Built-In Electric Field in Freestanding Hydroxide/Sulfide Heterostructures for Industrially Relevant Oxygen Evolution

Area of Science:

• Materials Science
• Electrochemistry
• Green Energy

Background:

• Alkaline water electrolysis (AWE) is key for green hydrogen production.
• Current oxygen evolution reaction (OER) electrodes face challenges like layer shedding and ion dissolution.
• High current densities are required for industrial AWE.

Purpose of the Study:

• To develop a stable and highly active OER electrode for industrial AWE.
• To address limitations of existing OER electrode materials.
• To investigate the role of built-in electric fields in electrode performance.

Main Methods:

• Scalable corrosion-electrodeposition method to synthesize NiFe-LDH/Ni3S2 heterostructures on nickel mesh.
• Characterization of electrode performance under high current densities in alkaline media.
• Validation in an alkaline electrolyzer system.

Main Results:

• Achieved ultra-low OER overpotentials: 202 mV at 10 mA cm⁻² and 290 mV at 800 mA cm⁻².
• Demonstrated superior steady-state stability and resistance to reverse current.
• Electrolyzer validation showed 800 mA cm⁻² at 1.908 V with excellent stability.

Conclusions:

• The NiFe-LDH/Ni3S2 heterostructure offers a promising solution for efficient and durable OER electrodes in AWE.
• The built-in electric field plays a crucial role in enhancing performance and stability.
• This work provides a blueprint for designing advanced electrodes for industrial green hydrogen production.