Porous Fe-Doped β-Ni(OH)₂ Nanopyramid Array Electrodes for Water Splitting

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Efficient electrocatalysts are crucial for overall water splitting to produce clean hydrogen fuel.
• Nickel hydroxide-based materials show promise but often require structural modification for enhanced activity and stability.
• Developing bifunctional electrodes for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is a key challenge.

Purpose of the Study:

• To develop a highly efficient and stable electrode for overall water splitting.
• To investigate the effect of iron doping on the electrocatalytic activity of β-nickel hydroxide nanopyramids.
• To provide a facile synthesis route for advanced electrode materials.

Main Methods:

• Fabrication of a porous Fe-doped β-nickel hydroxide nanopyramid array on nickel foam (U-Fe-β-Ni(OH)₂/NF) using a self-templated strategy and anion-exchange reaction.
• Electrochemical characterization including cyclic voltammetry, linear sweep voltammetry, and chronoamperometry to evaluate OER and HER performance.
• Extensive material characterization and electrochemical measurements to elucidate the promotion mechanisms.

Main Results:

• The U-Fe-β-Ni(OH)₂/NF electrode exhibited outstanding bifunctional electrocatalytic activity for OER and HER in an alkaline medium.
• The optimal electrode achieved a current density of 10 mA cm^-2 at low overpotentials of 218 mV for OER and 121 mV for HER.
• The electrode demonstrated excellent stability during continuous water splitting and the iron doping significantly enhanced activity compared to undoped β-Ni(OH)₂.

Conclusions:

• Fe-doped β-nickel hydroxide nanopyramid arrays on nickel foam represent a highly efficient and stable electrode material for overall water splitting.
• The unique porous nanostructure and Fe-doping synergistically enhance electrocatalytic performance for both OER and HER.
• This work presents a facile and scalable approach for developing cost-effective, high-performance hydroxide-based electrodes for hydrogen production.