Electrocatalytic oxygen evolution over supported small amorphous Ni-Fe nanoparticles in alkaline electrolyte

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• The oxygen evolution reaction (OER) is vital for renewable energy technologies like water splitting and CO2 reduction.
• Sluggish OER kinetics and reliance on precious metals hinder widespread application.
• Developing efficient, low-cost electrocatalysts is essential for advancing these technologies.

Purpose of the Study:

• To synthesize and characterize inexpensive, amorphous nickel-iron oxide nanoparticles (NiFeOx/C) as OER electrocatalysts.
• To evaluate the activity, durability, and efficiency of these novel catalysts in alkaline media.
• To explore their potential application in (photo)electrochemical energy conversion devices.

Main Methods:

• Solution-phase nanocapsule synthesis of 4 nm Ni-Fe nanoparticles supported on carbon (NiFeOx/C).
• Electrochemical characterization including overpotential, Tafel slope, and Faradaic efficiency measurements.
• Long-term stability testing using chronoamperometry and post-test analysis via transmission electron microscopy (TEM).

Main Results:

• The Ni0.69Fe0.31Ox/C catalyst exhibited superior OER activity (280 mV overpotential at 10 mA cm⁻²) compared to NiOx/C and commercial Ir/C.
• A low Tafel slope of 30 mV dec⁻¹ and high Faradaic efficiency (97%) indicated efficient catalysis with minimal side reactions.
• The catalyst demonstrated excellent stability over 6 hours of operation without significant activity loss or particle aggregation.

Conclusions:

• Inexpensive, amorphous NiFeOx/C nanoparticles are highly active and durable electrocatalysts for the oxygen evolution reaction.
• The optimized Fe content (31%) in Ni-Fe nanoparticles maximizes catalytic performance.
• These findings present a promising pathway for efficient and cost-effective electrochemical energy conversion and storage systems.