Active site manipulation in MoS₂ cluster electrocatalysts by transition metal doping

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Non-platinum group metal catalysts are crucial for sustainable water electrolysis.
• Molybdenum disulfide (MoS2) shows promise as an acid-stable electrocatalyst for the hydrogen evolution reaction (HER).
• Transition metal doping is explored to enhance MoS2 catalytic activity.

Purpose of the Study:

• To investigate the effect of cobalt doping on MoS2 for HER catalysis.
• To compare the influence of cobalt versus nickel doping on MoS2 HER performance.
• To elucidate the atomic mechanisms behind doping effects using theoretical calculations.

Main Methods:

• Controlled synthesis of cobalt-doped MoS2 clusters (MoS2-Co) using cluster beam deposition.
• Electrocatalytic testing of MoS2-Co for the hydrogen evolution reaction (HER).
• Density functional theory (DFT) calculations to analyze doping effects on surface vacancies.

Main Results:

• Cobalt doping significantly reduces the HER activity of MoS2, contrasting with nickel doping (MoS2-Ni).
• DFT calculations reveal that cobalt dopants deactivate HER-active surface vacancies.
• Adatom dopant-vacancy combination kinetics are over three orders of magnitude faster in MoS2-Co than MoS2-Ni.

Conclusions:

• Transition metal dopants exert fundamentally different influences on MoS2 HER electrocatalysts.
• Cobalt doping is detrimental to MoS2 HER performance due to vacancy deactivation.
• Surface atomic defects play a critical role in determining the behavior of doped MoS2 electrocatalysts.