Heterostructure Ni₃S₄-MoS₂ with interfacial electron redistribution used for enhancing hydrogen evolution

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing effective and affordable electrocatalysts for the hydrogen evolution reaction (HER) is critical for large-scale alkaline water electrolysis.
• Molybdenum disulfide (MoS2), while effective in acidic media, exhibits a high overpotential in alkaline solutions, limiting its application.

Purpose of the Study:

• To synthesize and characterize a novel nanospherical heterostructure catalyst composed of Ni3S4 and MoS2.
• To investigate the enhanced HER performance of the Ni3S4-MoS2 heterostructure in alkaline media.

Main Methods:

• One-pot synthesis of Ni3S4-MoS2 nanospherical heterostructures.
• Characterization using X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM).
• Electrochemical evaluation of HER activity, including overpotential and Tafel slope measurements, and long-term stability tests.
• Density functional theory (DFT) calculations to understand the synergistic effects and reaction mechanisms.

Main Results:

• The Ni3S4-MoS2 heterostructure exhibited abundant heterojunctions with interfacial electron redistribution.
• The catalyst demonstrated a low overpotential of 116 mV at 10 mA cm-2 in alkaline solution.
• Achieved a Tafel slope of 81 mV dec-1 and maintained stability for over 20 hours.
• DFT simulations revealed synergistic effects between Ni3S4 and MoS2 that accelerate the rate-determining steps of HER.

Conclusions:

• The Ni3S4-MoS2 heterostructure significantly enhances HER activity in alkaline media.
• The synergistic effects at the heterojunction interface are crucial for improved catalytic performance.
• This study presents a promising strategy for designing cost-effective and high-performance electrocatalysts for HER.