Selenium-Enriched Nickel Selenide Nanosheets as a Robust Electrocatalyst for Hydrogen Generation

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Growing demand for clean and sustainable energy necessitates advancements in hydrogen production technologies.
• Earth-abundant, noble-metal-free catalysts are crucial for efficient hydrogen evolution reaction (HER).
• Pyrite-type transition-metal dichalcogenides are being investigated as potential HER catalysts.

Purpose of the Study:

• To synthesize and investigate Se-enriched NiSe2 nanosheet arrays as HER electrocatalysts.
• To explore the relationship between anion sites and HER activity in NiSe2.
• To understand the theoretical and experimental factors contributing to enhanced hydrogen evolution.

Main Methods:

• Synthesis of Se-enriched NiSe2 nanosheet array electrodes.
• Theoretical calculations to determine atomic hydrogen adsorption free energy on Ni and Se sites.
• Electrochemical measurements to evaluate HER performance, including overpotential and Tafel slope.

Main Results:

• Significantly lower free energy for atomic hydrogen adsorption on Se sites (0.13 eV) compared to Ni sites (0.87 eV).
• Electrode demonstrated excellent HER kinetics: low overpotential (117 mV at 10 mA cm⁻²) and Tafel slope (32 mV dec⁻¹).
• High stability and efficient conversion of H⁺ to H₂ attributed to excess selenium on the NiSe2 surface.

Conclusions:

• Se-enriched NiSe2 nanosheet arrays are highly effective noble-metal-free HER electrocatalysts.
• The anion (selenium) sites play a critical role in enhancing hydrogen evolution activity.
• This study provides insights into designing advanced catalysts for sustainable hydrogen production.