Decoupling Electrolytic Water Splitting by an Oxygen-Mediating Process

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Decoupled water electrolysis offers flexible, high-purity hydrogen production using membrane-free electrolyzers.
• Effective mediator electrodes with suitable redox potential, capacity, and stability are critical for practical applications.

Purpose of the Study:

• To introduce a novel concept of oxygen-mediating redox mediators (ORMs) for decoupled water electrolysis.
• To investigate the performance of Bismuth oxide (Bi2O3) as an ORM material.

Main Methods:

• Fabrication and electrochemical characterization of Bi2O3 electrodes.
• Testing of the Bi2O3 electrode in a decoupled alkaline water electrolysis system.
• Integration with a Bi2O3-Zn battery for combined energy conversion and storage.

Main Results:

• The Bi2O3 electrode exhibited a reversible specific capacity of 300.8 mA h g-1.
• Outstanding cycling stability was achieved for over 1000 cycles at 2.0 A g-1.
• Successful demonstration of power-to-fuel (hydrogen) and chemical-to-power (battery) conversion.

Conclusions:

• Oxygen-mediating redox mediators offer a competitive route for membrane-free decoupled water splitting.
• Bi2O3 is a promising material for ORMs, enabling efficient hydrogen production and energy storage.
• The developed system provides a versatile platform for combined energy transformation and storage applications.