Optimized hierarchical nickel sulfide as a highly active bifunctional catalyst for overall water splitting

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Energy

Background:

• Non-noble metal electrocatalysts are crucial for sustainable water splitting.
• Achieving bifunctional catalysts for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) remains a challenge.

Purpose of the Study:

• To design and develop highly efficient bifunctional electrocatalysts based on Ni3S2 for overall water electrolysis.
• To optimize the catalytic activity for both HER and OER using a hierarchical Ni3S2 structure and Fe doping.

Main Methods:

• Hierarchical Ni3S2 structure engineering on Ni foam (NF) for HER optimization.
• Fe species introduction onto Ni3S2/NF via a simple dipping/drying method to enhance OER activity.
• Electrochemical characterization including overpotential measurements and durability testing.

Main Results:

• The c-Ni3S2/NF electrode showed a low overpotential of 220 mV for HER at 100 mA cm-2.
• The Fe-doped Fe-c-Ni3S2/NF catalyst demonstrated excellent OER activity with an overpotential of 193 mV at 10 mA cm-2.
• The assembled water electrolyzer exhibited a low cell voltage of 1.50 V at 10 mA cm-2 and 120 h durability.

Conclusions:

• The developed Fe-doped Ni3S2 material is a highly active and stable bifunctional electrocatalyst for overall water electrolysis.
• Remaining sulfur anions play a role in enhancing intrinsic OER activity.
• This strategy offers a promising route for low-cost, high-performance electrocatalyst design.