Enhancing the electrocatalytic activity of 2H-WS₂ for hydrogen evolution via defect engineering

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Transition metal dichalcogenides (TMDs) like WS2 are explored as non-noble metal catalysts for the hydrogen evolution reaction (HER).
• Current TMD catalysts suffer from limited active sites and poor electrical conductivity, hindering their efficiency.
• Exposing edge sites and engineering defects are key strategies to improve TMD catalytic performance.

Purpose of the Study:

• To develop a scalable method for enhancing the electrocatalytic activity of tungsten disulfide (WS2) for the HER.
• To investigate the role of defect engineering, specifically sulfur vacancies and metallic tungsten nanoparticles, in tuning WS2 catalytic sites.
• To understand the structure-activity relationship for modified WS2 electrocatalysts through experimental and theoretical evaluation.

Main Methods:

• Growth of vertically aligned 2H-WS2 on various substrates.
• Scalable defect engineering via thermal hydrogen treatment to create sulfur vacancies and W nanoparticles.
• Tuning of desulfurization extent by controlling H2 annealing conditions.
• Experimental characterization and theoretical calculations to evaluate HER activity.

Main Results:

• Vertically aligned WS2 structures were successfully grown, exposing edge sites.
• Thermal hydrogen treatment created tunable sulfur vacancies and metallic W nanoparticles (W/WS2-x).
• HER activity of W/WS2-x electrocatalysts was found to be controllable by annealing conditions.
• Experimental and theoretical analyses provided insights into the enhanced HER mechanism.

Conclusions:

• Defect engineering via controlled desulfurization is an effective strategy to enhance the HER activity of WS2.
• The W/WS2-x electrocatalysts show promising potential as efficient alternatives to noble metal catalysts for HER.
• Understanding the impact of defects is crucial for designing next-generation TMD-based electrocatalysts.