Engineering interfacial structures to accelerate hydrogen evolution efficiency of MoS₂ over a wide pH range.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing efficient electrocatalysts for water splitting is critical for renewable energy.
• Existing catalysts often have limitations in performance or stability across a wide pH range.
• Low-cost, high-performance electrocatalysts are urgently needed for practical applications.

Purpose of the Study:

• To fabricate a novel hierarchical flower-like CoS₂@MoS₂ core-shell nanostructured electrocatalyst.
• To evaluate the electrocatalyst's performance for hydrogen evolution reaction (HER) across the entire pH range (0-14).
• To investigate the interfacial effects on HER activity using density functional theory (DFT) calculations.

Main Methods:

• A two-step strategy was employed to synthesize CoS₂@MoS₂ core-shell nanostructures on carbon paper.
• Electrochemical performance for HER was tested in acidic, neutral, and alkaline solutions.
• Density functional theory (DFT) was used to analyze the electronic structure and reaction mechanisms at the CoS₂-MoS₂ interface.

Main Results:

• The optimized CoS₂@MoS₂/CP catalyst demonstrated excellent HER activity with low overpotentials: 69 mV (acidic), 145 mV (neutral), and 82 mV (alkaline) at 10 mA cm⁻².
• The catalyst exhibited superior stability for over 48 hours in various pH conditions.
• DFT calculations revealed that the strong interfacial interaction between CoS₂ and MoS₂ significantly lowers the energy barriers for hydrogen adsorption and water dissociation.

Conclusions:

• The hierarchical CoS₂@MoS₂ core-shell nanostructure is a highly efficient and stable electrocatalyst for HER across a wide pH range.
• Interface engineering plays a crucial role in enhancing the catalytic activity by optimizing adsorption energies and reaction pathways.
• This work provides a promising strategy for designing advanced electrocatalysts for efficient water splitting.