Supported metal sulphide nanoclusters studied by HAADF-STEM

Area of Science:

• Materials Science
• Nanotechnology
• Surface Chemistry

Background:

• Molybdenum disulfide (MoS2) and tungsten disulfide (WS2) are layered transition metal dichalcogenides with significant catalytic and electronic properties.
• Understanding the morphology of nanoclusters is crucial for optimizing their performance in various applications.
• High-surface area graphitic carbon supports are commonly used to disperse and stabilize these nanoclusters.

Purpose of the Study:

• To investigate the morphology of MoS2 and WS2 nanoclusters supported on graphitic carbon.
• To determine the influence of nickel on the nanocluster morphology.
• To characterize the formation of Ni-Mo-S and Ni-W-S structures.

Main Methods:

• High-angular annular dark-field scanning transmission electron microscopy (HAADF-STEM) was employed for high-resolution imaging.
• Characterization of nanocluster shapes and sizes.
• Analysis of elemental composition to identify Ni-Mo-S and Ni-W-S phases.

Main Results:

• MoS2 and WS2 nanoclusters predominantly adopt a single-layer, truncated triangular morphology.
• This contrasts with the hexagonal morphology of larger MoS2 and WS2 crystals.
• The presence of nickel leads to further truncation, forming Ni-Mo-S (Ni-W-S) structures with dodecahedral-like shapes.

Conclusions:

• The morphology of MoS2 and WS2 nanoclusters is sensitive to support interactions and composition.
• Nickel incorporation significantly alters nanocluster morphology, favoring more complex, truncated shapes.
• These findings provide insights into the structure-property relationships of transition metal dichalcogenide nanoclusters for catalysis and materials science.