Uniquely integrated Fe-doped Ni(OH)₂ nanosheets for highly efficient oxygen and hydrogen evolution reactions

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Efficient electrocatalysts are crucial for large-scale hydrogen production via water splitting.
• Developing bifunctional electrocatalysts for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) remains a significant challenge.

Purpose of the Study:

• To fabricate and characterize Fe-doped Ni(OH)2 nanosheets on Ni foam (FeNiOH/NF) as a high-performance electrocatalyst for water splitting.
• To investigate the effect of Fe-doping on the electronic structure and electrocatalytic activity of Ni(OH)2 for OER and HER.

Main Methods:

• Facile hydrothermal synthesis of Fe-doped Ni(OH)2 nanosheets directly grown on commercial Ni foam.
• Electrochemical characterization including overpotential, Tafel slope, and long-term stability tests in 1.0 M KOH.

Main Results:

• FeNiOH/NF exhibited excellent OER activity with low overpotentials (271 mV at 20 mA cm-2, 318 mV at 100 mA cm-2) and a Tafel slope of 72 mV dec-1.
• The catalyst demonstrated remarkable stability, with only a 23 mV overpotential increase over 20 hours at 500 mA cm-2.
• High HER activity and robust stability were also observed.
• Overall water splitting achieved 10 mA cm-2 at 1.67 V in a two-electrode alkaline electrolyzer using FeNiOH/NF as both anode and cathode.

Conclusions:

• Fe-doping significantly enhances the electrocatalytic activity and stability of Ni(OH)2 for both OER and HER.
• The hierarchical architecture and modified electronic structure contribute to the superior performance.
• This FeNiOH/NF catalyst offers a promising, scalable alternative to state-of-the-art IrO2 for efficient water splitting technology.