Engineering Atomic-Step Architectures in 2D WSe₂ through Kinetic Modulation for Efficient Hydrogen Evolution in PEM...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Platinum-based catalysts dominate hydrogen evolution reaction (HER) in proton exchange membrane (PEM) electrolyzers, but their cost and scarcity necessitate alternatives.
• Tungsten-based transition metal dichalcogenides (TMDs), like WSe2, are promising non-precious catalysts but require performance enhancement.
• The catalytic activity of TMDs is primarily attributed to their edge sites.

Purpose of the Study:

• To enhance the catalytic efficiency of WSe2 for HER by engineering abundant atomic steps.
• To investigate the performance of engineered WSe2 in practical PEM electrolyzers.
• To elucidate the mechanism behind the enhanced activity using theoretical calculations.

Main Methods:

• A kinetically-driven selenization process was employed to precisely control the formation of atomic steps on WSe2.
• Electrochemical performance was evaluated using overpotential and Tafel slope measurements.
• Long-term stability was tested in a PEM electrolyzer setup.
• Density Functional Theory (DFT) calculations were used to analyze hydrogen adsorption energetics.

Main Results:

• Engineered stepped WSe2 achieved a low overpotential of 97 mV at 100 mA/cm2 with a Tafel slope of 38.69 mV/dec.
• The catalyst demonstrated excellent practicality in PEM electrolyzers, reaching 1000 mA/cm2 at 1.82 V and showing stable operation for 200 hours.
• DFT calculations indicated that atomic steps lead to near-thermoneutral hydrogen adsorption Gibbs free energy, explaining the superior activity.

Conclusions:

• Atomic-scale edge structure engineering, specifically creating atomic steps, significantly boosts WSe2's HER catalytic efficiency.
• The developed stepped WSe2 presents a viable, high-performance, non-precious alternative for PEM electrolyzer technologies.
• This approach offers a pathway for designing advanced electrocatalysts by controlling edge site morphology.