All-Edge MoS₂ by Ultramicrotomy for Hydrogen Evolution

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Molybdenum disulfide (MoS₂) is a key catalyst for the hydrogen evolution reaction (HER).
• Edge sites are more catalytically active than basal planes, but precise control over MoS₂ structure is limited.
• Existing methods produce mixed basal plane and edge sites, hindering controlled active site exposure.

Purpose of the Study:

• To develop a precise method for fabricating MoS₂ structures with exclusively edge terminations.
• To investigate the influence of edge morphology, alignment, and accessibility on HER performance.
• To understand the relationship between structure, electron transport, and catalytic activity.

Main Methods:

• Fabrication of MoS₂ structures using an ultramicrotomy slicing technique.
• Creation of all-edge MoS₂ terminations with tunable spacing and electrode distance.
• Electrochemical benchmarking of HER performance on glassy carbon electrodes.
• Decoration with gold (Au) nanoparticles to assess performance enhancement.

Main Results:

• Precision-sliced all-edge MoS₂ structures showed tunable morphology and alignment.
• Thinner, disordered, and open-edge structures outperformed thicker, compact, and aligned ones.
• Catalytic performance is influenced by edge accessibility, geometric openness, and basal plane electron transfer resistance.
• Pristine vMoS₂-⊥ had an overpotential of ~300 mV at 10 mA cm^-2; Au decoration reduced it to 180 mV.

Conclusions:

• The study provides a platform for rational edge engineering in 2D electrocatalysts.
• Findings offer mechanistic insights into HER activity in MoS₂.
• The slicing technique shows potential for scalable production of tailored MoS₂ catalysts.