Enhancing hydrogen evolution reaction activity through defects and strain engineering in monolayer MoS₂.

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Molybdenum disulfide (MoS₂) is a promising electrocatalyst for the hydrogen evolution reaction (HER).
• Poor in-plane conductivity and inert basal plane limit MoS₂'s practical application.
• Strain engineering and defect creation are strategies to enhance MoS₂ performance.

Purpose of the Study:

• To enhance the hydrogen evolution reaction (HER) activity of molybdenum disulfide (MoS₂) monolayers.
• To investigate the synergistic effects of biaxial strain and sulfur vacancies on MoS₂ HER performance.
• To develop a novel method for engineering 2D electrocatalysts.

Main Methods:

• Fabrication of patterned gold nanopillar arrays (AuNAs).
• Draping CVD-grown MoS₂ monolayers over AuNAs to induce biaxial strain.
• Oxygen plasma treatment to introduce sulfur vacancies.
• Electrocatalytic activity testing using on-chip microcell devices.

Main Results:

• Biaxial strain was successfully induced in MoS₂ monolayers by draping over AuNAs.
• Optimal strain and sulfur vacancy concentration (S_0.5μmV₅₀-MoS₂) significantly enhanced HER activity.
• Achieved an overpotential of 53 mV in 0.5 M H₂SO₄ for the optimized catalyst.
• Demonstrated synergistic enhancement from strain-induced active sites and vacancy defects.

Conclusions:

• Strain engineering and sulfur vacancy creation synergistically boost MoS₂ HER performance.
• This approach offers a promising route for developing advanced 2D electrocatalysts.
• The engineered MoS₂ shows potential for efficient hydrogen production.