zhou for help in acquiring some of the preliminary data. W.X. acknowledges the support from China Postdoctoral Science Foundation ( 2021M692172 ). G.S.J. appreciates the support from the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory (Eugene P. Wigner Fellowship). This work utilized the resources of the Compute and Data Environment for Science at the Oak Ridge National Laboratory, which is provided by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725.
Keywords
- Growth kinetics
- Hydrogen evolution reaction
- Scanning transmission electron microscopy
- Tungsten disulfide
- Two-dimensional materials