Regulating Local Atomic Environment around Vacancies for Efficient Hydrogen Evolution

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Defect engineering is crucial for designing advanced electrocatalysts.
• Focus has been on vacancies, but the local atomic environment's role is understudied.
• Understanding vacancy structure-activity relationships is key for catalyst optimization.

Purpose of the Study:

• To investigate the impact of local atomic environments of vacancies in molybdenum disulfide (MoS2) on catalytic activity.
• To develop a facile method for manipulating vacancy structures in MoS2.
• To correlate specific vacancy structures with hydrogen evolution reaction (HER) performance.

Main Methods:

• Developed a synthetic approach to control Mo-to-S ratios and thus local atomic environments of vacancies in MoS2.
• Synthesized MoS2 samples with varying vacancy types (Mo-terminated, S-terminated, and defect-free).
• Evaluated the electrocatalytic performance of synthesized MoS2 for the hydrogen evolution reaction (HER).

Main Results:

• MoS2 with Mo-terminated vacancies demonstrated superior HER performance compared to S-terminated and defect-free MoS2.
• The enhanced performance is attributed to tunable orbital orientation and distribution around vacancies.
• Optimized local atomic environments facilitate favorable hydrogen adsorption, increasing intrinsic per-site activity.

Conclusions:

• The local atomic environment of vacancies significantly influences electrocatalytic activity in MoS2.
• Mo-terminated vacancies are more effective for HER catalysis than S-terminated ones.
• This work provides insights for rational defect engineering in transition metal dichalcogenides (TMDs) and other catalysts.