Robust Direct Hydrocarbon Solid Oxide Fuel Cells with Exsolved Anode Nanocatalysts.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Conventional solid oxide fuel cells (SOFCs) using Nickel/Yttria-Stabilized Zirconia (Ni/YSZ) anodes face challenges like carbon deposition when using hydrocarbon fuels.
• Perovskite anodes with in situ exsolved nanocatalysts offer a promising alternative, enhancing catalytic activity and mitigating carbon issues.
• Cathode-supported SOFCs provide a stable platform for high-temperature processing, crucial for integrating advanced anode materials.

Purpose of the Study:

• To demonstrate, for the first time, the application of exsolution technology in cathode-supported SOFCs with perovskite anodes for direct hydrocarbon utilization.
• To evaluate the cell performance and long-term stability of these novel SOFCs using various hydrocarbon fuels.
• To investigate the catalytic behavior of exsolved nanocatalysts, particularly concerning methane oxidation.

Main Methods:

• Fabrication of cathode-supported SOFCs utilizing a Sr₂Ti_0.8Co_0.2FeO_6-δ perovskite anode.
• In situ exsolution of Co-Fe alloy nanocatalysts onto the perovskite anode surface via a reduction process.
• Performance testing using hydrogen, methane, methanol, and ethanol at 800 °C, including long-term stability assessments.

Main Results:

• The cathode-supported SOFCs achieved the highest cell performance reported to date for perovskite anodes using methane.
• Exsolution of Co-Fe alloy nanoparticles increased cell power output by approximately 40%, reaching peak power densities of 0.59 W cm^-2 with methane.
• Stable power generation exceeding 110 hours was demonstrated with methane, methanol, and ethanol, showcasing high methane fuel utilization through complete oxidation.

Conclusions:

• The integration of anode catalyst exsolution with dendritically channeled cathode supports leads to robust hydrocarbon SOFCs.
• The developed perovskite anodes exhibit superior performance and stability compared to conventional Ni-based anodes for direct hydrocarbon fuel utilization.
• This approach represents a significant advancement in SOFC technology for efficient and stable operation with various hydrocarbon fuels.