Coupled Surface-Bulk Engineering of Ceria-Based Cathodes Enables High-Temperature CO₂ Electrolysis

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Solid oxide electrolysis cells (SOECs) are crucial for high-temperature electrochemical CO2 conversion.
• Limitations in SOEC cathode performance stem from inadequate surface reactivity and bulk transport.
• Ceria-based materials are promising but require performance enhancements.

Purpose of the Study:

• To improve the surface reactivity and bulk transport of ceria-based SOEC cathodes.
• To investigate the effect of dual-metal (Cobalt and Iron) incorporation on cathode performance.
• To develop a cost-effective strategy for high-performance ceria cathodes.

Main Methods:

• Rational dual-metal (Co, Fe) incorporation into Gadolinium-doped ceria (GDC) cathodes.
• Fabrication and testing of single SOEC cells with modified cathodes.
• Electrochemical performance evaluation at 800 °C.
• Mechanistic studies using surface and bulk characterization techniques.

Main Results:

• Co0.05Fe0.05-GDC cathodes exhibited enriched surface Ce3+-oxygen vacancy motifs and enhanced bulk transport.
• A single cell achieved a current density of 1.88 A cm-2 (2.20 A cm-2 with a thinner electrolyte).
• Stable operation exceeding 580 hours was demonstrated.
• Fe promoted CO2 adsorption/activation; Co improved oxygen migration and narrowed the bandgap.

Conclusions:

• Coupled engineering of surface reactivity and bulk transport is effective for ceria-based cathodes.
• Dual-metal doping with Co and Fe offers a cost-effective route to high-performance SOECs.
• The developed cathode design overcomes key limitations in CO2 electrolysis.