Anchored nanocatalysts enable efficient oxygen reduction in barium cobaltite cathodes

Area of Science:

• Materials Science
• Electrochemistry
• Energy Conversion

Background:

• Solid oxide fuel cells (SOFCs) face challenges with sluggish oxygen reduction reaction (ORR) kinetics at the cathode.
• Ex-solution, a method to generate nanoparticles from perovskite lattices, is a potential solution but underutilized in SOFC cathodes.

Purpose of the Study:

• To investigate the application of ex-solution to BaCo0.8Ta0.2O3-δ (BCT) cathodes doped with Ag, Cu, and Ni.
• To improve the ORR kinetics and overall performance of SOFC cathodes.

Main Methods:

• Doping BCT perovskite with Ag, Cu, and Ni.
• Controlled reducing conditions to induce ex-solution and form socketed nanoparticles.
• Structural and microscopic analyses (e.g., SEM, TEM) to characterize nanoparticle formation.
• Electrochemical impedance spectroscopy (EIS) to measure polarization resistance (Rp).
• Single-cell testing to evaluate power density.

Main Results:

• Confirmed the formation of socketed nanoparticles on the BCT perovskite surface after doping and ex-solution.
• Ex-solved cathodes showed significantly reduced Rp compared to non-ex-solved ones.
• Ex-solved BCT-Ag (eBCT-Ag) achieved the lowest Rp (0.0210 Ω cm² at 650 °C), a 49% reduction.
• A single-cell test using eBCT-Ag reached a maximum power density of ~0.68 W cm⁻² at 650 °C.

Conclusions:

• Successfully applied the ex-solution strategy to SOFC cathodes.
• Ex-solution effectively enhances cathode performance by reducing polarization resistance.
• The eBCT-Ag cathode demonstrates a promising pathway for designing high-performance SOFCs.