Soft-template derived Ni/Mo₂C hetero-sheet arrays for large current density hydrogen evolution reaction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Efficient electrocatalysts are crucial for energy conversion technologies.
• Structural design and electronic properties significantly impact catalyst performance.
• Nickel-molybdenum carbide (Ni/Mo2C) heterojunctions show promise for electrocatalysis.

Purpose of the Study:

• To synthesize a novel Ni/Mo2C heterojunction catalyst with enhanced electrocatalytic activity for the hydrogen evolution reaction (HER).
• To investigate the structural and electronic properties influencing the catalyst's performance.
• To evaluate the long-term stability and industrial applicability of the developed catalyst.

Main Methods:

• A facile soft-template approach using polyvinylpyrrolidone (PVP) to grow Ni/Mo2C heterojunction nanosheet arrays on nickel foam (NF).
• Density functional theory (DFT) calculations to understand the electronic structure and active sites.
• Electrochemical testing to assess HER performance, including overpotentials and current densities.
• Long-term stability tests under industrially relevant conditions.

Main Results:

• Successfully synthesized Ni/Mo2C heterojunction nanosheet arrays on NF (NS-Ni/Mo2C@NF).
• DFT calculations revealed abundant active sites with moderate hydrogen adsorption free energy (ΔGH* = 0.037 eV).
• Achieved low overpotentials of 151 mV and 271 mV for current densities of 100 mA/cm2 and 1000 mA/cm2, respectively.
• Demonstrated excellent stability, operating for 500 hours without activity decay at 500 mA/cm2.

Conclusions:

• The NS-Ni/Mo2C@NF catalyst exhibits superior HER performance due to its unique structure and heterojunctions.
• The catalyst shows significant potential for efficient and stable hydrogen production.
• This work provides a promising strategy for designing advanced electrocatalysts for water electrolysis.